Alkali metal

The elements in Group 1 are called the alkali metals. Lithium, sodium, potassium, rubidium and caesium are examples. Because they are metals, we might expect them to resemble familiar metals such as iron, but two of their physical properties are unusual: they are soft and have relatively low melting points.

Group 1 contains the alkali metals, including lithium, sodium and potassium. They are metals, but they are unusual compared with many familiar metals: they are soft enough to cut, have relatively low melting points and have low densities. Lithium, sodium and potassium are less dense than water, so they float.