# Why do the alkali metals have to be stored under oil?

##### 1 Answer
Jan 5, 2017

Because they are highly sensitive to air-borne moisture and air.

## The oil acts as a barrier, or protective layer to air-borne moisture. When you cut a surface of the metal you see a shiny layer that tarnishes readily.

$N a \left(s\right) + {H}_{2} O \left(g\right) \rightarrow N a O H \left(s\right) + \frac{1}{2} {H}_{2} \left(g\right)$