The Periodic Table of the Elements

Introduction

The idea that there were ultimate, elemental constituents of matter developed independently in three different philosophical traditions. There were Greek elements, Indian and Buddhist Elements, and Chinese Elements. The system of Indian elements underwent the most development, beginning with three -- fire, water, and earth -- and ending with five -- fire, water, earth, air, and aether. This development may have actually been a response to influence from Greek philosophy in the Hellenistic Age, when the earth, air, fire, and water of Empedocles were expanded to five by Aristotle's addition of aether, , the air or fire of the heavens. All ended up as Indian elements. Greeks arrived in India with Alexander the Great and remained nearby in the Kingdom of Bactria, where they even converted to Buddhism. In the Buddhist version of the five elements, aether, Sanskrit , became the Void, Sanskrit , shûnyatâ, "Emptiness," or Chinese , in line with Buddhist metaphysics. When the Buddhist system was exported to East Asia, it rested up against the original five elements of the Chinese system -- earth, fire, water, wood, and metal. Although I have imagined a combination of Buddhist and Chinese elements in the "Fantasy Seven Element Theory," such a combination was never carried out in either Buddhist or Chinese philosophy.

With all of these traditional elements, however, the theories were based on evident physical qualities -- we could even say the four states of matter, solid, (earth), liquid, (water), gas, (air), and plasma, (fire) -- except, of course, for aether, which is not directly encountered. While this had an intuitive appeal, there was little future in it. Instead, the theory of the modern elements begins with the largely Mediaeval system of the seven metals -- gold, silver, copper, iron, tin, lead, and mercury. In the European tradition, where, unlike China, metal was not an element in its own right, the metals were going to be regarded as varieties of earth,
The Metals
AgSilverMoonMonday
HgMercuryMercuryWednesday
CuCopperVenusFriday
AuGoldSunSunday
FeIronMarsTuesday
SnTinJupiterThursday
PbLeadSaturnSaturday
although exactly how a metal is differentiated from earth could not, of course, be accounted for. Like the other theories of elements, the metals were put into an elaborate system of associations, particularly with the visible planets and the days of the week.

All these metals had been known since antiquity. Gold, silver, and copper had been worked since the beginning of Middle Eastern Civilization. Tin was added to copper to make bronze. It was learned that by adding some charcoal to iron, it could be made very hard -- i.e. steel. Roman plumbing used lead, after which, plumbum, it is named. Mercury, "quick silver," became particuarly intriguing to Mediaeval alchemists, whose interest otherwise was trying to convert other metals, or anything, into gold. "Alchemy" comes from Arabic , al-kîmîyah, "chemistry," itself from Greek, , itself from the Egyptian name for Egypt, or . This traces the evolution of the practice from the Greeks, who figured it was from Egypt, through the Arabs. The efforts of the alchemists, curiously, paid off with the discovery and manipulation of other elements, such as Sulfur, Arsenic, Antimony, Bismuth, and Phosphorus. At right, we see a detail of the dramatic depiction of Hennig Brand (c.1630-c.1692/1710) discoverying Phosophorus in 1669, in The Alchymist, In Search of the Philosopher’s Stone, 1771, by Joseph Wright of Derby (1734-1797) -- click on the image for a popup of the full painting. And it turned out that that the charcoal used with iron, almost pure Carbon, was itself an element. So Carbon, like Sulfur and the metals, had occurred naturally without being recognized for what it was.

The laboratory equipment of the alchemists led to modern chemistry; and in the 18th century it was finally determined that fire had never been elemental, but was no more than a chemical process -- as determined by Antoine-Laurent de Lavoisier (1743-1794), at left, who also established that Sulfur was indeed an element (1777). And, by Lavoisier again, water was broken down into new elements, gases, which he named hydrogen ("water making") and oxygen ("sharp making"). Air was a mixture of a number of gases. A new one, carbon dioxide, was identified, with its miraculous healing properties immediately recognized -- which is why carbonated drinks, invented by Joseph Priestley (1733-1804), were sold in drug stores, at the "soda fountain," for a very long time -- and the naturally carbonated waters of hot springs are still viewed as healing, or at least relaxing. This was harmless enough; but the later discovery of the miraculous healing properties of Radium -- discovered by Marie Curie and her husband in 1898 -- led to many unnecessary deaths.

The dam burst in the 19th century, as one new element after another was identified, now with often obscure or whimsical names. In 1869 Dmitri Mendeleev detected a pattern. There was a periodicity in the properties of the elements, i.e. they repeated themselves in a regular , períodos, i.e. a "way around" (originally used for the circuit of the Greek Stephanitic Games). Hence the idea of the "periodic table." Mendeleev made some predictions about new elements, their weights and properties; and he turned out to be right. He didn't have a clue, of course, why this was happening. Nor did anyone else for a long time.

The structure of the table, and the periodicity of the elements, is due to the features of quantacized angular momentum. How this worked was first appreciated by Niels Bohr. As it is, we can detect a simple numerical series in the structure of the columns, like a chemical version of Bode's Law:  2, 6, 10, 14. If we divide by 2, because electrons can be left-handed or right-handed, we get:  1, 3, 5, 7, a simple sequence of odd numbers. This happens because of the values of angular momentum quanta:  0, 1, 2, 3 (orbitals identified as S, P, D, & F, respectively), which range as "magnetic substates" -- i.e. quantacized orientations in space in a magnetic field -- from positive to negative substates, e.g. for 3 we get +3, +2, +1, 0, -1, -2, -3 = 7. The diagram at left is actually for an angular momentum (L) of 4, which we do not see for electrons (it would be G Orbitals, which occur for protons and neutrons). As the "shells" of electrons fill up, we end up achieving both electrically neutral and extremely stable configurations, which we find in the "magic numbers" characteristic of the inert gases.

There is thus a tremendous simplicity, elegance, and beauty to this. Just what a physicist likes to see. The way electrons work in their actual atoms, however, often involves irregularities that current physics is not always able to explain.

Having discovered this wealth of elements, they turn out not to be elemental after all. The atoms of each element consist of sub-atomic particles, with the number of protons determining the atomic number of the element. Although the atomic character of the chemical elements was recognized, for the right reasons, by John Dalton (1766-1844) at the beginning of the 19th century, the validity of this discovered was hotly disputed by many, since the individual atoms could not be observed. Ernst Mach most thoroughly made a fool of himself in this respect, but features of his extreme empiricism, discussed elsewhere at this site because of his promotion of Leibniz's theory of space, remain popular with many philosophers and scientists. Today, individual atoms of the heaviest, artificial elements, created in the lab, can be detected and studied.

A few atoms of every element up to 118 have now been observed, but the highest ones exist too briefly for much information to be gleaned about them -- so far. Physicists still hope for an "island of stablity," where more long lived atoms will be found. Originally it was thought that might occur around 114; but the actual 114 has disappointed -- although with a half-life of 30 seconds, that actually seems pretty long. But everyone had their hopes on minutes or longer. Now hopes rest on 120 or 122. Actual super-heavy stable elements are unlikely, but they do supply material for interesting science fiction.

Names of the Elements

The names of the elements derive from vasty differences sources. And the names of common elements, of course, differ from language to language -- something easily disambiguated by the internationally established symbols, although sometimes there are disputes or problems and a few symbols have gotten changed. Quite a few places have gotten elements named after them, often for obscure locations in Germany, Sweden, or Russia. The origins of such names are not always obvious, as Hassium (108 Hs) is named after the German State of Hesse. We also get the exceeding obscure Ruthenium (44 Ru), which is actually named with an archaic name for Russia itself, namely Ruthenia. Americans have no difficulty recognizing the origins of Berkelium (97 Bk) and Californium (98 Cf); but Livermorium (116 Lv), named after the Lawrence Livermore Laboratory (founded by Edward Teller amid intense political controversy), will probably not ring a bell for most. Recent place names, as in that case, usually reflect the existence of labs where elements have been discovered, particularly for the United States, Russia, and Germany. Curiously, Britain, where so much basic laboratory physics was done, including the discovery of the atomic nucleus by Rutherford, and where the Latin name of London, Londinium, already sounds like the name of an element, has contributed no place names to elements.

A good number of elements are now named after scientists. I've tried to put together a complete list:

These names are heavy with experimental physicists, particularly those associated with the actual discovery of new elements, like Marie Curie and Ernest Lawrence. We do get Albert Einstein and Niels Bohr of purely theoretical physicsts, but other theoreticians, like Schrödinger, Heisenberg, and Dirac, are missing. And Bohr, of course, although a theoretician, was the one who provided the physics to understand the structure of the table. Otherwise, experimentalists like J. J. Thomson, who discovered the electron (1896), or Robert A. Millikan, who determined its charge (1910), are missing. Dmitri Mendeleev, who recognized regularities in the chemical elements and first constructed a periodic table, could not be overlooked, and wasn't; but John Dalton, who realized that the chemical elements were atomic, also could not be overlooked, but was (and is). Otherwise, we get Nicolaus Copernicus, whose contributions, although epic, had nothing to do with chemistry, the elements, or even the kind of physics involved here. Equally tangential might be Alfred Nobel, whose status as a chemist is probably overshadowed by his establishment of the Nobel Prizes. New elements, of course, like new asteroids, are named by their discoverers. Individuals associated with particular labs are (usually) only named posthumously, while living discoverers use the place names of the labs for self-reference, or perhaps self-congratulation. Living scientists Glenn Seaborg and Yuri Oganessian, both involved in the discovery of new elements, have now had elements named after them, Oganessian most recently (2016).

Sources and Uses

It is not difficult to find periodic tables of the chemical elements. What is provided here, however, is a table with information drawn from different sources that may not always be found together (though there is the massive Handbook of Chemistry and Physics, edited by Robert C. Weast and Melvin J. Astle, of which I have the 62nd edition, 1981-1982, CRC Press, Inc. -- and now the 88th Edition, CRC Handbook of Chemistry and Physics, 2007-2008, Editor-in-Chief David R. Lide, Ph.D.). Thus, atomic isotopes, half-lives, and decay modes are largely taken from Subatomic Physics, by Hans Frauenfelder and Ernest M. Henley (Prentice-Hall, Inc. 1974). Cosmic abundance of elements is taken from the Realm of the Universe, by George O. Abell (Holt, Rinehart, and Winston, Inc. 1976 -- Abell's catalogue of galaxy clusters has now enshrined his name to the far reaches of the universe). Some minerological information comes from An Introduction to Minerology for Geologists, by W.J. Phillips and N. Phillips (John Wiley & Sons, 1980), and the Manual of Minerology by Cornelius S. Hurlbut, Jr. and Cornelis Klein (John Wiley & Sons, 1977). Such an attempt at a comprehensive picture of the elements in nuclear, chemical, and minerological forms I have also found in a couple of laminated, single-sheet periodic tables published for students, the "Chemical Periodic Table," edited by C. Bello (Papertech Marketing Group, Inc., 1988), and the "Table of Periodic Properties of the Elements," by the Sargent-Welsh Scientific Company (1980), from which some information here is derived -- now especially the neutral atomic radii. In some respects those single-sheet tables are more comprehensive than the following; and now I have been derived some new information from a laminated "Periodic Table of the Elements" from "Innovating Science" by the Aldon Corporation (2012).

In 2003 I updated some of the data here from Nature's Building Blocks, An A-Z Guide to the Elements by John Emsley [Oxford, 2001]. Emsley, unfortunately, doesn't exhaustively give things like isotopes and decay modes. I don't know why one would want to publish a book on the elements without such things. A nice new treatment of the elements, with a wealth of information, unfortunately often in a cryptic graphic form, is The Elements, A Visual Exploration of Every Known Atom in the Universe, by Theodore Gray (Black Dog & Leventhal Publishers, Inc., New York, 2009). This has been updated in 2012, but again with a kind of cryptic presentation of the data -- for instance with images for the crystal structure, without any explanation of what these are all about, or even their names. This page supplies these difficiences in a footnote, and without too much figuring Gray's images can be matched with the various space lattices. Gray's treatment is also missing things like isotopes and decay modes; and Gray, an enthusiastic for collecting examples of all the elements, doesn't mention things like the derivation of the names of the elements. As it happens, Wikipedia pages on the elements now usually have everything anyone would want to know about any elements, including isotopes, decay modes, names, history, compounds, etc. But I have also spotted some errors.

Many of the sources above may seem somewhat out of date, but they reflect the period when I was studying these matters, and when I was especially intrigued to supplement a chemical view of the elements with a picture of the variety of nuclear isotopes. Although I have done some updating, this table is not intended, therefore, as a resource for chemistry, physics, or minerology students. It is a resource for philosophy of science, illustrating basic ideas and information, where the most up to date data and the provision of all chemically useful information may not be not necessary:  Data for reflection and theory, not for application and experiment. However, it is hard not to return here occasionally and to update some things, often with information from Wikipedia and elsewhere, where the purposes are more thorough and exhaustive than I have any interest in doing. Compared to some popular treatments, like Gray's The Elements, I think this page comes off favorably. The most recent updates and discussions were actually occasioned by buying "The Periodic Table of the Elements" shower curtain ("SMART by Simple Memory Art"), which has been featured on The Big Bang Theory television show for years.

Index and Explanation

Where to put Hydrogen and Helium in the Periodic Table is a nice question. In the following diagram they are in Groups 1 and 2, despite not being Alkali Metals or Alkaline Earths. However, they do belong with the s-block, where the S Orbitals are filling up. Hydrogen is generally put in Group 1, perhaps for that reason. In the main tables below, however, Hydrogen is put with the Halogens and Helium with the Inert Gases, which is where it is generally placed, since it really is an inert gas, for the same reason as the others. And Hydrogen is rather more like the Halogens than like the Alkali Metals. But Hydrogen is really sui generis and might sensibly be placed entirely on its own.

Elements marked radioactive, , have no stable isotopes and will decay into other elements. No element heavier than Bismuth (Bi 83) has a stable isotope. Some of these occur in Nature, such as Uranium (92 U), and some have only been made in the laboratory, such as Nobelium (102 No). Others occur in Nature but only because they are decay products of longer lived elements. They have short enough half-lives that they would have disappeared if not continually renewed by such decays. Thus, they exist in small enough quantities that they were not identified until radiation was discovered. So, Radium 226 (226Ra) has a half-life of 1600 years and was only discovered by Marie Curie in 1898. Nevertheless, these elements can be trouble. Radon, whose longest lived isotope, 222Rn, a decay product of Radium, only has a half-life of 3.8 days, can accumulate dangerously in people's basements, if those are sunk into rocks emitting the gas. Polonium, also discovered by Curie, and rather longer lived, was apparently used by the Russians to assassinate a political dissident in London. To the other recent aggressions of Putin's Russia, radiological warfare thus must be added.

Some elements are marked poisonous, . I have tried to restrict these to the ones that are chemically poisonous, even as most radioactive elements will cause radiation poisoning. Even though some radioactive elements are only mildly radioactive and are relatively harmless, the number of elements that could be responsible for radiation poisoning is now so large that it seems reasonable to avoid all the duplication with the icons. Just assume that radioactive elements are dangerous. On the other hand, some of the chemically poisonous elements are acutely poisonous, like Thallium, while others, like Lead, are only poisonous as the result of chronic ingestion. Thus, if Lead is used carefully, casual contact is not dangerous. The same does not quite hold for Mercury, which is not acutely poisonous but is more dangerous than Lead because its vapor can be breathed and because, as a liquid, Mercury can enter the body through cuts in the skin. The neurological damage resulting from Mercury exposure is what made the "Mad Hatter" mad, since Mercury was used and absorbed in the traditional making of hats. When I was a child, no one worried much about playing around a bit with Lead or Mercury. Now people flee in panic. Another dangerous category are the elements, like the Alkalis and Halogens, that are so chemically reactive that they cause burns and damage on immediate contact. This is also a kind of poison, but of an overt and more obvious character, like the danger of fire and acids. I have labelled some Halogens but no Alkalis poisonous, mainly because Chlorine was used as a poison gas in World War I. By the same reasoning, Polonium should be marked poisonous, since Vladimir Putin's Russia assassinated a dissident in London by poisoning him with Polonium, which killed him by radiation poisoning.

The atomic weight is the number of grams in one "mole" of the material, which here means the number of atoms given by Avogadro's Number, 6.022140857(74) x 1023. Carbon 12 is the isotope taken as the benchmark, so that the atomic weight of C 12 is exactly 12. More nuanced definitions treat of "Avogadro's Constant." Atomic weight is an average of all the naturally occurring isotopes, and there is also the factor that energy has mass, with nuclei up to Iron (Fe 26) having less energy(/mass) than the independent particles and nuclei above Iron having more energy(/mass). This is why the fusion of Hydrogen atoms releases energy, but the fission of Uranium atoms also releases energy. Atomic weights in parentheses are the average of the most stable isotopes for elements that either do not occur naturally or that are too short lived to have easily been detected in Nature. Other periodic tables only give integer mass numbers in such cases, although they are then sometimes misidentified as atomic weights.
Alkali Metals
Alkaline Earths (Metals)
MetalsRare Earths
(Metals)
Metalloids/
Semi-Metals
Observed
but
Unnamed
Non-
Metals
Halogens
Inert/
Noble Gases

Periodic tables typically color-code parts of the table to group chemically similar elements together. There is some variation in this. "Metals" is really the largest category, which here combines the Transition Metals of the d-block with other metals of the p-block. Sometimes these are distinguished. However, all the Alkalis and the Rare Earths are also metals. And the Non-Metals also really include the Halogens and Inert Gases. Since the Alkaline Earths and Rare Earths are actually Metals, the terminology has come to reflect this. The Metalloids or Semi-Metals are sometimes not distinguished from the Non-Metals, and Polonium (named for Marie Curie's native Poland) may or may not be identified as a Metal. The Lanthanide and Actinide Series of Rare Earths, the whole f-block, are sometimes distinguished, although it is not clear why this needs to be done. All but one of the Lanthanides occur naturally, and they have now become economically important, especially for powerful magnets. The Actinides, in turn, are all radioactive and are mostly artificial. Uranium and Plutonium have ominous uses that speak for themselves. The Inert Gases are "Noble" for not forming compounds with other elements -- the electron shells have filled up and are stable. Purple is used here for its Imperial associations. The most reactive elements, are those an electron short, the Halogens, or an electron beyond, the Alkalis, the Inert Gases.

1 Period
Group
234567 67
H 1
1, IA
Alkali
Metals
Li 3Na 11K 19Rb 37Cs 55Fr
87
s-block;
S Orbitals;
L=0
He 2
2, IIA
Alkaline Earths
Be 4Mg 12Ca 20Sr 38Ba 56Ra 88
 Rare Earths; f-block
Transition
Metals
;
d-block;
D Orbitals:
L=2
3, IIIBSc 21Y 39Lu 71Lr 103 La 57Ac 89
4, IVBTi 22Zr 40Hf 72Rf 104 Ce 58Th 90
5, VBV 23Nb 41Ta 73Db 105 Pr 59Pa 91
6, VIBCr 24Mo 42W 74Sg 106 Nd 60U 92
7, VIIBMn 25Tc 43Re 75Bh 107 Pm 61Np 93
VIIIB8Fe 26Ru 44Os 76Hs 108 Sm 62Pu 94
9Co 27Rh 45Ir 77Mt 109 Eu 63Am 95
10Ni 28Pd 46Pt 78Ds 110 Gd 64Cm 96
11, IBCu 29Ag 47Au 79Rg 111 Tb 65Bk 97
12, IIBZn 30Cd 48Hg 80Cn 112 Dy 66Cf 98
p-block;
P Orbitals;
L=1
13, IIIA
Boron
Family
B 5Al 13Ga 31In 49Tl 81Nh 113 Ho 67Es 99
14, IVA
Carbon Family
C 6Si 14Ge 32Sn 50Pb 82Fl 114 Er 68Fm 100
15, VA
Nitrogen Family
N 7P 15As 33Sb 51Bi 83Mc 115 Tm 69Md 101
16, VIA
Oxygen Family
O 8S 16Se 34Te 52Po 84Lv 116 Yb 70No 102
17, VIIA
Halogens
F 9Cl 17Br 35I
53
At 85Ts 117 Rare Earths;
f-block;
F Orbitals;
L=3
18, VIIIA
Inert
Gases
Ne 10Ar
18
Kr 36Xe 54Rn 86Og 118
1 Group
Period
234567 67

Scientific souces in physics and chemistry have begun avoid units like Angstroms, , 10-10m, and Fermis, 10-15m, in favor of nanometers, nm, 10-9m, and picometers, pm, 10-12m -- although the Fermi is actually equivalent to the femtometer, fm, 10-15m. This is being done because Angstroms are not are part of the "Basic" and official SI (Système International d'Unités) metric system. But this is not right. Measurement ought to be done in appropriate units, which means that milliliters (ml) really don't fit in the kitchen; and in fact the liter is now no more a part of the SI than is the Angstrom -- although every European country still dispenses gasoline and beer in liters (as does the United States, where a "quart" of alcohol is now a liter and a "fifth" [i.e. 4/5 of a quart] is 750ml). Where the metric paradigm has really broken up, however, is with computers, where binary and hexadecimal numbers have effectively sabotaged the whole decimal principle of the metric system. This is not going to go away any time soon. If a little common sense returns, ngstroms are perfectly convenient and appropriate units for the sizes of atoms and ions; and the difference in magnitude between the ngstrom and the Fermi nicely illustrates the difference in scale -- 105 = 100,000 -- between atoms and nuclei.

Hydrogen

Standard Entry:
Z=atomic number: symbol
Name of Element
gas at room temp =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
Z=0: n
neutron
{0}
n=c.10-5
[*]
B=1 1/2+
T=15.3m
(1932)
Z=1: H
Hydrogen
1.008g
-259.34/-252.88
{1}
{1S=1}
2.20/hcp
H=0.79
H+=c.10-5
[1x1012]
A=1 1/2+
99.985%
Deuterium
A=2 1+
0.015%
Tritium
B=3 1/2+
T=12.33y
(1766)
As an element, "neutronium," neutrons only exist free in neutron stars. Otherwise they decay into an electron (e-), a proton (p+) -- a Hydrogen atom -- and an anti-neutrino (). Although gravity is much, weaker than any of the forces within an atom, neutronium is created by the force of gravity collapsing the volume created by electrons in ordinary atoms. Since there are going to be many neutron stars in the universe, the number of free neutrons is liable to be considerable. Stars that are less massive form White Dwarves, where the atoms are not quite crushed; and stars that are more massive may collapse into Black Holes, where none of the other forces of nature can withstand gravity and neutrons themselves are collapsed down to a geometrical point. As a member of unstable atoms, neutrons can also decay, releasing an electron, as a beta particle, , and the anti-neutrino, , again. This adds a proton and increases the atomic number of the nucleus by one.

Hydrogen is the most abundant element in the universe. Its positive ion, H+, is simply a bare proton, whose size is no more than a Fermi, 10-15m (like the neutron), rather than the approximate size of most atoms, which is an Angstrom, , or 10-10m. But Hydrogen forms many non-ionic compounds, unlike either the Alkalis or Halogens with which it may be grouped. Instead, covalent bonds characterize important Hydrogen compounds, such as water, H2O, ammonia, NH3, or methane, CH4. These are among the most important compounds in the universe for the origin of life. Free Hydrogen molecules, H2, are not as reactive as Alkalis or Halogens, but they are easily flammable, as the Hindenberg learned to its loss (literally). In acids, such as hydrochloric acid, HCl, Hydrogen does have a strong ionic character. The opposite of acids, however, bases (or alkalines), also contain a hydrogen element, the OH- anion, as in sodium hydroxide, lye, NaOH -- my high school chemistry teacher, Mr. Falb, warned us that a piece of lye felt slippery, "because it is dissolving your skin." We add HCl to NaOH and we end up with water, H2O, and table salt, NaCl. Salt retains its ionic character, while water does not; although the acids and salts are in turn soluable in water, which reflects their ionic character. Hydrogen thus seems to play, not just on both teams, but on the neutral ground as well. Since there are weak acids (e.g. carbonic acid, H2CO3) and strong acids, there is actually a continuum between Hydrogen having an ionic or a covalent bond. This is measured by the pH test, which gives the concentration of effective H+ ions.

Alkali Metals

Standard Entry:
Z=atomic number: symbol
Name of Element
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
The Alkalis are characteristically highly reactive. Sodium cannot even be left in open air, or it will quickly oxidize; so it is sold protected by an inert gas, like Argon. If you toss sodium into water, it will break down the substance so quickly that the effect is explosive. So we expect to find these elements hidden in natural compounds, and they are. For all the explosive nature of Sodium and the poisonous nature of Chlorine, their compound, NaCl, ordinary table salt, is both delicious and nutritious (except, perhaps, for your blood pressure). A curious thing here is the rarity of Lithium, which is the least abundant of all the naturally occuring elements here. Lithium tends to be jumped over in the nucleogenesis in stars, which creates all the elements beyond Hydrogen. Otherwise, Sodium and Potassium figure in the mineral Feldspar (NaAlSi3O8, Plagioclase, and KAlSi3O8, Orthoclase), which is the most common mineral in the crust of both the Earth and the Moon (and other terrestrial planets). This is examined more throughly elsewhere. These minerals are in effect impurities of quartz, SiO2, where some Silicon is replaced by Aluminum, creating a negative ion, (AlSi3O8)-, just ready to welcome Na+ or K+.

Group 1, IA
3: Li
Lithium
6.941g
180.6/1342
{2 1} {1S=2}
{2S=1}
0.98/bcc
Li=2.05
Li+=0.68
[<3]
A=6, 1+
7.5%
A=7, 3/2-
92.5%
(1817)
11: Na
Sodium
22.989768g
97.8/883
{2 8 1}
{1S=2}
{2S=2+1P=6}
{3S=1}
0.93/bcc
Na=2.23
Na+=0.97
[1.9x106]
B=22
T=2.602y EC
A=23, 3/2+
100%
B=24
T=15.02h
(1807)
19: K
Potassium
39.0983g
63.71/759
{2 8 8 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6}
{4S=1}
0.82/bcc
K=2.77
K+=1.33
[120x103]
A=31, 1/2+
100%
B=40 /EC
T=1.28Gy
B=42
T=12.36h
(1807)
37: Rb
Rubidium
85.4678g
39.48/688
{2 8 18 8 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6}
{5S=1}
0.82/bcc
Rb=2.98
Rb+=1.47
[410]
A=85, 5/2-
72.17%
B=86
T=18.7d
A=87, 3/2-
27.83%
T=50Gy
(1861)
55: Cs
Cesium
132.90543g
28.39/671
{2 8 18 18
8 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=6}
{6S=1}
0.79/bcc
Cs=3.34
Cs+=1.67
[16]
A=133, 7/2+
100%
B=134
T=2.06y
B=135, 7/2+
T=2.8My
B=137
T=30.17y
(1860)
87: Fr
Francium
(233.0197)
27/677
{2 8 18 32
18 8 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=6}
{7S=1}
0.7/bcc
Fr+=1.80
B=212
T=19.3m EC
B=222
T=15m
A=223, 3/2+
T=22m
(1939)

Alkaline Earths

Standard Entry:
Z=atomic number: symbol
Name of Element
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
The Alkalis and Alkaline Earths get their names from Arabic. So "alkali" itself is directly from , al-qilî, "the base, alkali, lye." The root here, , qlw, or , qly, means "fry, bake, roast," so that the term appears to refer to alkaline ashes from burnt plants. Without the article, "base, alkali, lye" alternatively can be , qilw, , qily, or , qilan. The weak final consonant in the root, "w" or "y," is what generates this variety, since from inflected forms one cannot always tell what the root had been. The adjective, "alkaline, basic," is , qilwî. Examining this is a nice reminder of Mediaeval Islamic science, which has contributed enduring Arabic terminology in chemistry, astronomy, and mathematics.

The Alkaline Earths are, of course, metals, but like the Alkali Metals they oxidize quickly and do not occur naturally in metalic form. The most abundant elements here, Magnesium and Calcium, occur in key ways in both geology and biology. Calcium, like Sodium and Potassium above, is a defining element in Feldspars, specifically in the Plagioclase Series (CaAl2Si2O8). While the Calcium ion, Ca+2, seems significantly different in charge from Sodium, Na+, they share the Plagioclase Series because of the similar size of the ions. Otherwise, Calcium turns up in living things, particularly in bones and other kinds of skeletons. The key substance there is calcium carbonate, Calcite, CaCO3. This mostly constitutes limestone, which consists of the skeletons of invertebrates deposited in the sea, most conspicuously the Cretaceous seas that gave us both the White Cliffs of Dover and limestone formations in West Texas exposed by road cuts on Interstate 10 (geologists love road cuts, even if they are not as scenic as White Cliffs -- but West Texas is also a lot larger than Dover).

Magnesium is a slightly different story. This turns up in geology in the dark basaltic rocks of volanoes, particulary in the Olivine mineral Forsterite, Mg2SiO4, which we find in the lavas of Hawai'i. Geologically this is a very different province than where we find the Feldspars, with Sodium, Potassium, and Calcium, which are in light, continental rocks like granites. Magnesium shares its work with Iron (in Fayalaite, Fe2SiO4), which here looks like a kind of exogamy, as it has forsaken its Alkali fellows for a distant and very different metal. Why things work this was is an intriguing question, and the answer again would seem to be the size of the respective ions. The ion Mg+2, at 0.66 is smaller than the ions of Sodium, Potassium, or Calcium, but almost identical in size to Fe+3 at 0.64 -- and close to Fe+2 at 0.74 . I for one was enchanged to discover that much of the chemistry and crystallography of minerals depends on size rather than some other physical property.

Group 2, IIA
4: Be
Berylium
9.012182g
1289/2472
{2 2}
{1S=2}
{2S=2}
1.57/hcp
Be=1.40
Be+2=0.35
[12]
B=7
T=53.3d EC
A=9 3/2-
100%
B=10 0+
T=2.7My
(1798)
12: Mg
Magnesium
24.3050g
648.8/1089.8
{2 8 2}
{1S=2}
{2S=2+1P=6}
{3S=2}
1.31/hcp
Mg=1.72
Mg+2=0.66
[32x106]
A=24 0+
78.99%
A=25 5/2+
10%
A=26 0+
11.01%
B=28
T=20.9h
(1775)
20: Ca
Calcium
40.078g
842/1494
{2 8 8 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6}
{4S=2}
1.00/fcc
Ca=2.23
Ca+2=0.99
[2.5x106]
A=40 0+
96.94%
B=41 7/2-
T=80ky
A=42 0+
0.65%
A=43 7/2-
0.14%
A=44 0+
2.08%
B=45
T=165d
A=46 0+
0.003%
A=48 0+
0.19%
(1808)
38: Sr
Strontium
87.62g
769/1382
{2 8 18 8 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6}
{5S=2}
0.95/fcc
Sr=2.45
Sr+2=1.12
[760]
A=84 0+
0.56%
A=86 0+
9.9%
A=87 9/2+
7%
A=88 0+
82.6%
B=90 0+
T=28.9y
(1790)
56: Ba
Barium
137.327g
729/1805
{2 8 18 18
8 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=6}
{6S=2}
0.89/bcc
Ba=2.78
Ba+2=1.34
[130]
A=130 0+
0.1%
A=132 0+
0.095%
A=134 0+
2.4%
A=135 3/2+
6.5%
A=136 0+
7.8%
A=137 3/2+
11.2%
A=138 0+
71.9%
B=140
T=12.8d
(1808)
88: Ra
Radium
226.0254g
700/1536
{2 8 18 32
18 8 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=6}
{7S=2}
0.9/bcc
Ra+2=1.43
A=226 0+
T=1600y
B=228 0+
T=5.75y
(1898)

Transition Metals

Standard Entry:
Z=atomic number: symbol
Name of Element
liquid at room temp =
poisonous =
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
The transition metals consist of the famous and the ancient with the obscure and the modern. There are a lot of place names here. In just the first Group, Scandium is named after Scandia, the peninsula of Norway and Sweden from which all of Scandinavia derives its name; Yttrium, which people might wonder how to pronounce, is named after the town of Ytterby, Sweden, as is the Rare Earth Ytterbium (70 Yb); and Lutetium is from Lutetia, the Roman name for Paris. We've already seen that Ruthenium is named after Russia. Rhenium is named after the Rhine, Rhenus. On the other hand, Rhodium is named after the rose, , rhodôn in Greek. Tantalum is named after the character Tantalus, , from Greek mythology; and then Niobium is named after his daughter Niobe, . Both of them came to a bad end. Cadmium is named after , Cadmus, the legendary Phoenician founder of the city of Thebes, who also supposedly introduced the Phoenician alphabet to write Greek. Well somebody did. Molybdenum has acquired a name based on the Greek word for "lead," , mólybdos, because of some association with lead ores.

One of the more intriguing names with a Greek connection is that for Palladium. This is simply the Latin version of Greek , Palládion. The Palladium was a statue or fetish object of the goddess Athena, otherwise called , Pallas, upon which the safety of the City of Troy was supposed to depend. The Romans came to believe that the Palladium had been brought to Rome by Aeneas, who fled from Troy. This seems to mean that the Romans had something, apparently a small wooden statue of Athena, which they regarded as the original Palladium. But then we enter the realm of legend again. The story came to be told that the Emperor Constantine I took the Palladium to Constantinople, where it was buried under the porphyry pillar that was erected in the Forum of Constantine, upon which stood a statue of Constantine until it was thrown down by a storm on 5 April 1106 AD. The column, however, somewhat the worse for wear and called the "Burnt" pillar, still stands. No acknowledged effort appears to have been made to find anything under it. Meanwhile, Athena was also the patron goddess of the City of Athens, and apparently there was a Palladium associated with her there too, although we hear very little about it. That is not surprising, since such an object out to be kept secret and hidden.

GroupPeriod 4Period 5Period 6Period 7
3
IIIB
21: Sc
Scandium
44.9559g
1541/2831
{2 8 9 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=1}
{4S=2}
1.36/hcp
Sc=2.09
Sc+3=0.81
[1.1x103]
A=45 7/2-
100%
B=46
T=83.8d
(1879)
39: Y
Yttrium
88.9059g
1522/3338
{2 8 18 9 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=1}
{5S=2}
1.22/hcp
Y=2.27
Y+3=0.92
[210]
B=88
T=106.6d EC
A=89 1/2-
100%
(1794)
71: Lu
Lutetium
174.97g
1663/3395
{2 8 18 32 9 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=1}
{6S=2}
1.27/hcp
Lu=2.25
Lu+3=0.85
[7]
A=175 7/2+
97.4%
A=176 7-
2.6%
T=37Gy
(1907)
103: Lr
Lawrencium
(260.105)
(1627)/--
{2 8 18 32
32 8 3}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6}
{7S=2+7P=1}
B=256
T=35s
B=260
T=3m
(1961)
4
IVB
22: Ti
Titanium
47.90g
1670/3289
{2 8 10 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=2}
{4S=2}
1.54/hcp
Ti=2.00
Ti+3=0.76
Ti+4=0.68
[56x103]
A=46 0+
8%
A=47 5/2-
7.5%
A=48 0+
73.7%
A=49 7/2-
5.5%
A=50 0+
5.3%
(1791)
40: Zr
Zirconium
91.22g
1855/4409
{2 8 18 10 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=2}
{5S=2}
1.33/hcp
Zr=2.16
Zr+4=0.79
[600]
A=90 0+
51.4%
A=91 5/2+
11.2%
A=92 0+
17.1%
B=93 5/2+
T=950ky
A=94 0+
17.5%
B=95
T=64d
A=96 0+
2.8%
(1789)
72: Hf
Hafnium
178.49g
2231/4603
{2 8 18 32 10 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=2}
{6S=2}
1.3/hcp
Hf=2.16
Hf+4=0.78
[8]
A=174 0+
0.18%
T=2Py
A=176 0+
5.2%
A=177 7/2-
18.5%
A=178 0+
27.2%
A=179 9/2+
13.8%
A=180 0+
35.1%
B=182 0+
T=9My
(1923)
104: Rf
Rutherfordium
(261.11)
{2 8 18 32
32 10 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=2}
{7S=2}
B=257
T=4.5s
B=261
T=65s
(1964/1969)
5
VB
23: V
Vanadium
50.9414g
1910/3409
{2 8 11 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=3}
{4S=2}
1.63/bcc
V=1.92
V+2=0.88
V+3=0.74
V+4=0.63
V+5=0.59
[10x103]
A=50 6+
0.25%
T=40Py
A=51 7/2-
99.75%
(1830)
41: Nb
Niobium
92.9064g
2469/4744
{2 8 18 12 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=4}
{5S=1}
1.6/bcc
Nb=2.08
Nb+4=0.74
Nb+5=0.69
[200]
B=91 9/2+
T=LONG
B=92 7+
T=20My
A=93 9/2+
100%
B=94 6+
T=20ky
B=95
T=35.15d
(1801)
73: Ta
Tantalum
180.9479g
3020/5458
{2 8 18 32 11 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=3}
{6S=2}
1.5/bcc
Ta=2.09
Ta+5=0.68
[1]
A=180 8+
0.012%
A=181 7/2+
99.988%
B=182
T=115d
(1802)
105: Db
Dubnium
(262.114)
{2 8 18 32 32
11 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=3}
{7S=2}
B=262
T=40s
(1968)
6
VIB
24: Cr
Chromium
51.996g
1863/2672
{2 8 13 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=5}
{4S=1}
1.66/bcc
Cr=1.85
Cr+3=0.63
Cr+6=0.52
[690x103]
A=50 0+
4.35%
B=51
T=27.7d EC
A=52 0+
83.79%
A=53 3/2-
9.5%
A=54 0+
2.36%
(1797)
42: Mo
Molybdenum
95.94g
2623/4639
{2 8 18 13 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=5}
{5S=1}
2.16/bcc
Mo=2.01
Mo+4=0.70
Mo+6=0.62
[150]
A=92 0+
14.8%
B=93 5/2+
T=3ky
A=94 0+
9.1%
A=95 5/2+
15.9%
A=96 0+
16.7%
A=97 5/2+
9.5%
A=98 0+
24.4%
B=99
T=66.02h
A=100 0+
9.6%
(1778)
74: W
Tungsten
183.85g
3422/5730
{2 8 18 32 12 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=4}
{6S=2}
2.36/bcc
W=2.02
W+4=0.70
W+6=0.62
[300]
A=180 0+
0.13%
B=181
T=140d EC
A=182 0+
26.3%
A=183 1/2-
14.3%
A=184 0+
30.7%
B=185
T=75.1d
A=186 0+
28.6%
B=188
T=69d
(1783)
106: Sg
Seaborgium
(263.118)
{2 8 18 32
32 12 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=4}
{7S=2}
B=263
T=0.9s
B=266
T=21s
(1974)
7
VIIB
25: Mn
Manganese
54.9380g
1246/2062
{2 8 13 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=5}
{4S=2}
1.55/cub
Mn=1.79
Mn+2=0.80
Mn+3=0.66
Mn+4=0.60
Mn+7=0.46
[260x103]
A=53 7/2-
T=11My EC
A=54
T=313d EC
A=55 5/2-
100%
B=56
T=2.58h
(1774)
43: Tc
Technetium
98.9062g
2204/4265
{2 8 18 13 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=5}
{5S=2}
1.9/hcp
Tc=1.95
Tc+7=0.56
A=97 9/2+
T=2.6My EC
B=98 7 6+
T=1.5My
B=99 9/2+
T=210ky
(1937)
75: Re
Rhenium
186.2g
3186/5596
{2 8 18 32 13 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=5}
{6S=2}
1.9/hcp
Re=1.97
Re+4=0.72
Re+7=0.56
[2]
A=185 5/2+
37.5%
A=187 5/2+
62.5%
T=50Gy
(1925)
107: Bh
Bohrium
(262.12)
{2 8 18 32
32 13 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=5}
{7S=2}
B=267
T=17s
B=270
(1981)
VIII
B
8 26: Fe
Iron
55.847g
1538/2862
{2 8 14 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=6}
{4S=2}
1.83/bcc
Fe=1.72
Fe+2=0.74
Fe+3=0.64
[25x106]
A=54 0+
5.8%
A=56 0+
91.7%
A=57 1/2-
2.14%
A=58 0+
0.31%
B=59
T=44.6d
A=60 0+
T=100ky
(ancient)
44: Ru
Ruthenium
101.07g
2334/4150
{2 8 18 15 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=7}
{5S=1}
2.2/hcp
Ru=1.89
Ru+4=0.67
[66]
A=96 0+
5.5%
A=98 0+
1.9%
A=99 5/2+
12.7%
A=100 0+
12.6%
A=101 5/2+
17.1%
A=102 0+
31.6%
A=104 0+
18.6%
B=106
T=367d
(1844)
76: Os
Osmium
190.2g
3033/5012
{2 8 18 32 14 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=6}
{6S=2}
2.2/hcp
Os=1.92
Os+6=0.69
[6]
A=184 0+
0.02%
A=186 0+
1.6%
A=187 1/2-
1.6%
A=188 0+
13.3%
A=189 3/2-
16.1%
A=190 0+
26.4%
A=192 0+
41.0%
B=194
T=6y
(1804)
108: Hs
Hassium
{2 8 18 32
32 14 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=6}
{7S=2}
B=273
T=20s
B=277
(1984)
9 27: Co
Cobalt
58.9332g
1495/2928
{2 8 15 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=7}
{4S=2}
1.88/fcc
Co=1.67
Co+2=0.72
Co+3=0.63
[32x103]
B=56
T=78.8d EC
B=57
T=270d EC
B=58
T=71.3d EC
A=59 7/2-
100%
A=60
T=5.27y
(1735)
45: Rh
Rhodium
102.9055g
1963/3697
{2 8 18 16 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=8}
{5S=1}
2.28/fcc
Rh=1.83
Rh+3=0.68
[26]
B=101
T=3.3y EC
A=103 1/2-
100%
(1803)
77: Ir
Iridium
192.2g
2447/4428
{2 8 18 32 15 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=7}
{6S=2}
2.20/fcc
Ir=1.87
Ir+4=0.68
[160]
A=191 3/2+
37.4%
B=192
T=74.2d EC
A=193 3/2+
62.6%
(1804)
109: Mt
Meitnerium
{2 8 18 32
32 15 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=7}
{7S=2}
B=276
B=268
T=0.07s
(1982)
10 28: Ni
Nickel
58.71g
1455/2914
{2 8 16 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=8}
{4S=2}
1.91/fcc
Ni=1.62
Ni+2=0.69
[2.1x106]
B=57
T=36h EC
A=58 0+
68%
B=59 3/2-
T=80ky EC
A=60 0+
26.1%
A=61 3/2-
1.1%
A=62 0+
3.6%
B=63
T=92y
A=64 0+
0.9%
(1751)
46: Pd
Palladium
106.4g
1555/2964
{2 8 18 18}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
2.20/fcc
Pd=1.79
Pd+2=0.80
Pd+4=0.65
[20]
A=102 0+
1%
B=103
T=17d EC
A=104 0+
11%
A=105 5/2+
22.2%
A=106 0+
27.3%
B=107 5/2+
T=6.5My
A=108 0+
26.7%
A=110 0+
11.8%
(1803)
78: Pt
Platinum
195.09g
1769.0/3827
{2 8 18 32 16 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=8}
{6S=2}
2.28/fcc
Pt=1.83
Pt+2=0.80
Pt+4=0.65
[100]
A=190 0+
0.013%
T=700Gy
A=192 0+
0.78%
A=194 0+
32.9%
A=195 1/2-
33.8%
A=196 0+
25.3%
A=198 0+
7.2%
(16 cent.)
110: Ds
Darmstadtium
{2 8 18 32
32 17 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=9}
{7S=1}
B=281
T=1.6m
(1984)
11
IB
29: Cu
Copper
63.546g
1085/2563
{2 8 18 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=1}
1.90/fcc
Cu=1.57
Cu+=0.96
Cu+2=0.72
[11x103]
A=63 3/2-
69.1%
B=64 / EC
T=12.7h
A=65 3/2-
30.9%
B=67
T=61.88h
(ancient)
47: Ag
Silver
107.868g
961.93/2163
{2 8 18 18 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=1}
1.93/fcc
Ag=1.75
Ag+=1.26
Ag+2=0.89
[7]
A=107 1/2-
51.83%
B=108
T=127y EC
A=109 1/2-
48.17%
B=110
T=252d
B=111
T=7.45d
(ancient)
79: Au
Gold
196.9665g
1064.43/2857
{2 8 18 32 18 1}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=1}
2.54/fcc
Au=1.79
Au+=1.37
Au+3=0.85
[5]
B=195
T=183d EC
B=196
T=6.18d EC
A=197 3/2+
100%
B=198
T=2.696d
B=199
T=3.15d
(ancient)
111: Rg
Roentgenium
{2 8 18 32
32 17 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=9}
{7S=2}
B=280
B=272
T=1.5ms
(1994)
12
IIB
30: Zn
Zinc
63.37g
419.58/907
{2 8 18 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2}
1.65/hcp
Zn=1.53
Zn+2=0.74
[28x103]
A=64 0+
48.9%
B=65
T=244.1d EC
A=66 0+
27.8%
A=67 5/2-
4.1%
A=68 0+
18.6%
A=70 0+
0.62%
(16th cent)
48: Cd
Cadmium
112.40g
321.108/767
{2 8 18 18 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2}
1.69/hcp
Cd=1.71
Cd+2=0.97
[72]
A=106 0+
1.2%
A=108 0+
0.9%
B=109
T=453d EC
A=110 0+
12.4%
A=111 1/2+
12.8%
A=112 0+
24.0%
A=113 1/2+
12.3%
A=114 0+
28.8%
A=116 0+
7.6%
(1817)
80: Hg
Mercury
200.59g
-38.836/356.66
{2 8 18 32 18 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2}
2.00/rhm
Hg=1.76
Hg+2=1.10
[<100]
A=196 0+
0.15%
A=198 0+
10.1%
A=199 1/2-
16.9%
A=200 0+
23.1%
A=201 3/2-
13.2%
A=202 0+
29.7%
B=203
T=46.8d
A=204 0+
6.8%
(ancient)
112: Cn
Copernicium
{2 8 18 32
32 18 2}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=10}
{7S=2}
B=285
T=0.28ms
(1996)

Boron Family

Standard Entry:
Z=atomic number: symbol
Name of Element
poisonous =
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
Boron is the name of a small town in California, apparently named after the mining and hauling of borax (hydrated sodium borate, Na2B4O7*10H2O) from Death Valley, something that actually didn't last long but, like the Old West itself, is romanticized as "Death Valley Days" [1952-1970] -- a show hosted by Ronald Reagan [1964–1965]. The name "Boron" is itself actually derived from "borax" (trying to make it analogous to "Carbon"), which is derived from Arabic , bauraq, "borax." In Arabic, this is treated like a foreign word, and it is said to be derived from Persian. This is one of the many substances known to the Greeks and Arabs from the evaporite deposits in North Africa and other desert climates. Thus, borax was found in Death Valley because it is a desert basin where minerals wash in, do not wash out, and then are concentrated in dry lakes. A similar phenomenon is seen in the sand of White Sands, New Mexico, which is all gypsum, a hydrous calcium sulphate, CaSO4*2H2O.

The only really abundant element here is Aluminum -- the British version is indeed Aluminium -- which is, geologically and mineralogically, one of the most important elements of all. Because of its presence in Feldspars, the most common mineral in the crust of the Earth, Aluminum is one of the most abundant elements on earth; but recovering the Aluminum was never an easy matter, and bauxite ores (named after Baux, France) of weathered Aluminium oxides, which are not just everywhere, eventually made its production economical. Before then, Aluminum was extremely valuable; and the little pyramid of Aluminum on the top of the Washington Monument was a precious wonder of the age. Now, Aluminum fills the skies as the bodies of aircraft and fills the kitchen with Aluminum foil -- previously Tin foil. The name "Aluminium" comes from alum, an astringent variety of sulfates of Aluminum, from Latin alumen (genitive aluminis) but also cognate, oddly, to English "ale." This also has a cognate in Greek, , alýdoimos, which is glossed is the equivalent of , pikrós, "pointed, sharp, pungent, bitter." The semantic range of "bitter" can easily encompass alum and kinds of beer or ale.

Group 13, IIIA
5: B
Boron
10.81g
2092/4002
{2 3}
{1S=2}
{2S=2
+2P=1}
2.04/tet
B=1.17
B+=0.23
[<160]
A=10 3+
19.8%
A=11 3/2-
80.2%
(1808)
13: Al
Aluminum
26.981
660.452/2520
{2 8 3}
{1S=2}
{2S=2+1P=6}
{3S=2+3P=1}
1.61/fcc
Al=1.82
Al+3=0.51
[3.3x106]
B=26 5+ /EC
T=740ky
A=27 5/2+
100%
(1827)
31: Ga
Gallium
69.72g
29.7741/2205
{2 8 18 3}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=1}
1.81/orh
Ga=1.81
Ga+2=0.62
[630]
A=67
T=78.2h EC
A=69 3/2-
60.2%
A=71 3/2-
40%
B=72
T=14.1h
(1875)
49: In
Indium
114.82g
156.634/2073
{2 8 18 18 3}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=1} 1.78/tet
In=2.00
In+3=0.81
[40]
A=113 9/2+
4.3%
B=114
T=49.51d IT
A=115 9/2+
95.7%
T=500Ty
(1863)
81: Tl
Thallium
204.37g
304/1473
{2 8 18 32
18 3}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=1}
2.04/hcp
Tl=2.08
Tl+=1.47
Tl+3=0.95
[8]
A=203 1/2+
29.5%
B=204
T=3.77y
A=205 1/2+
70.5%
(1861)
113: Nh
Nihonium
{2 8 18 32
32 18 3}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=10}
{7S=2+7P=1}
B=284
(2004)
named after

Carbon Family

Standard Entry:
Z=atomic number: symbol
Name of Element
poisonous =
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
The name of Carbon looks like the Greek word , kárbon, "coal," "black"; but this may actually have been borrowed from Latin carbo, "burning" or "burnt wood," i.e. charcoal, as in the carbonarius, the "charcoal burner," someone who makes charcoal. Thus, a company like Kingsford, which supplied charcoal to the modern barbecuer, is a carbonarius. The Greek word turns up in a striking historical instance, as the epithet of the Empress Zoë Carbonopsina, the fourth wife of the Emperor Leo VI the Wise (886-912) and the mother of the Emperor Constantine VII Porphyrogenitus (913-959). Leo outlived three wives, none of whom produced a male heir. Unlike Henry VIII, he didn't divorce or execute any of them; but, unlike Henry VIII, the Church had objected to his third marriage and absolutely prohibited a fourth one, regarding it as the equivalent of prostitution. Usually, Churches make provisions for political necessity, but the Greek Church, and the Patriarch of Constantinople, were made of sterner stuff. So Leo fathered a son on his mistress, Zoë. The Patriarch agreed to baptize the son if Zoë were excluded from the Palace. So Constantine, known as "Porphyrogenitus," "Born in the Purple," which, as a bastard, he wasn't, was baptized and legitimized. Leo then found a pliable priest to marry him to Zoë. The Patriarch was furious, but, after all, a marriage is a marriage. So Leo got Zoë as well as an heir. And Zoë apparently was beautiful, called , Karbônopsína, "Coal Black Eyes." She then served as Regent for her son until 919.

Life on Earth consists of carbon based compounds -- proteins, amino acids, etc. Carbon works its way into living things by way of carbon dioxide, CO2, which is ultimately added by volcanoes to the atmosphere. Plants then metabolize the CO2, through photosynthesis or chemosynthesis, producing nutrients and Oxygen that are the basis of all other life. Plants and animals then deposit Carbon in the crust of the Earth by way of fossils, coal, oil, and the calcium carbonate of limestone, CaCO3. This means that all life on Earth is essentially a precipitate of carbon dioxide. Nevertheless, Environmental Protection Agency (EPA) of the United State, an agency without Constitutional basis, has declared that carbon dioxide is a "pollutant," because it is thought to contribute to Global Warming. The Courts have let this stand because the Courts have generally allowed irresponsible and unaccountable administrative agencies to do whatever they want. What is behind this is an ideology that regards human life as evil, as itself the "pollutant," and wants to depopulate the Earth as much as posssible, leaving most remaining humans (except the ideological elite, like Al Gore and Leonardo DiCaprio) living in conditions of Ice Age poverty -- something already achieved, except for the mass death part, in Cuba, their ideal of government -- although the mass death part has been tried, as in Cambodia, which was idolized until the Vietnamese, for their own purposes, showed the literal mountains of skeletons to the world. Many people, of course, are deceived about these goals and may even believe that "de-development" will leave them as well off as they are. Or they agree with the goals and simply don't understand their significance and consequences.

Science fiction likes the idea that Silicon could as well be a basis of life as Carbon. They both can form four covalent bonds. However, while CO2 is a gas at temperatures on the surface of the Earth, silicon dioxide, SiO2, is a mineral and a rock:  Quartz. This is unpromising. Perhaps Silicon would behave like Carbon at much higher temperatures, but then this greatly restricts the environments in which that could happen. Indeed, as lava, Silicon commonly rises to the surface of the Earth from just such high temperature conditions; and even on the surface the lavas may have temperatures of 2000 degrees Celsius. But no Silicon based life forms come up with the lava -- although, again, that would make for good science fiction stories. Instead, Silicon based minerals constitute most of the crust of the Earth, as I have considered elsewhere. Peridotite, the rock that appears to rise from the Mantle of the Earth and retain its composition, seems to evolve into all other other silicate rocks, but it shows no evidence of life.

Tin and Lead have been known since Antiquity, but they actually seem to be surprisingly rare as elements. Lead, which the Romans used as a sweetener and fashioned into plumbing, and which recently was used to strengthen paints, has now become a source of fear and panic because of the possibility of poisoning, both acute and chronic. Indeed, the possible insanity of Roman Emperors like Caligula, and the seeming sterility of Roman elites, may have been the result of lead poisoning; and the white, lead-based makeup of early modern stage actors, as in Shakespeare's day, seems to have destroyed their skin and led to deaths that were premature even by the standards of the time. Nevertheless, the amount of lead slowly grows, since it is often the final decay product of heavier, unstable elements.

Group 14, IVA
6: C
Carbon
12.011g
3826/3827
{2 4}
{1S=2}
{2S=2
+2P=2}
2.55/hex
C=0.91
C+4=0.16
[420x106]
B=11
T=20.4m
A=12 0+
98.892%
A=13 1/2-
1.108%
B=14 0+
T=5692y
(ancient)
14: Si
Silicon
28.0855g
1414/3267
{2 8 4}
{1S=2}
{2S=2+1P=6}
{3S=2+3P=2}
1.90/fcc
Si-4=1.98
Si=1.46
Si+4=0.39
[40x106]
A=28 0+
92.2%
A=29 1/2+
4.7%
A=30 0+
3.1%
(1823)
32: Ge
Germanium
72.59g
938.3/2834
{2 8 18 4}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=2}
2.01/fcc
Ge=1.52
Ge+2=0.73
Ge+4=0.53
[3.2x103]
B=68
T=275d EC
A=70 0+
20.7%
A=72 0+
27.5%
A=73 9/2+
7.7%
A=74 0+
36.4%
A=76 0+
7.7%
(1886)
50: Sn
Tin
118.69g
231.9681/2603
{2 8 18 18 4}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=2} 1.96/fcc
Sn-4=2.15
Sn=1.72
Sn+2=0.93
Sn+4=0.71
[25]
A=112 0+
1.0%
A=114 0+
0.66%
A=115 1/2+
0.35%
A=116 0+
14.4%
A=117 1/2+
7.6%
A=118 0+
24.1%
A=119 1/2+
8.6%
A=120 0+
32.8%
B=121
T=76y
A=122 0+
4.7%
A=124 0+
5.8%
B=126 0+
T=100ky
(ancient)
82: Pb
Lead
207.2g
327.502/1750
{2 8 18 32
18 4}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=2}
2.33/fcc
Pb=1.81
Pb+2=1.20
Pb+4=0.84
[71]
B=202 0+
T=300ky EC
A=204 0+
1.4%
T=140Py
B=205 5/2-
T=14My EC
A=206 0+
24.1%
A=207 1/2-
22.1%
A=208 0+
52.4%
A=210 0+
22.3%
T=22.3y
(ancient)
114: Fl
Flerovium
{2 8 18 32
32 18 4} {1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=10}
{7S=2+7P=2}
B=289
T=30.4s
(1998)

Nitrogen Family

Standard Entry:
Z=atomic number: symbol
Name of Element
gas at room temp =
poisonous =
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
With Nitrogen, we seem to have an explanation for why the Greeks associated chemistry with Egypt, to the point of using the name of Egypt, . Thus, the name that has been given to the element, "Nitrogen," means "niter making." Niter, from Latin nitrum and Greek , nítron, is natron, from Spanish natrón and Arabic , nat.rûn. Extraordinary, the Greek and/or the Arabic words appear to come from Egyptian , "divine" (the adjective from , "god"). Natron, which is a Sodium or Potassium Nitrate, NO3- or Nitrite, NO2-2, seems to have been called "divine" in Egyptian because it was used to mummify bodies, which prepares them for the afterlife. Such a substance could only be obtained from environments in which evaporites develop in closed basins of generally arid places. Thus, we find borax in Death Valley and natron in Egypt. Where the Egyptians could obtain a lot of their natron, northwest of Cairo, is still called the Wadi Natrun, .

Even more intriguing is the derivation of the name of one of the most important basic compounds of Nitrogen, ammonia, NH3. This is from sal ammoniac, Latin sal ammoniacus, the "ammoniac" salt. This was something else obtained from Egypt, apparently from the Siwa Oasis, northwest of Cairo again, where there was an Oracle of the god Amon, , that was visited by Alexander the Great while in Egypt. Thus, Latin ammoniacus is from Greek , ammoniakos, an adjective of , the god Amon. Evaporite substances were not obtainable in Greece, where even getting salt from evaporating sea water will not concentrate minerals in the same way that they accumulate over millennia in desert basins and their dry lakes. With no one having much of an idea of what chemistry or even alchemy would eventually involve, Egypt as the source of various evaporite substances was enough to lend its name to the use or study of such things.

But there's more. Compounds of both Arsenic and Antimony have been known since Antiquity and were identified in purified state by alchemists. Like natron and ammonia, Antinomy carries us back to the Egyptians. The Egyptians, with no sun glasses, used a black eye shadow, an Antimony compound, as protection against sunlight (much as football players do today). This is best known by its Arabic name, , kuh.l, or "kohl"; but it was known to the Egyptians as or, with several other variants, . The interesting determinatives here include three grains of sand, to indicate powdered preparations, or a single grain of sand with a plural sign, to the same effect. Losing the initial "m," as some variants have it in Egyptian, the same word turns up in Greek as , stímmi or, addapted to Greek morphology, , stímmis (and other variations), meaning the same thing. This is close enough to the Egyptian that it certainly gives us the original central vowel, and of course the "t" is missing because, as in Hebrew and Arabic, this is a feminine ending not normally pronounced in full. The Greek word turns up in Latin as stibium, from which the Sb symbol of Antinomy derives; but the next step is a little mysterious, since Latin antimonium looks like it retains the -tim- center of the Greek word, but with additions. I have not seen these explained.

While Antimony adds to our roster of substances and names from Egypt, Arsenic is a different story. The Latin arsenicum and Greek , arsenikón, clearly give the modern word and the chemical symbol, As, for Arsenic. Greek is said to have borrowed the word from Syriac, but then Syriac is supposed to have gotten it from Persian, and it has Indo-European cognates (including "yellow" in English). The word quoted in Persian, however, may be given as , zarnikh, in the Arabic alphabet. But Persian was not written in the Arabic alphabet until after the era when Greek would probably have have been borrowing from Syriac, and the identical word occurs this way in Arabic itself. Treated as a foreign word, the Arabic word would have been borrowed from Persian, but not from the New Persian written in the Arabic alphabet, but from Middle Persian, or Pahlavi, for which the Internet probably doesn't have either a font (from Aramaic) or many experts in the language. From Pahlavi, the trail to Syriac and Greek, as well as independently to Arabic, is reasonable.

Group 15, VA
7: N
Nitrogen
14.0067g
-210.0042/
-195.80
{2 5}
{1S=2}
{2S=2+2P=3}
3.04/hex
N=0.75
N+3=0.16
N+5=0.13
[87x106]
A=14 1+
99.64%
A=15 1/2-
0.36%
(1772)
15: P
Phosphorus
30.9738g
44.14/277
{2 8 5}
{1S=2}
{2S=2+1P=6}
{3S=2+3P=3}
2.19/cub
P=1.23
P+3=0.44
P+5=0.35
[390x103]
A=31 1/2+
100%
B=32
T=14.26d
(1669)
33: As
Arsenic
74.9216g
603/603
{2 8 18 5}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=3}
2.18/rhm
As=1.33
As+3=0.58
As+5=0.46
[260]
B=73
T=80.3d EC
B=74
T=17.9d EC
A=75 3/2-
100%
(c.1250)
51: Sb
Antimony
121.75g
630.755/1587
{2 8 18 18 5}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=3} 2.05/rhm
Sb=1.53
Sb+3=0.76
Sb+5=0.62
[8]
A=121 5/2+
57.3%
A=123 7/2+
42.7%
B=124
T=60.2d
B=125
T=2.7y
(1540)
83: Bi
Bismuth
208.9806g
271.422/1564
{2 8 18 32
18 5}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=3}
2.02/rhm
Bi=1.63
Bi+3=0.96
Bi+5=0.74
[<80]
B=207
T=38y EC
B=208 5+
T=368ky EC
A=209 9/2-
100%
T=1.9x1019y
B=210
T=3My/5d
(c.1450)

Oxygen Family

Standard Entry:
Z=atomic number: symbol
Name of Element
gas at room temp =
poisonous =
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
Once upon a time, living things on Earth began generating a deadly gas, which slowly filled the atmosphere, poisoning and killing the very living things that had made it. While some might see this story as about human beings releasing carbon dioxide, CO2, and causing global warming, it is not true that carbon dioxide poisons or kills anything, while the substance just described, molecular Oxygen, O2, when released in the depths of geological time, did in fact poison and kill most of life on Earth. The remnants of ancient life survive as anaerobic bacteria. Meanwhile, other life evolved that actually metabolized Oxygen, which enabled it to become much more active and complex than anerobic bacteria ever could. Of course, carbon dioxide is itself metabolized by plants, which means that, far from being a poison, it is essential to life on Earth. Indeed, the Carbon in carbon dioxide, as I have noted here, provides the chemical basis of all life on Earth. Nevertheless, Oxygen remains dangerous. Fires happen because Oxygen is available. As George Washington said of government, fire is a dangerous servant and a terrible master; and the damage and loss of life can be considerable when it gets out of control.

Like Oxygen, both Sulfur and Selenium are both essential and dangerous to life. Sulfur tends to fall into the category of chemically dangerous without being the sort of thing that is deliberately or accidentally ingested. Instead, Sulfur can occur pure in nature, at the vents of volcanoes. This is what the Bible called "brimstone," and no one thought that it was a very good thing -- God rains it down on Sodom and Gomorrah. At the same time, the pure Sulfur is liable to occur with hydrogen sulfide, H2S, which is the smell of rotten eggs. Both Sulfur and Selenium occur in organic substances; but concentrations of Selenium becomes poisonous. The southern part of the San Juaquin Valley in California is actually a basin, and the waters of the Kern River, especially when drawn off for agriculture, dry up without draining to the ocean. As in desert dry lakes, this concentrates minerals from the river, which includes toxic levels of Selenium. Otherwise, it is hard to know what about this element warrants its name, which is from the Greek word for "Moon," , Selénê. It is thus the counterpart of Helium, which is named after the Sun, , Hélios. Selenium then seems to have no more connection to Helium that it does to Selene, the vampire character played by Kate Beckinsale in the Underworld movies [2003, 2006, 2012].

Group 16, VIA
8: O
Oxygen
15.9994g
-218.789/
-182.97
{2 6}
{1S=2}
{2S=2
+2P=4}
3.44/mon
O-2=1.40
O=0.65
O+6=0.10
[690x106]
A=16 0+
99.756%
A=17 5/2+
0.039%
A=18 0+
0.205%
(1774)
16: S
Sulfur
32.06g
115.22/444.60
{2 8 6}
{1S=2}
{2S=2+1P=6}
{3S=2+3P=4}
2.58/orh
S-2=1.74
S=1.09
S+4=0.37
S+6=0.30
[16x106]
A=32 0+
95.0%
A=33 3/2+
0.75%
A=34 0+
4.2%
B=35
T=87.2d
A=36 0+
0.015%
(ancient)
34: Se
Selenium
78.96g
221/685
{2 8 18 6}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=4}
2.55/hex
Se-2=1.93
Se=1.22
Se+4=0.50
Se+6=0.42
[2.7x103]
A=74 0+
0.9%
B=75
T=118.5d
A=76 0+
9.0%
A=77 1/2-
7.5%
A=78 0+
23.5%
B=79 7/2+
T=65ky
A=80 0+
50%
A=82 0+
9.0%
(1817)
52: Te
Tellurium
127.60g
449.57/988
{2 8 18 18 6}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=4} 2.1/hcp
Te-2=2.11
Te=1.42
Te+4=0.70
Te+6=0.56
[260]
A=120 0+
0.09%
B=121
T=154d IT
A=122 0+
2.4%
A=123 1/2+
0.87%
T=12Ty IT
A=124 0+
4.6%
A=125 1/2+
7.0%
A=126 0+
18.7%
B=127
T=109d IT
A=128 0+
31.8%
A=130 0+
34.5%
(1782)
84: Po
Polonium
(208.9824)
254/962
{2 8 18 32
18 6}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=4}
2.0/cub
Po=1.53
Po+6=0.67
B=208
T=2.9y
B=209 1/2-
T=102y
B=210
138.38d
(1898)
116: Lv
Livermorium
{2 8 18 32
32 18 6}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10
+5F=14}
{6S=2+6P=6
+6D=10}
{7S=2+7P=4}
A=293
T=61ms
(2000)

Halogens

Standard Entry:
Z=atomic number: symbol
Name of Element
gas at room temp =
liquid at room temp =
poisonous =
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
The Halogens only need one electron to achieve the stablity of the Inert Gases. They thus easily produce negative ions, and their match made in heaven is thus witht the alkali metals, which easily shed an electron and become positive ions. So Chlorine jumps for joy to be matched with Sodium, which produces sodium chloride, NaCl -- table salt. Indeed, Halogens and Alkalis make salts, whose characteristic is an ionic bond that leaves the constituent atoms relatively free and easily water soluable. There are few contrasts in nature as dramatic as the contrast between indepenent Chlorine and Sodium and their combined salt. It is one of things that would have bewildered the Ancients, just like the discovery that water, far from being elemental, is itself a compound to two hitherto unknown gases, Oxygen and Hydrogen.

Speaking of Hydrogen, which has already been treated here separately. Like the Alkalis, Hydrogen will lose an electron to become a positive ion, H+. This makes it seem out of place with the Halogens, but then gaining an electron is all it needs to become the electrical equivalent of Helium. But it is fairly casual about doing either. We must go all the way down to Astatine to find a Halogen whose electronegativity is as low as Hydrogen, but it is still far higher than the Alkalis. It is just not as reactive as any of the common Halogens or Alkalis. So Hydrogen can have a strongly ionic character in an acid like hydrochloric acid, HCl, but then be the very definition of acidic neutrality in water, H2O.

Fluorine and Chlorine are reactive enough to be chemically dangerous. The most disturbing evidence of this was the use of Chlorine as a poison gas in World War I. Breathing it severely damages the lungs. Many soldiers died horribly from it. On the other hand, we get down to Iodine, and it is something that used to be found in every medicine cabinet as a antiseptic.

Group 17, VIIA
1: H
Hydrogen
1.008g
-259.34/ -252.88
{1}
{1S=1}
2.20/hcp
H=0.79
H+=c.10-5
[1x1012]
A=1 1/2+
99.985%
Deuterium
A=2 1+
0.015%
Tritium
B=3 1/2+
T=12.33y
(1766)
9: F
Fluorine
18.9984g
-219.67/ -188.20
{2 7}
{1S=2}
{2S=2+2P=5}
3.98/mon
F-=1.33
F=0.57
F+7=0.08
[36x103]
B=18
T=109.8m
A=19 1/2+
100%
(1771)
17: Cl
Chlorine
35.453g
-100.97/-34.05
{2 8 7}
{1S=2}
{2S=2+1P=6}
{3S=2+3P=5}
3.16/tet
Cl-=1.81
Cl=0.97
Cl+5=0.34
Cl+7=0.27
[220x103]
A=35 3/2+
75.77%
B=36 2+
T=300ky
A=37 3/2+
24.23%
B=38
T=37.2m
(1774)
35: Br
Bromine
79.904g
-7.25/59.10
{2 8 18 7}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=5}
2.96/orh
Br-=1.96
Br=1.12
Br+5=0.47
Br+7=0.39
[540]
A=79 3/2-
50.69%
A=81 3/2-
49.31%
B=82
T=35.3h
(1826)
53: I
Iodine
126.9045g
113.6/185.25
{2 8 18 18 7}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=5} 2.66/orh
I-=2.20
I=1.32
I+5=0.62
I+7=0.50
[44]
A=127 5/2+
100%
B=129 7/2+
T=16My
B=131
T=8.04d
(1811)
85: At
Astatine
(209.9871)
302/337
{2 8 18 32
18 7}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=5}
2.2/--
At=1.43
At+7=0.62
B=209
T=5.4h EC
B=210 5+
T=8.1h EC
B=211
T=7.21h EC
(1940)

Inert Gases

Standard Entry:
Z=atomic number: symbol
Name of Element
gas at room temp =
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
When Dmitri Mendeleev proposed the principle of the periodic table in 1869, only one inert gas had been discovered. That was Helium. But this discovery was recent enough (1868) that Mendeleev might not have known about it yet; and the formulation of his theory, over the years, certainly could not have considered its significance. Part of its significance for us is that the discovery of Helium teaches an important lesson in the history of philosophy and the philosophy of science. The founder of Positivism, Auguste Comte (1798-1857), had said that we would never know what the Sun was made of. This is right up there with the statement of David Hume, "Our senses inform us of the colour, weight, and consistence of bread; but neither sense nor reason can ever inform us of those qualities which fit it for the nourishment and support of a human body" [Enquiry Concerning Human Understanding, Oxford, 1902, 1972, p.33]. Hume would be confounded by most of modern chemistry, let alone the organic chemistry that describes nutrients. What Comte could not anticipate was that the elements, when excited, emit characteristic spectra of light. Coming from the Sun, there was the spectrum of an element that had not otherwise been observed in the lab. So it was named after the Sun, which is , Hêlios in Greek -- Helium in the neuter gender in Latin. So Comte was refuted by an element actually discovered on the Sun, sort of adding insult to injury. The problem with both Comte and Hume was their Empiricism, which could not allow imagination, abstract mathematics, and the invisible as part of proper science. We also see trouble from this with Ernst Mach (1838-1916), who kept denying the atomic theory of matter but is still widely regarded as an important philosopher of science. There is no telling why Edgar Rice Burroughs chose "Helium" as the name for his capital city of Mars (cf. A Princess of Mars, 1912).

What Mendeleev could not have known is that the inert gases would reveal and confirm the whole prinicple of the periodic table. They have the most conistently similar properties of any other Group on the table. And those properties principally follow from their inability to form compounds with other elements, or even molecules with each other (as with H2 or O2). All this is because the electron Orbitals have all filled up, leaving no dearth or excess of electrons to be attracted or lost. The stability of this is what makes the elements unreactive. They are thus just what is needed when something needs to be kept in a non-reactive atmosphere; and they all can be electrically stimulated, as in Neon signs, without anything happening to them. The inert gases are also called the "noble gases," because they are "above their company," as Jane Austin would say. So I have used purple for the background color here, to recall the statement of the Empress Theodora about the "purple."

Group 18, VIIIA
2: He
Helium
4.00260g
-272.38/ -268.93
{2}
{1S=2}
--/hcp
He=0.49
[80x109]
A=3 1/2+
10-4%
A=4 0+
100%
(1868)
10: Ne
Neon
20.179g
-248.59/ -246.05
{2 8}
{1S=2}
{2S=2+2P=6}
--/fcc
Ne=0.51
[37x106]
A=20 0+
90.5%
A=21 3/2+
0.27%
A=22 0+
9.2%
(1898)
18: Ar
Argon
39.948g
-189.35/-185.9
{2 8 8}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6}
--/fcc
Ar=0.88
[1.0x106]
A=36 0+
0.34%
B=37
T=35.02d EC
A=38 0+
0.07%
B=39
T=265y
A=40 0+
99.59%
(1894)
36: Kr
Krypton
83.80g
-157.4/-153
{2 8 18 8}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6}
--/fcc
Kr=1.03
[1.9x103]
A=78 0+
0.35%
A=80 0+
2.25%
B=81 7/2+
T=210ky EC
A=82 0+
11.6%
A=83 9/2+
11.5%
A=84 0+
57.0%
B=85
T=10.7y
A=86 0+
17.3%
(1898)
54: Xe
Xenon
131.30g
-111.8/-108.1
{2 8 18 18 8}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10}
{5S=2+5P=6}
--/fcc
Xe=1.24
[214]
A=124 0+
0.10%
A=126 0+
0.09%
A=128 0+
1.9%
A=129 1/2+
26.4%
A=130 0+
3.9%
A=131 3/2+
21.2%
A=132 0+
27%
B=133
T=5.25d
A=134 0+
10.5%
B=135
T=9.1h
A=136 0+
8.9%
(1898)
86: Rn
Radon
(222.0176)
-71/-62
{2 8 18 32
18 8}
{1S=2}
{2S=2+2P=6}
{3S=2+3P=6
+3D=10}
{4S=2+4P=6
+4D=10
+4F=14}
{5S=2+5P=6
+5D=10}
{6S=2+6P=6}
--/fcc
Rn=1.34

A=222 0+
T=3.824d
(1900)

Rare Earths

Standard Entry:
Z=atomic number: symbol
Name of Element
no stable isotopes; all radioactive =
atomic weight in grams/mole
melting/boiling point, oC
{electrons in shells}
electronegativity/crystal structure
Atoms & Ions=radius in Angstroms ()
[cosmic abundance/1012 Hydrogen atoms]
A/B=mass number of isotope, spin & parity
relative isotope abundance (%)
T=half life    decay mode
(date of discovery)
Period 6
Lanthanides
Period 7
Actinides
57: La
Lanthanum
138.9055g
918/3457
{2 8 18 18 9 2}
1.10/hex
La=2.74
La+3=1.14
[66]
B=137 7/2+
T=60ky EC
A=138 5-
0.09%
T=110Gy
A=139 7/2+
99.91%
B=140
T=40.3h
(1839)
89: Ac
Actinium
(227.0278)
1051/3200
{2 8 18 32 18 9 2}
1.1/fcc
Ac+3=1.18
A=227 3/2-
T=21.772y
(1899)
58: Ce
Cerium
140.12g
798/3426
{2 8 18 20 8 2}
1.12/fcc
Ce=2.70
Ce+3=1.07
Ce+4=0.94
[76]
A=136 0+
0.19%
A=138 0+
0.26%
A=140 0+
88.5%
A=142 0+
11.1%
T=50Py
B=144
T=284d
(1803)
90: Th
Thorium
232.0381g
1755/4788
{2 8 18 32 18 10 2}
1.3/fcc
Th=1.80
Th+4=1.02
[7]
B=228
T=1.913y
B=229 5/2+
T=7340y
B=230 0+
T=77ky
A=232 0+
100%
T=14.1Gy
(1828)
59: Pr
Praseodymium
140.0977g
931/3512
{2 8 18 21 8 2}
1.13/hex
Pr=2.67
Pr+3=1.06
Pr+4=0.92
[35]
A=141 5/2+
100%
B=142
T=19.1h
(1885)
91: Pa
Protactinium
231.0359g
1572/--
{2 8 18 32 20 9 2}
1.5/bct
Pr+3=1.13
Pr+4=0.98
Pr+5=0.89
A=231 3/2
T=32.5ky
(1917)
60: Nd
Neodymium
144.24g
1021/3068
{2 8 18 22 8 2}
1.14/hex
Nd=2.64
Nd+3=1.04
[71]
A=142 0+
27.1%
A=143 7/2-
12.2%
A=144 0+
23.9%
T=2.1Py
A=145 7/2-
8.3%
A=146 0+
17.2%
B=147
T=11.1d
A=148 0+
5.7%
A=150 0+
5.6%
(1885)
92: U
Uranium
238.0508g
1132.3/3818
{2 8 18 32 21 9 2}
1.38/bcc
U=1.38
U+4=0.97
U+6=0.80
[<4]
B=232 0+
T=72y
B=233 5/2+
T=159ky
A=234 0+
0.0055%
T=244ky
A=235 7/2-
0.72%
T=710My
B=236 0+
T=24My
A=238 0+
99.28%
T=4.49Gy
(1789)
61: Pm
Promethium
(144.9127)
1042/3512
{2 8 18 23 8 2}
1.13/dcp
Pm=2.62 B=145 5/2+
T=17.7y EC
B=147 7/2+
T=2.623y
(1947)
93: Np
Neptunium
(237.0482)
639/--
{2 8 18 32 22 9 2}
1.36/orh
Np+3=1.10
Np+4=0.95
Np+7=0.71
B=236 6-
T=5000y EC
B=237 5/2+
T=2.14My
B=239
T=2.346d
(1940)
62: Sm
Samarium
150.36g
1074/1791
{2 8 18 24 8 2}
1.17/rhm
Sm=2.59
Sm+3=1.00
[63]
A=144 0+
3.1%
B=146 0+
T=100My
A=147 7/2-
15.0%
T=110Gy
A=148 0+
11.2%
T=8Py
A=149 7/2-
13.8%
T=10Py
A=150 0+
7.4%
B=151
T=93y
A=152 0+
26.7%
A=154 0+
22.8%
(1879)
94: Pu
Plutonium
(244.0642)
640/3230
{2 8 18 32 24 8 2}
1.28/mcl
Pu+3=1.08
Pu+4=0.93
B=238 0+
T=87.75y
A=239 1/2+
T=24390y
B=240 0+
T=6540y
B=242 0+
T=387ky
B=244 0+
T=83My
(1940)
63: Eu
Europium
151.96g
822/1597
{2 8 18 25 8 2}
1.2/bcc
Eu=2.56
Eu+3=0.98
[5]
A=151 5/2+
47.8%
B=152
T=13y EC
A=153 5/2+
52.2%
B=154
T=8.5y
(1896)
95: Am
Americium
(243.0614)
1176/2607
{2 8 18 32 25 8 2}
1.3/hcp
Am+3=1.07
Am+4=0.92
B=241 5/2-
T=433y
B=243 5/2-
T=7370y
(1944)
64: Gd
Gadolinium
157.25g
1313/3266
{2 8 18 25 9 2}
1.20/hcp
Gd=2.54
Gd+3=0.97
[13]
B=150 0+
T=1.8My
A=152 0+
0.20%
T=110Ty
A=154 0+
2.2%
A=155 3/2-
14.9%
A=156 0+
20.6%
A=157 3/2-
15.7%
A=158 0+
24.7%
A=160 0+
21.7%
(1880)
96: Cm
Curium
(247.0703)
1345/--
{2 8 18 32 25 9 2}
1.3/dcp
B=242
T=163.2d
B=244
T=18.12y
B=245 7/2+
T=8700y
B=246 0+
T=4650y
B=247 9/2-
T=15.4My
B=248 0+
T=340ky SF
B=250 0+
T=11ky
(1944)
65: Tb
Terbium
158.9254g
1356/3223
{2 8 18 27 8 2}
1.2/hcp
Tb=2.51
Tb+3=0.93
Tb+4=0.81
[2]
B=158
T=1.2ky EC
A=159 3/2+
100%
B=160
T=72.3d
(1843)
97: Bk
Berkelium
(247.0703
1050/--
{2 8 18 32 27 8 2}
1.3/dcp
B=247 3/2-
T=1400y
B=248 8-
T=9y
(1949)
66: Dy
Dysprosium
162.50g
1412/2562
{2 8 18 28 8 2}
1.22/hcp
Dy=2.49
Dy+3=0.92
[13]
A=156 0+
0.06%
T=200Ty
A=158 0+
0.10%
A=160 0+
2.3%
A=161 5/2+
18.9%
A=162 0+
25.5%
A=163 5/2-
24.9%
A=164 0+
28.2%
(1886)
98: Cf
Californium
(242.0587)
900/--
{2 8 18 32 28 8 2}
1.3/--
B=249 9/2-
T=352y
B=251 1/2+
T=900y
(1950)
67: Ho
Holmium
164.9303g
1474/2695
{2 8 18 29 8 2}
1.23/hcp
Ho=2.47
Ho+3=0.91
[3]
A=165 7/2-
100%
B=166
T=1.2ky
(1879)
99: Es
Einsteinium
(252.083)
860/--
{2 8 18 32 29 8 2}
1.3/--
B=252
T472d
B=253
T=20.47d
B=254 7+
T=276d
(1952)
68: Er
Erbium
167.26g
1529/2863
{2 8 18 30 8 2}
1.24/hcp
Er=2.45
Er+3=0.89
[7]
A=162 0+
0.14%
A=164 0+
1.6%
A=166 0+
33.4%
A=167 7/2+
22.9%
A=168 0+
27.0%
A=170 0+
15.0%
(1843)
100: Fm
Fermium
(257.0951)
(1527)/--
{2 8 18 32 30 8 2}
1.3/--
B=253 1/2+
T=3.0d
B=255
T=20.1h
B=257 9/2+
T=82d
(1953)
69: Tm
Thulium
168.9342g
1545/1947
{2 8 18 31 8 2}
1.25/hcp
Tm=2.42
Tm+3=0.87
[4]
A=169 1/2+
100%
B=170
T=128.6d
B=171
T=1.92y
(1879)
101: Md
Mendelevium
(258.10)
(827)/--
{2 8 18 32 31 8 2}
1.3/--
B=256 0-
T=77m
B=258
T=55d
(1955)
70: Yb
Ytterbium
173.04g
819/1194
{2 8 18 32 8 2}
1.1/fcc
Yb=2.40
Yb+3=0.86
[6]
A=168 0+
0.14%
B=169
T=32d EC
A=170 0+
3.0%
A=171 1/2-
14.3%
A=172 0+
21.9%
A=173 5/2-
16.2%
A=174 0+
31.8%
B=175
T=4.19d
A=176 0+
12.7%
(1907)
102: No
Nobelium
(259.1009)
(827)/--
{2 8 18 32 32 8 2}
1.3/--
B=253 9/2-
T=1.6m
B=255 1/2+
T=3.2m
B=259
T=58m
(1958)

The Sub-Atomic Zoo

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Copyright (c) 1998, 2001, 2003, 2004, 2009, 2012, 2016 Kelley L. Ross, Ph.D. All Rights Reserved

The Periodic Table of the Elements, Note 1

Z is the number of protons, p, in the nucleus of an atom.

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The Periodic Table of the Elements, Note 2

Electronegativity is the power of an atom to capture and hold electrons. High electronegativity, like Fluorine at 3.98, means great power to capture an electron. Low electronegativity, like Potassium at 0.82, reflects a tendency to give up an electron. If electronegativity is very large or very small, atoms will tend to form ions. A strongly ionic bond will form between two atoms with a large difference in electronegativity. If the difference in electronegativity between different atoms is small, covalent bonding will result. The degree of ionic bonding is indicated in the following table:

difference in electronegativity
0.10.20.30.40.50.60.70.80.91.01.11.21.31.4
.5% 1% 2% 4% 6% 9%12%15%19%22%26%30%34%39%
percentage ionic bond character

difference in electronegativity
1.51.61.71.81.92.02.12.22.32.42.52.62.7
43%47%51%55%59%63%67%70%74%76%79%82%84%
percentage ionic bond character

difference in electronegativity
2.82.93.03.13.2
86%88%89%91%92%
percentage ionic bond character

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The Periodic Table of the Elements, Note 3

Crystal Structure
Atoms pack into regular structures called "crystals." Crystal arrangements can be described geometrically as versions of various "space lattices."

This is a facinating area of science where chemistry and geometry meet, recalling Plato's geometric theory of the four elements. More basic lattices occur in general minerology. These are the forms cited for cyrstals of the pure elements. The codes used in the table are the bold three letter abbreviations.

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The Periodic Table of the Elements, Note 4

Mass number A is given for natural isotopes.

Mass number B (= Baryon number) is given for short lived or artificial isotopes.

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The Periodic Table of the Elements, Note 5

, alpha particle emission
, beta particle
, positron
EC, electron capture
IT, transition between isomeric energy states
SF, spontaneous fission

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The Periodic Table of the Elements, Note 6

As an element, "neutronium," neutrons only exist free in neutron stars. Otherwise they decay into, an electron (e-), a proton (p+) -- a Hydrogen atom -- and an anti-neutrino ().

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The Periodic Table of the Elements, Note 7

The size of atoms and ions is an important element in both crystal structure and chemistry. Atoms or ions of the same size pack hexgonally, with either hexagonal or cubic close packing. When some atoms or ions are smaller than others, they may be surrounded by the larger atoms. As they get smaller, fewer surrounding atoms can come into contact with them. The "coordination" number thus gets smaller, and the geometrical shape of the arranged atoms changes.

One consquence of such differences in size can be seen in the system of the mineral feldspar, the most common mineral in the crust of the earth and the moon. Feldspar is basically quartz (SiO2) where some Silicon atoms are replaced by Aluminum atoms. Since Aluminum ions will only have a +3 charge instead of the +4 charge of Silicon ions, the -2 Oxygen ions will result in a net surplus negative charge. This then atrracts positively charged ions. In Feldspar, these will be Potassium, Sodium, or Calcium. Since Potassium and Sodium are chemically similar and tend to form singly charged ions (K+ & Na+), while Calcium is chemically somewhat different and forms doubly charged ions (Ca+2), we might expect Potassium and Sodium feldspars to be chemically different from Calcium feldspar. However, this is not the case. Potassium feldspar (KAlSi3O8) is relatively distinct as Orthoclase, while Sodium (NaAlSi3O8) and Calcium (CaAl2Si2O8) feldspars form the Plagioclase Series, where a smooth transition occurs from pure sodium to pure calcium, with similar cyrstal structure. The key to this peculiarity is the size of the ions. The Potassium ion is very large, at 1.33 Angstroms, while the Sodium and Calcium ions are not only smaller, but of similar size, 0.93 and 0.99 Angstroms, respectively. With the O-2 ion (dominant in the silicates like quartz and feldspar) at 1.40 Angstroms, Potassium ions will form cubic (8x) coordination, but Sodium and Calcium ions will form octohedral (6x) coordination. Silicon +4 ions themselves are only 0.39 Angstroms, and Aluminum +3 ions 0.51 Angstroms, both of which make for tetrahedral (4x) coordination with Oxygen.

The coordination of atom and ion sizes is thus another element in the geometry of chemistry and minerology.

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