Alkali Metals to the LeftLet's go to the left side of the periodic table. When looking for families, the first one you will find is the alkali metal family of elements. They are also known as the alkaline metals. You should remember that there is a separate group called the alkaline earth metals in Group Two. They are a very different family, even though they have a similar name. That far left column is Group One (Group I). When we talk about the groups of the periodic table, scientists use Roman numerals when they write them out. The "one" in this case refers to having one electron in the outermost orbital.
A Family PortraitWho's in the family? Starting at the top we find hydrogen (H). But wait. That element is NOT in the family. When we told you about families, we said that they were groups of elements that react in similar ways. Hydrogen is a very special element of the periodic table and doesn't belong to any family. While hydrogen sits in Group I, it is NOT an alkali metal.
Family BondingNow that we've covered that exception, the members of the family include: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr). As with all families, these elements share traits. They are very reactive. Why? They all have one electrons in their outer shell. That's one electron away from being happy (full shells). When you are that close to having a full shell, you want to bond with other elements and lose that electron. An increased desire to bond means you are more reactive. In fact, when you put some of these pure elements in water (H2O), they can cause huge explosions.
The alkali metals are also metals. That seems obvious from the name. Often, in chemistry, characteristics are assigned by the way elements look. You will find that the alkali group is shiny and light in weight. Their light weight and physical properties separate them from other metals. They are malleable (bendable) and sometimes soft enough to be cut with a dull knife. Alkali metals are not the type of metals you would use for coins or houses.
Innovation Nation: Tiny Batteries (US-NSF Video)