Sunday, December 16, 2007

The Elements

For those of you just joining us, I post on a variety of subjects: Dinosaurs, Astronomy, History... Things that have a sort of universal interest. I've been moving through the Periodic Table, posting on each element. The atoms described here make up our entire universe.
Previously, they've all been on chemicals most people have heard of. Tonight, with Scandium, we begin seeing chemicals I knew nothing at all about until researching them for Hansisgreat. Therefore, consider:

Potassium:
Atomic Symbol: K
Atomic Number: 19
The name is derived from the English word potash. The chemical symbol K comes from kalium, the latin for potash. Potassium is an essential element for almost all living things, except possibly a few bacteria.  Because one of its commonly occurring isotopes is radioactive, it has been suggesting that potassium may be responsible for natural genetic mutations in plant and animals.
Around 2500 potassium atoms disintegrate in the human body each second.
It is not generally appreciated that the need for potassium in the diet is much greater than that for sodium salts. Eating one banana per day greatly increases life expectancy, and would save billions of dollars per year in health care costs associated with high blood-pressure.

Calcium:
Atomic Symbol: Ca
Atomic Number: 20
Calcium is also essential to practically all living things. As calcium carbonate, it provides the skeleton for most marine creatures and the lens in the eye; as calcium phosphate, it is found in the bones and teeth of land-based animals.
We tend to think of bone as somehow different from the other cells that make up our body. It is more like a mineral than living flesh, but it is just as "alive" in that it is endlessly changing, being constructed and broken down at millions of sites throughout the skeleton by cells called osteoclasts.
Lime (calcium oxide, CaO) has been used since ancient times to make mortar for building. Cement is made by mixing limestone and clay in a kiln and heating it. When it is mixed in water, cement undergoes a complex series of reactions which have only recently been understood.

Scandium:
Atomic Symbol: Sc
Atomic Number: 21
When the periodic table of elements was developed by Dimitri Mendeleyev in 1869, he noticed that there was a large difference in the atomic weights between calcium (40) and titanium (48). He therefore predicted that there should be another element of intermediate atomic weight.
Scandium was discovered 10 years later, in 1879, by Lars Frederick Nilson of Uppsala, Sweden. He extracted it from euxenite, a complex material containing the ores of eight metals. He believed it could only be found in Scandinavia, and therefore called the newly discovered metal scandium.
Industrial uses are similar to those of aluminum, but scandium is much more costly. It's used in baseball bats to give them added striking power, and in racing bicycle frames since it's strong and lightweight.

If you'd like to see my posts on the previous elements, click here.

There's an excellent book called Nature's Building Blocks: An A-Z Guide to the Elements, by John Emsley. A necessity for the casual chemistry enthusiast.

1 comment:

Evan said...

I love your scientific posts.

Seems like we share the same interests. =)