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Hopefully this will be a little bit better than the one last night, since I am almost finished with my taxes (boo, I have to send some money, but not a lot).

The elements in Group IIA are know as the "alkaline earth" elements, and include beryllium, magnesium, calcium, strontium, barium, and radium.  Except for the first and last, I bet you have been exposed to them.

The outstanding characteristic of all of these elements is that they have two electrons in their outer shell, in the "s" orbital.  This gives them stability relative to the IA metals, the alkali metals, that I treated very briefly yesterday (I will make up for that some time).  However, since all of these elements are in the the second row or later, there are three "p" orbitals that are unoccupied in the same shell, so they are not inert.

Remember, atoms want to have completely filled orbitals, or completely empty ones.  Thus, alkaline earth elements either need to lose two electrons or gain six to populate the appropriate orbital.  The IIA metals have better energetics by losing the two.

Let us look at each.

Beryllium is not typical, since it is a little bitty atom with only the K shell electrons to shield the L ones, so the L electrons are rather tightly bound.  Beryllium is a metal, and a very lightweight one.  It also has a large heat capacity (another function of its electronic structure and low mass nucleus).  If you look at very old texts, you will find that its name is Glucinium, because its soluble salts are sweet to the taste.  Never try it, because beryllium salts are extraordinarily toxic.  Uses for this element include being an alloying agent in copper alloys (those alloys are good electrical conductors and very springy), as a heat sink for technical uses (they used to think that it would be great on spaceships), and as a gem.  True emerald is a complex compound with a good amount of beryllium.  The mineral known as beryl is emerald with impurities, and it is the ore.  Most folks, except those who have emeralds, never touch beryllium, nor should they.

Next is magnesium, and it is well known.  Anyone that had a Lawn-Boy mower back in the day was in awe of the stiff and light deck of the mower.  Is was cast magnesium, with a bit of alloying to make it stiffer.  Magnesium is very common, and is refined mostly from seawater after removing the sodium and calcium.  It is very, very light and strong, and is excellent for applications where it is not apt to be ground up and ignited.  Anyone who has seen a burning ribbon of magnesium will agree that it combines with oxygen very readily, with a tremendous liberation of energy.  Magnesium also is the central atom of chlorophyll, and so in a sense feeds us all.  Chlorophyll without magnesium would be like hemoglobin without iron, and the chemical structures of the two are more similar than you would expect.  You find magnesium commonly, other than lawn mower decks, in Epson salts, with is a hydrated magnesium sulfate.  For those of you who have school students, growing large magnesium sulfate crystals is not not difficult.  Just make a saturated solution in warm water (distilled is best), put it in a styo cup, and hang a piece of thread into it.  Slow evaporation will make very nice crystals.

Now to the third row, and calcium.  If you have bones, you contain calcium.  It is common and essential.  Rome was built with it.  The Romans learnt to use volcanic ash with some additives to make concrete.  The basic unit is calcium and silicon, with carbon dioxide from the atmosphere to harden it.  All limestone and marble are oxides in one way or another of calcium.  This element has a special affinity for carbon dioxide, and so may save us if we use is correctly.  It is also an important neurotransmitter in you body.  The parathyroid glands mediate it, and if it goes off balance, you will be very ill.  It is also a soil builder and serves to "sweeten" (make more basic) acidic soils.  I could spend 50 pages about calcium, but need to move to the next one.

Near my favorite is strontium.  It is taken up in the body just like calcium, and that is what makes nuclear fallout so dangerous, because the radioactive isotope, 90, goes to the bones and irradiates the blood producing cells.  But natural strontium is not so harsh.  It does not have much use except for the brilliant red (carmine) color that it brings to fireworks.  If you have ever seen red fireworks, it is likely that it was the dropping of an electron from an excited state back to the ground state.  Everything is physics.

Now my friend barium, which is considered as a heavy metal.  Barium is quite toxic, in soluble form.  But the sulfate is not much digested, so a barium swallow or enema will not give you barium poisoning.  The reason that they use is it that the sulfate is very insoluble and the barium has a high atomic number, so that X-rays do not pass.  My favorite use of it is to make wonderful green effects in fireworks, when combined with potassium chlorate.  But I like pyrotechnics, and know what I am doing.

Now Radium.  Same properties as Barium, but extremely radioactive.  I do not want to hold any, because the definition of radiation is based on radium. I would bet that it has a pretty flame, but I am not ready to see.

Warmest regards, Doc.

Originally posted to Translator on Tue Apr 08, 2008 at 07:41 PM PDT.


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