The metals in Group IA (Li, Na, K, Rb, Cs, and Fr) are called the alkali metals because they all form hydroxides (such as NaOH) that were once known as alkalies.
The electron configurations of the alkali metals are characterized by a single valence electron. As a result, the chemistry of these elements is dominated by their tendency to lose an electron to form positively charged ions (Li+, Na+, K+).
| Li: | [He] 2s1 | Rb: | [Kr] 5s1 | ||
| Na: | [Ne] 3s1 | Cs: | [Xe] 6s1 | ||
| K: | [Ar] 4s1 | Fr: | [Rn] 7s1 |
The alkali metals lose electrons so easily that sodium dissolves in liquid ammonia at temperatures below the boiling point of ammonia (-33oC) to give Na+ ions and electrons.
| NH3(l) | |||
| Na(s) |  | Na+ | + e- |
The alkali metals react with the nonmetals in Group VIIA (F2, Cl2, Br2, I2, and At2) to form ionic compounds or salts.
Example: Chlorine reacts with sodium metal to produce sodium chloride, table salt.
2 Na(s) + Cl2(g) 2 NaCl(s)
Because they form salts with so many metals, the elements in Group VIIA are known as the halogens. This name comes from the Greek word for salt (hals) and the Greek word meaning "to produce" (gennan). The salts formed by the halogens are called halides. These salts include fluorides (LiF), chlorides (NaCl), bromides (KBr), and iodides (NaI).
The alkali metals react with hydrogen to form hydrides, such as potassium hydride, KH. They react with sulfur to form sulfides, such as sodium sulfide, Na2S. Although N2 is virtually inert to chemical reactions at room temperature, the most active metals react with nitrogen to form nitrides, such as lithium nitride, Li3N.
Elemental phosphorus reacts with the alkali metals to form phosphides, such as sodium phosphide, Na3P.