Iris Levine age 13, of Los Angeles, Calif, for her question:

What is an alkali?

We borrowed the word alkali from the Arabs, to whom it meant the ashes of the saltwort plant. Before the age of modern chemistry, certain soluble salts taken from plants were called alkalies. Potassium carbonate, taken from wood ashes, was used to make soap. Sodium carbonate, often taken from burned seaweeds, was used in the making of glass. Nowadays we know more about the basic nature of these chemicals and the word alkali takes us right to the periodic table of the basic chemical elementsd

This wonderful chart shows us at a glance which of the basic element are related. The elements we want are in the very first upright column. These dramatic chemical cousins are called the alkali metals. Since w e find them listed in the same column, we know that they have certain chemical features in common and we can expect them to behave in much the same way, All of them are silvery white metals soft enough to be cut with a knife. All of them are extremely active when it comes to reacting with other elements,

At the top of the column is hydrogen which, though it has one feature in common with its cousins, does not act like them. Next is lithium, then sodium, potassium, rubidium, cesium and francium. Francium is a radio active element with a half life of only 20 minutes, The other five are the very active alkali metals. Each element in this column has a single electron in its outer shell which is always eager to take part in chemical reactions with other elements.

The two most important alkali metals are sodium and potassium. We find a hint of them in the old time alkalis potassium carbonate and sodium carbonate. Sodium makes up 2.6 per cent of the earth’s crust and potassium makes up 2.5 per cent   yet we never see them. They are always found in combination with other element, Neither of them could remain pure in air or moisture.

Pure sodium, a. soft silvery metal, reacts violently in cold water and rusts in the air. In the laboratory it is preserved in a bath of kerosene, If we drop a small lump of this alkali metal into a flask of chlorine gas, we shall see some fast action. The sodium and the chlorine will combine to form sodium chloride   table salt, Aside from our daily diet, this chemical has a long list of chores in industry.

Pure potassium is also a soft metal and even more dramatic when dunked in water. It gives off enough heat to light little blue flames of hydrogen on the surface, Potassium carbonate is but one of the useful chemicals to come from this alkali metal. This compound is used to harden certain types of glass.