Dating radioactive elements
By the late 1700s, chemists were reasonably sure that both potash and soda ash contained elements they had never seen.They tried to think of ways to break these compounds down into their elements.The main difference between them was the source from which they came.It was not until the eighteenth century that chemists understood the difference between potash (vegetable alkali) and soda ash (mineral alkali). If you have looked at a periodic table, you may have noticed that the atomic mass of an element is rarely an even number. If you are an atom with an extra electron, it's no big deal. As you learn more about chemistry, you will probably hear about carbon-14. C-14 is considered an isotope of the element carbon.We have already learned that ions are atoms that are either missing or have extra electrons. They are just a little different from every other atom of the same element. Electrons don't have much of a mass when compared to a neutron or proton.Let's say an atom is missing a neutron or has an extra neutron. An atom is still the same element if it is missing an electron. For example, there are a lot of carbon (C) atoms in the Universe. Atomic masses are calculated by figuring out the amounts of each type of atom and isotope there are in the Universe.
The loss of those neutrons is called radioactive decay. For carbon, the decay happens in a few thousand years (5,730 years).
Common household lye (such as Drano) is a typical alkali.
The chemical name for potash is potassium carbonate (K ).
(See sidebar on Davy in the calcium entry in Volume 1.) There are very few uses for potassium as a pure element.
However, compounds of potassium have many important applications, the most important of which is as a fertilizer.
The alkali metals also include lithium, sodium, rubidium, cesium, and francium. Potassium is so active that it never occurs free in nature.