Tag: Science

Oxygen is one of the most fascinating elements for many reasons.  Before we get to it, I first want to point out that the column of the periodic table that starts with nitrogen are called pnictogens, whislt the column starting with oxygen are called chalcogens.  The term pnictogen is recent, dating form the 1950s.  It comes from the Greek plural noun pnikta which means something on the order of “those that are suffocated” in reference to the fact that nitrogen will not support life.  The “gen” part is from the Greek gonos, “born” or “generated”.

Chalcogen comes from the ancient Greek chalkos, meaning “ore” and gonos, and in fact an extremely large number of metal ores contain oxygen or sulfur of both.  Selenium and tellurium are chalcogens that are often found in gold and silver ores.

Time before last we discussed nitrogen and molecular orbital diagrams for it.  If you are not hip to MO diagrams, I suggest you read that part of the link before you try to tackle the MO diagrams for oxygen.

Last time we talked about the unusual properties of elemental nitrogen mostly and how stable it is.  We only touched on a little of the fascinating and extremely complex chemistry of nitrogen, ONCE we can get it in a form other than the incredibly stable elemental form.

This time we shall remedy this, although entire graduate level texts have been written on the subject.  Tonight we shall take a brief survey of the impact that nitrogen has on living organisms, industry, and a few other areas.  We shall attempt to do this by looking at various oxidation states, and nitrogen has more than any other element.

The basic concept is that atoms can either donate or accept electrons from other atoms.  When an atom donates electrons, it is oxidized, and when it accepts electrons it is reduced.  Thus, chlorine bleach works because hypochlorite ion is a strong oxidizing agent and breaks up large, colored molecules to smaller, colorless ones.

I took a week off from blogging last week for a number of reasons.  One was that I was having trouble getting my mind around topics.  Another was being in sort of a strange set of moods that have made concentration rather difficult.  Yet again, and probably the root cause of the other two is either spending large amounts of time with someone (no time to write) or no time at all (no motivation to write).  In any event, I think that I have some balance back.

I got tired of writing about carbon so we shall move on to nitrogen.  With an atomic number (Z) of 7, it is the element after carbon.  Nitrogen is another of the few elements that ordinary people encounter on a daily basis, because it comprises around 78% of the atmosphere of the earth.

There are two stable isotopes of nitrogen, the very common ¹⁴N (99.64%), the rest being ¹⁵N.  Both of these isotopes are formed in larger stars by stellar nucleosynthesis.  Nitrogen is peculiar in that it is one of only five nucleides that are stable with both an odd number of protons and neutrons.  It is really unusual in that ¹⁴N is by far the most common isotope of nitrogen.

Last time we finished our discussion of diamond, and now we move to what is pretty incorrectly called amorphous carbon.  Truly amorphous materials. like glass, have no true crystal structure (although there may be some local microstructures) that repeats regularly.

When used in the sense of carbon, only recently produced thin films of carbon are truly amorphous.  These are of research interest for the most part, although I would be quite surprised if practical uses are not found for them before long.

We shall discuss forms of carbon traditionally called amorphous even though they are not truly amorphous.  These include some of the most commonly encountered forms of carbon, and almost everyone has seen and touched at least a few examples.

Last time we started talking about the allotropes of carbon, finished graphite and began with diamond.  Tonight we shall continue the diamond saga and maybe move to a third common allotrope.

Last week I was having some connectivity problems and, quite frankly, was ill with a bad cold, so I just did not feel much like writing.  I am better (much) this week and my computer seems to be functioning within design parameters.

Since the part that I wrote about diamond was so short last time, I shall paraphrase it as the start of this piece.  That way you do not have to hit the link to get up to speed.

Last time we started our series on carbon, and I now expect it to run for four installments.  Amongst many other properties, carbon is unique in having more allotropic forms than any other element.  Also known as allotropes, these are pure elements with radically different properties.  The term is reserved only for elements, the term for compounds being polymorphs.  An allotrope is a subset of a polymorph.

There is also another distinction:  for an element to have an allotrope, it must exist in the same phase.  Thus, solid lead and molten lead (and lead vapor) are not allotropes, but rather different phases of a given element.

Before we concentrate on carbon, let us consider oxygen.  In the gaseous phase, it has two allotropes, O₂, normal molecular oxygen, and O₃, also called ozone.  For an element as reactive as oxygen, normal molecular oxygen is remarkably nonreactive (wait a few weeks), but ozone is extremely reactive.  But both are just composed of oxygen atoms.

There are only a handful of elements that are absolutely essential to all known lifeforms, and carbon is easily the most important.  Certainly hydrogen and oxygen in the form of water and other compounds are also essential, but without carbon there simply would not be life as we know it.  There are many reasons for that, but that discussion is not for tonight.

This time we shall start at the basics and next time we shall work our way into more complex topics.  Since carbon is so essential and important, this will be a multipart series.  I expect three or so, but that depends on how motivated I am to root around for things that will be interested.

Unlike beryllium and boron, carbon, at least ¹²C, is more common than it should be.  The reason is fascinating, and we shall talk about that tonight.

If you follow this series closely, you will remember that the last element that we covered was lithium, and so the next one should be beryllium.  However, I wrote about beryllium recently and so you can just follow the link.

Last week I wrote about fireworks safety, and my piece was prescient and unfortunately evidently not read by some unfortunate youths in Arkansas.  My friend, who often comments here using the handle justasabeverage, sent me the newspaper article by email the other day that covers the topic after the fold.

This time of year I generally write about fireworks since they are integral to the celebration of Independence Day.  I have written some rather technical pieces in the past, so this time I thought that it might be a good idea to write about some safety factors that users of consumer fireworks should observe.  Even though consumer fireworks are designed to minimize risk of injury, there is a finite probability that accidents and injuries will occur.

Many of you know how much I enjoy the music of The Who, and I shall work them into this piece.  It happens to involve one of the most treacherous pyrotechnic composition, flash powder.  In a former life, I was a professional pyrotechnician, and I am still scared of flash powder.

Many accidents involving consumer fireworks are either personal injuries caused by negligence (often alcohol fueled), ignorance, or bravado (also often alcohol fueled).  Many other accidents involving these products have to do with unintentional fires cause by firework use, storage, or transport.

Lithium, the element with the atomic number (Z) of three, is as old as the universe.  It, along with hydrogen and helium, were formed at the time of the Big Bang, making it primal indeed, although much of the lithium that we encounter was synthesized in stars.

Lithium is much less common in the cosmos than it should be, and that is in part due to the fact that the two stable isotopes, ⁶Li and ⁷Li, are much less stable than many other light nuclei.  This might sound contradictory, but there is a property of atomic nuclei called binding energy per nucleon that measures the stability of nuclei.  Both stable isotopes of lithium have binding energies per nucleon lower than any other nuclei except for deuterium, tritium (which is radioactive), ³He, and of course hydrogen which has a zero binding energy because there are no neutrons to require binding.

Helium is one of the elements that most people see (well, not see since it is a colorless gas) in everyday life.  We are familiar with it because it used to fill toy balloons so that they rise in air.  We shall get around to the calculation about that later.

Helium also is used for large balloons, blimps, and dirigibles for the same reason:  it is lighter than air and so provides lift (not aerodynamic lift, which is provided by air passing over a wing surface) and so causes objects to rise, but these large craft have a payload where toy balloons do not, at least in most cases.

We also know it as the gas that causes voices to take on a bizarre, high pitch.  We shall also discuss the reasons for that.  But for me at least, helium is of extreme interest because of its quantum mechanical properties.

Last time we had a rather technical discussion about the biology and chemical mechanics of fireflies.  I appreciate all of the comments, and some of them indicated that I should expound a bit.

Most of the comments were concerned with firefly ecology and how to encourage their numbers.  It is true that fireflies seem to be on the decrease insofar as populations go, and there are several reasons for that.

One reason that I am pretty much sure DOES NOT deplete the population is live capture, with or without release.  I have a call in to Sigma-Aldrich to see if they still buy fireflies.  If so, they are supplying lots of material for research whilst doing little harm to the population.

It is HARD to catch enough fireflies to damage the population!  As I get more information about the bounty, if any, on members of the Photinus genus, I shall share.