When I first walked into my Chemistry class, I remember seeing a multitude of test tubes and posters galore. Visions of blowing stuff up and making beakers overflow with dangerous chemicals danced pleasantly in my head. On one wall of my professors class room was the biggest periodic table I had ever seen. Each element’s square measured 4 x 4 inches, and with over 100 squares…well, you can imagine just how big it is.
I love the color coded periodic tables. They make quick glances even quicker and provide a bit of excitement to a class that is known to be dull. If you look at a periodic table, the farthest column on the right, contains the alkali metals. The elements in this column include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Ceasium (Cs), and Francium (Fr). (Though hydrogen is in the very same column as the alkali metals, it rarely exhibits behavior similar to the alkali metals; mostly because it is a gas, not a solid)
There are, obviously, similarities between the alkali metals. The two most obvious are listed below:
1. Alkali metals are highly reactive. A great, and most commonly used example of their reactivity is shown by dropping a bit of potassium in a cup of water. In this reaction, enough energy is used to ignite the potassium and cause it to project itself across the water’s surface. If this same experiment is conducted with rubidium or ceasium, you will receive a much more violent reaction.
2. Alkali metals are rarely found naturally in the environment. Lithium, while not being necessary for any biological function, can be found in teeny tiny amounts in the umbilical cord. Rubidium is also not known to be useful in any biological function, and yet it is found in marine life forms in northern lakes(Lake Erie and 2 Arctic lakes). The rarest of all alkali metals is francium. It is believed that at any moment, less then 1 ounce of francium exists on the entire planet.
The alkali metals demonstrate the amazing group trends in the periodic tables. From the boiling and melting point decrease from lithium to francium while the atomic weight increases.
