I picked strontium because I had never heard of it before and learned from Wikipedia that coral use this element to build their exoskeletons. Sealife is interesting to me and I like to imagine being an ocean dweller, so now I will relay what I learn to you about Strontium.
The periodic basics: It's in the second column on the P. Table right in the middle of all the other alkali earth metals. Like all of these elements, Strontium is also a soft metal that reacts with halogens to form ionic salts and with water to form alkaline hydroxides. The point here is that it is reactive (two electrons in the valence shell means it will try to lose those electrons to become a doubly charged positive ion). It's atomic number is 38 and its atomic weight is close to 88.
While Strontium is actually kind of a metalic white color, because it is so reactive it changes color when it hits the air and looks yellowish. It is softer than calcium. This fact is making me curious about the element's place in exoskeltons. But I suppose I will find out why in a minute if I can be patient. A fun little fact for those who like explosions: if strontium is finely powdered and exposed to air at room temperature, it will spontaneously combust. Yay, Strontium. What a dramatic trick. And, when it burns it makes the fire burn a crimson color. How lovely. Someone noticed this beautiful trick and now these volatile salts are used in the production of flares and in pyrotechnics (specifically, it causes the red color in fireworks).
Another interesting fact about this all-too-ignored element is that it is used in a compound with aluminium in the glass of your color TV's cathode ray tube to prevent X-ray emissions. What would happen without it? I don't know.
Medically, Strontium can be incorporated into bone because it acts like calcium. It has a bunch of other interesting uses, but they are a little difficult to understand exactly. For example, Strontium atoms are being used in an experimental atomic clock that has "record-setting accuracy."
It might also be found in your toothpaste. Or mine. I hope the tube doesn't blow up. Then again, that'd be kind of cool if it did. But messy.
The mineral strontianite was found in Strontian, in Scotland. Strontium is found in strontianite, as well as in celestine. Strontium is the fifteenth most abundant element on earth. Can you believe that? Have you ever heard of it? I really don't think I have! China has most of the world's strontium. Spain and Mexico have a lot, too.
Another interesting thing about Strontium is that it doesn't occur naturally, but needs to be coaxed into its elemental state through some chemical processes. It also has a lot of different isotopes that are used in many very diverse ways. It is a product of nuclear fallout and therefore can be very dangerous because it immitates calcium and the body does not release it. They say it is sparklier than a diamond -- at least that's what I think this means: "Strontium titanate is an interesting optical material as it has an extremely high refractive index and an optical dispersion greater than that of diamond." But diamonds are harder, and Strontium is soft, therefore if you wore it as a gemstone in a ring it would probably smush.
Okay, so I'm almost done here. But maybe I missed something in my life -- specifically, news of Strontium. Here is the opening paragraph from an article titled "Strontium: Breakthrough Against Osteoporosis:"
"Mention strontium to most people, and they will almost always immediately think of strontium-90, a highly dangerous, radioactive component of nuclear fallout produced during atmospheric testing of nuclear weapons in the 1950s. As a result of above-ground nuclear testing, radioactive strontium spread throughout the environment and contaminated dairy products and other foods, and subsequently accumulated in the bones of both children and adults."
So maybe everyone but me has heard of this crazy element. I still haven't found out the bit about the coral yet. The whole article about Strontium's medical uses is here: http://www.worldhealth.net/news/strontium_breakthrough_against_osteoporo and actually pretty interesting.
2. Avogadro's Hypothesis link:
http://www.carlton.srsd119.ca/chemical/molemass/avogadro.htm
That was a lovely, straightforward and clear little web page. I did well on their quiz (was it for fifth graders?) which made me happy. What I took away from this website was how frustrating it must have been for those chemists all those years working off of Dalton's incorrect assumption that atoms from an element could not form a molecule and that everything had to be combined in a 1:1 ratio, yet they were not seeing anything left over. How crazy-making would that be??!! Thank goodness they finally realized that Avogadro was right. How surprising that someone else did not continue to keep his hypothesis in obscurity and decide to take credit for themselves (like the Marconi / Tesla radio debate). Very honorable to name it after Avogadro. I'm also wondering: did he really look like that?
3. What is a mole? Review of the link: http://www.ceramic-materials.com/cermat/education/111.html
I was following the web page along very nicely until the middle. Then I got confused so I consulted another source. A mole is the same number of particles found in 12 grams of carbon-12. There are 6.02 x 10exp23 particles in 12 grams of carbon 12. So a mole is a unit of measurement that equals 6.02 x 10exp23. What I am confused about now is the question "How many molecules are in one gram of a gaseous element?" I thought the link was leading us to the answer to this question, but now I am confused.
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