Metals react with water and produce a metal oxide and hydrogen gas. Metal oxides that are soluble in water dissolve in it to further form metal hydroxide. But all metals do not react with water.
Metal + Water → Metal oxide + Hydrogen Metal oxide + Water → Metal hydroxide
Metals like potassium and sodium react violently with cold water. In case of sodium and potassium, the reaction is so violent and exothermic that the evolved hydrogen immediately catches fire.
2K(s) + 2H2O(l) → 2KOH(aq) + H2 (g) + heat energy 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2 (g) + heat energy
The reaction of calcium with water is less violent. The heat evolved is not sufficient for the hydrogen to catch fire.
Ca(s) + 2H2O(l) → Ca(OH)2 (aq) + H2 (g)