Valences of the Elements

Chemistry of the Periodic Table

Many people believe that the valences of the elements are those which can be derived by looking at the Groups (columns) of the Periodic Table. It is true that these are the most common valences, but the real behavior of electrons is less simple. Here is a listing of element valences. Remember that an element's electron cloud will become more stable by filling, emptying, or half-filling the shell. Also, shells don't stack neatly one on top of another, so don't always assume an element's valence is determined by the number of electrons in its outer shell.

Number	Element	Valence
1	Hydrogen	(-1), +1
2	Helium	0
3	Lithium	+1
4	Beryllium	+2
5	Boron	-3, +3
6	Carbon	(+2), +4
7	Nitrogen	-3, -2, -1, (+1), +2, +3, +4, +5
8	Oxygen	-2
9	Fluorine	-1, (+1)
10	Neon	0
11	Sodium	+1
12	Magnesium	+2
13	Aluminum	+3
14	Silicon	-4, (+2), +4
15	Phosphorus	-3, +1, +3, +5
16	Sulfur	-2, +2, +4, +6
17	Chlorine	-1, +1, (+2), +3, (+4), +5, +7
18	Argon	0
19	Potassium	+1
20	Calcium	+2
21	Scandium	+3
22	Titanium	+2, +3, +4
23	Vanadium	+2, +3, +4, +5
24	Chromium	+2, +3, +6
25	Manganese	+2, (+3), +4, (+6), +7
26	Iron	+2, +3, (+4), (+6)
27	Cobalt	+2, +3, (+4)
28	Nickel	(+1), +2, (+3), (+4)
29	Copper	+1, +2, (+3)
30	Zinc	+2
31	Gallium	(+2). +3
32	Germanium	-4, +2, +4
33	Arsenic	-3, (+2), +3, +5
34	Selenium	-2, (+2), +4, +6
35	Bromine	-1, +1, (+3), (+4), +5
36	Krypton	0
37	Rubidium	+1
38	Strontium	+2
39	Yttrium	+3
40	Zirconium	(+2), (+3), +4
41	Niobium	(+2), +3, (+4), +5
42	Molybdenum	(+2), +3, (+4), (+5), +6
43	Technetium	+6
44	Ruthenium	(+2), +3, +4, (+6), (+7), +8
45	Rhodium	(+2), (+3), +4, (+6)
46	Palladium	+2, +4, (+6)
47	Silver	+1, (+2), (+3)
48	Cadmium	(+1), +2
49	Indium	(+1), (+2), +3
50	Tin	+2, +4
51	Antimony	-3, +3, (+4), +5
52	Tellurium	-2, (+2), +4, +6
53	Iodine	-1, +1, (+3), (+4), +5, +7
54	Xenon	0
55	Cesium	+1
56	Barium	+2
57	Lanthanum	+3
58	Cerium	+3, +4
59	Praseodymium	+3
60	Neodymium	+3, +4
61	Promethium	+3
62	Samarium	(+2), +3
63	Europium	(+2), +3
64	Gadolinium	+3
65	Terbium	+3, +4
66	Dysprosium	+3
67	Holmium	+3
68	Erbium	+3
69	Thulium	(+2), +3
70	Ytterbium	(+2), +3
71	Lutetium	+3
72	Hafnium	+4
73	Tantalum	(+3), (+4), +5
74	Tungsten	(+2), (+3), (+4), (+5), +6
75	Rhenium	(-1), (+1), +2, (+3), +4, (+5), +6, +7
76	Osmium	(+2), +3, +4, +6, +8
77	Iridium	(+1), (+2), +3, +4, +6
78	Platinum	(+1), +2, (+3), +4, +6
79	Gold	+1, (+2), +3
80	Mercury	+1, +2
81	Thallium	+1, (+2), +3
82	Lead	+2, +4
83	Bismuth	(-3), (+2), +3, (+4), (+5)
84	Polonium	(-2), +2, +4, (+6)
85	Astatine	?
86	Radon	0
87	Francium	?
88	Radium	+2
89	Actinium	+3
90	Thorium	+4
91	Protactinium	+5
92	Uranium	(+2), +3, +4, (+5), +6

Reference: Lange's Handbook of Chemistry, 8th Ed., Norbert A. Lange (Ed.), Handbook Publishers, Inc. 1952.

I can never forget this great man

While I was struggling to find out a method related to spectroscopic technique in Computational Chemistry, many Indian Scientists deliberately delayed disclosing the same for reasons better known to them. Quite reluctantly I just shot a mail to PvR Schleyer (on whose references I built up my PhD thesis) and wanted to forget the whole episode of requesting with our fellows. And to my surprise, I got a reply from him in minutes!!! He did not know me, but for the sake of 'humanity', perhaps, he elaborated the technique with an example!

He has died a few days back, on 21st November, at his home in Ila, Georgia, US.

He has published 1271 papers and is the third most cited Chemist in the world of Modern day chemistry. Paul von Ragué Schleyer, 84, a towering figure in physical organic chemistry and a chemistry professor at the University of Georgia, in Athens is no more.

Delving into a broad range of physical organic, organo-metallic, inorganic, and theoretical chemistry topics, Schleyer made vast contributions, including discovering ways of synthesizing adamantane and other cage molecules by rearrangement. He also identified new types of hydrogen bonding, elucidated solvolysis mechanisms, and expounded on the nature of reactive intermediates.

Schleyer discovered new molecular structures, particularly those involving lithium and electron-deficient systems. Most recently, he focused on nuclear magnetic resonance, aromaticity, and planar hypercoordination of carbon and other elements.

His home page: http://schleyer.chem.uga.edu/ 

You are here - Chris Hadfield - Review

Around the world in 92 Minutes!

We have read "Around the world in 80 days", and at first this title appeared a sequel to that. But it is not so. The vintage book is about sea voyage and has many fictitious characters and incidents.

This one is real. Hadfield has done extensive research after taking about 45000 pictures from the ISS and has chosen only the best and intriguing ones. The book is very simple and dwells on the nature of the Earth's structure and has many historical references as well.

The book shows our home, our city, country, continent, our whole planet - from a unique perspective. It was actually Chris's Twitter feed from the ISS. This photo documentary shows us we didn't really understand what we saw from his tweets. We caught the beauty but missed the meaning. Curated from images never before shared, Chris's big picture reveals why our planet looks the way it does and why we live where we do. Chris sees more in these images than we do, not just because he's spent months in space but because his in-depth knowledge of geology, geography and meteorology allows him to read the mysteries the photos reveal.  His most beautiful explanation I liked was over the eye of the Sahara Desert - The Richat Structure in Mauritiana.

Present tweets from Alexander Gerst and Reid Wiseman (returned 10th Nov, 2014) also conform to this fact, but Hadfield has made a mark.

If you want to see how the world really looks like from a height of about 450 Km, and appreciate the art work of our Creator, then this book is for you. Enjoyed every photo and the fascinating commentary.

You Are Here: Around the World in 92 Minutes: Chris Hadfield, Random House Canada

Brilliant Blunders - Mario Livio - Review

Mistakes are portals of Discovery! Review

Mario Livio explores some of the most brilliant blunders in the history of science, but with a pinch of excessive elaboration, at least for those who are already aware of Darwin's ignorance of Mendel and Einstein's utterance about cosmological Constant.

While there are no shortage of legitimate mistakes in science , Livio focuses instead on what a handful of high-order blunders. The following are the main blunders that form the crux of this book:

1. Charles Darwin's theory of evolution conflicted with the understanding of heredity in his day: In the mid-1800's, before Mendel's experiments showed how heredity worked, scientists (including Darwin himself) believed that heredity worked by combining traits. So, for example, if you had a white moth and a black moth, if they mated then this would result in a gray moth. Unfortunately, this sort of heredity doesn't actually provide an environment in which his theory of evolution can really work, because any benefits from natural selection would eventually fade away in the background of the population.

2. Lord Kelvin's estimate of the age of the Earth: Using basic principles from physics and thermodynamics, Lord Kelvin estimated the length of time it would take for the newly-formed hot Earth to cool down into the temperature it is today. This theory assumed that there was no convection beneath the Earth's crust. His blunder is that when this was pointed out, he refused to even realistically consider that a fluid, melted core was a possibility! His prediction was drastic.

3. Linus Pauling almost discovered the double helix structure of DNA, but made a basic chemistry mistake in the model: The resulting model - created in haste in an effort to pre-empt publication by others. When Watson & Crick saw the flawed model, they rushed to get their model completed in time to beat Pauling to publication!

4. Fred Hoyle refused to abandon his steady state theory well after there was sufficient evidence to refute it: In an effort to avoid an origin predicted by the big bang theory, Fred Hoyle suggested a process of continual matter creation throughout the universe, called the steady state theory. The theory itself was perfectly reasonable when proposed, but as evidence mounted against it (such as the discovery of the cosmic microwave background radiation), Hoyle refused to acknowledge that his theory might be wrong and kept adjusting the theory in attempts to keep it viable.

5. Albert Einstein's introduction of the cosmological constant into general relativity: One of the first solutions to Einstein's equations of general relativity showed that it allowed for a universe that was expanding or contracting. To fit with his ideal of a static universe, Einstein introduced a term into the equation (allowed but not required by theoretical considerations) which kept the universe constant, neither expanding nor contracting. However, when Edwin Hubble discovered evidence that the universe was expanding, Einstein no longer saw it as necessary, so set the cosmological constant to 0. In 1998, evidence arose which suggested that some mysterious dark energy is causing the universe to expand, meaning that Einstein's cosmological constant may actually have a non-zero value anyway ... something that several of Einstein's peers suggested at the time. Livio also spends considerable time describing his investigation into the claim that Einstein called the introduction of the cosmological constant his "biggest blunder" ... and finds it wanting.

The book is a good narrative of these key moments in the development of science. The different blunders reveal the way science progressed and evolved.

The first part of the book, on Darwin's blunder is a bit too involved with genetics and forces a dry discussion. You must keep interest in the 'blunders' so that you pass through Kelvin's and finally reach Einstein. The later part of the book is interesting relatively and the best thing I found in this book is the 'Reference' the author has covered - a whopping >20% of the book itself!!

Hyperspace: A Scientific Odyssey Through Parallel Universes, Time Warps, and the 10th Dimension - Michiu Kaku - Review

Written in a simple manner Kaku takes us on a journey from finite to infinite with reasons. The entry into dimensions 1,2,3,4....10 is very lucid and with several proofs he makes us believe that there may be more dimensions we might 'think', particularly about light which has many peculiar properties (including the fastest wave) as a fall out of interacting dimensions. He reasons it with a fact that the electromagnetic radiations are every where and such a huge amount of radiation cannot exist without its own 'space'. We just do not have the 'equipment' to see these dimensions.

The talk of Mobius strip and Flatland (a book by Abbott E Abbott is referred) caught my attention. If we were in 2D only we would see only shadows.Nice. If you lived in a flatland and were folded into a Mobius strip and made to traverse you would probably see your heart moved from left side of the chest to right!

The matrix to describe super symmetry using Einstein, Maxwell and Yang-Mill is excellent (Gravity and light, Nuclear Force and Matter), the result of which could be leptons and muons. (just like bosons and fermions)

The importance of geometry is laid like this
Geometry —> field theory —> classical theory —> quantum theory
So, he seems to suggest we 'cook' up all the geometries of the molecules and materials and have enough evidence for such support using quantum theory, the development of which alone is the basis of all advanced materials science.

He pays rich tribute to many forgotten scientists and also mentions Srinvasan Ramanujan as to have come across some strange parameters amounting to 10 numbers which if assigned 10 dimensions could well solve the problem he proposed (Number Theory), using present day super computers.

The book can be sensed in two parts
First half of the book is the history of hyperspace, second half is what can come out of the theory and is a little bit uninteresting wherein Kaku expresses Sociology and Civilization along with COBE, Wormholes, Dimensions and Mathematics Time machine and blue print for it. A few good anecdotes like this one from Aquinas about Creator is catching:

Things are in motion, hence there is a first mover
Things are caused, hence there is a first cause
Things exist, hence there is a creator
Perfect goodness exists, hence it has a source
Things are designed, hence they serve a purpose

A good book for science lovers and even those who think they have no good science background can find this book interesting.

Kepler’s second law holds that a line segment connecting an orbiting planet to its sun sweeps out equal areas in equal periods of time: In the diagram above, if the time intervals t are equal, then so are the areas A.

If gravity were turned off, would this still be true?

(Below Picture) Yes. The planet would pass into space in a straight line, and each time interval would define a triangle with height h and base t. Since a triangle’s area is half the product of its height and base, they’re all equal.

Why Does the World Exist : Jim Holt - Review

The central theme of the book being "Why is there something rather than nothing", made an attractive start up. The author has interviewed about 50-60 illustrious personalities like John Updike, David Deutsch, Adolf Grünbaum, John Leslie, Derek Parfit, Roger Penrose, Richard Swinburne and Steven Weinberg (has missed mentioning Abuds Salam for the theory both were credited). A few have taken the question seriously and a few sarcastically. The answers are not objective and have run into descriptive pages which are interesting. After a few chapters (like 5 or 6 out of 25), the interest wanes as some philosophical points diffuses into unnecessarily drifted topics (away from the central theme). There is mention about Buddha, Imam Ghazali and the 'invention of zero' by 'Hindu' as Shunya.  Platonic World and Multiverse are a few new things I learnt here. 

A few 'questions' have been the answer for his questions; for the Big Bang : What banged? and Why did it Bang? What is Life without numbers? Where do all roads lead to? "What is it that breathes fire into equations and makes a universe for them to describe?  Why does the universe go through all the bother of existing?" etc.

For those who would like to go in search of understanding Universe (and no one has so far understood), this book may prove to be an ontological sojourn of refreshment for brain. Quite a few books have come out good on theory of Universal existence, but no one has ever touched on the topic "mother". His narration of how he sees his mother facing cancer and later death makes an interesting reading. Her mother had even won a local Tennis tournament a few years before her death and his love for the mother is reflective in his last part of the book where he does not say she died, but was transferred!