The group 1 elements are known as the Alkali metals because of their ability to form soluble hydroxides or alkalis according to the equations below. "X" represents the alkali metals, Li, Na, K, Rb, Cs and Fr.

Reactions with oxygen

 4X_(s) + O_2(g) => 2X₂O_(s)

 X₂O_(s) + H₂O_(l) => 2XOH_(s)

Reactions with water

2X_(s) + H₂O_(l) => 2XOH_(aq) + H_2(g)

The electronic configuration of these elements is as follows.
Li 1s², 2s¹

Na 1s², 2s², 2p⁶, 3s¹

K 1s², 2s², 2p⁶, 3s², 3p⁶, 4s¹

Rb 1s², 2s², 2p⁶, 3s², 3p⁶, 3d¹⁰, 4s², 4p⁶, 5s¹

Cs 1s², 2s², 2p⁶, 3s², 3p⁶, 3d¹⁰, 4s², 4p⁶, 4d¹⁰, 5s², 5p⁶, 6s¹

Notice how there is always one outer shell electron. All elements in group 1 have similar properties due to the similarity in their electronic configuration. The elements in group 1 show metallic properties. They are very soft and far too reactive to be used as structural material. Their reactivity increases as we go down the group and their oxidation state is always 1+. The 2+ oxidation state is never found for these elements as the second ionisation energy is very high.