22Aug 2014 by Vincent Summers No Comments

Explaining Saturation and Unsaturation

Chemistry
What is Saturation? What is Unsaturation? Even those scientifically uninclined use the words. Saturation, unsaturation, and polyunsaturation are dietary terms closely associated with health. Most know they are also chemical terms. But they don't understand what they mean. This is a shame, since "saturation" can be easily understood by any bright student. Saturated Hydrocarbon Linkage Living matter (plant or animal) is made of of organic compounds. These include (but are not limited to) fats, carbohydrates, and proteins. All these substances contain a kind of backbone or chain, of atoms of carbon (C) bonded to atoms of hydrogen (H). Each carbon is capable of bonding with four hydrogens. [sc name="MidArticleAdsense"] For purposes of illustration, we'll assume we have before us a chain of four carbon atoms, with every available bond possibility…
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21Aug 2014 by Vincent Summers No Comments

Cubane: The Chemist’s Toy?

Chemistry
Cubane is an organic hydrocarbon. It consists of carbon and hydrogen and is cubic in shape. It is a very curious substance, indeed. With no practical purpose in view, it was first prepared in 1964. There is an endless number of theoretical molecular possibilities in the world of organic chemistry. Some chemicals are simple. Others are complex. Some are of practical use to mankind. Some are mere toys of the intellect. Yes, adults must have their toys! Cubism "We do the difficult immediately. The impossible takes a little time." Chemists enjoy challenges. One challenge was to synthesize cubane (C8H8). It is a cut with a carbon atom at each corner. Attached to each of them is one hydrogen atom (see the image). Now carbon "prefers" to form angles of 109.5…
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20Aug 2014 by Vincent Summers 6 Comments

Cesium Auride – Relativistic Electrons?

Chemistry
[caption id="attachment_7305" align="alignright" width="440"] Imagine relativistic electrons.[/caption] Strange isn't the word for cesium auride. Gold in liquid form? Indeed, yes! Discovered more than a half century ago, the properties of this cesium and gold compound are not yet fully understood. There are all sorts of curios in chemistry. Chemists love them dearly. I still remember one particularly strange molecule. It was affectionately named hexamethyl bathroom tile. Free Lectures Recently I listened to some free online chemistry lectures. They were produced by MIT under its OpenCourseWare program. One of those lectures spoke of an alloy of cesium and gold that acts like a salt, cesium auride. Key to its forming is the difference in electronegativity between cesium and gold. It is roughly the same as the difference between sodium and iodine!…
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20Aug 2014 by Vincent Summers No Comments

What Happens at Absolute Zero?

Physics
[caption id="attachment_7397" align="alignright" width="440"] Bose-Einstein condensate at billionths of a degree. Image by NIST[/caption] Classical physics suggests that at absolute zero, particles cease all motion. But what about quantum mechanics, the science of the very small? Ah, therein lies the rest of the story. From Gas to Frigid Solid It is well established fact that heated gas atoms or molecules move with great vigor. In fact, gas expands as energy increases, due to increased particle momentum. The reverse is also true. Cool a gas and it shrinks. Particle motion decreases. Particle momentum decreases. The atoms or molecules come closer together. At some point a liquid forms. Cool the liquid further and the result is a solid. Keep cooling the solid, and in theory it is possible to reach the coldest…
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18Aug 2014 by Vincent Summers 3 Comments

The Ammonia Flip, Quantum Tunneling and Oscillations

Physics
[caption id="attachment_25040" align="alignleft" width="400"] Image U..C. Davis[/caption]Unexplained by classical mechanics, the ammonia flip occurs when an ammonia molecule flips like an umbrella... Quantum mechanics explains how some phenomena occur which are not part of everyday experience. The ammonia molecule can flip when ordinary logic suggests it should not be able to do so. When most people think of ammonia, they think of a household cleaner. Actually, ammonia is a gas. The household cleaner is a dilute solution of that gas in water. Chemists would call that ammonium hydroxide. Ammonia has the very simple chemical formula, NH3. That's the formula; but what's its structure? How would you draw it? Would you draw it like an airplane propeller with the nitrogen being the hub and the tips of the three blades the…
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18Aug 2014 by Vincent Summers No Comments

Factors that Complicate Atomic Mass Determination

Physics
[caption id="attachment_8319" align="alignright" width="440"] Nucleus - CC-SA-3.0 by Marekich[/caption] Modern chemistry depends a good deal upon accurately knowing the atomic mass of each of the elements. What factors complicate determining those values? Each of the approximately 90 different natural-occurring elements possesses a nucleus or central core of protons and neutrons, in addition to electrons that orbit around the nucleus. It is important to the chemist or physicist to know the total mass of each element. Can correct values be obtained simply by summing the weight of individual particles in an atom? After all, each of these particles has a precisely known mass. The answer is, No! Such calculations disagree with experimental measurement. An example illustrates the point. Consider Helium-3 An atom of helium-3 has two protons, one neutron, and two…
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