Potassium, sodium, lithium and calcium: reactions with steam
If you were silly enough to try reacting potassium, sodium, lithium or calcium with steam, the resulting reaction would be so violent that the metal would explode, igniting the hydrogen in a fiery ball!
Metals below magnesium in the reactivity series will not react with water unless additional energy is supplied in the form of heat. This is done by heating the water until it turns to steam.
When metals react with steam, the resultants are a metal oxide and hydrogen. This is because the metal hydroxides, which would form with water, break up with heat (thermally decompose).