METALS REACTION WITH AIR:-
Metals react with air to form metal oxides
Metal + Oxygen → Metal Oxide
4Fe + 3O2 → 2Fe2O3
Iron reacts with oxygen to form iron oxide commonly known as Rust
2Cu + O2 → 2CuO
when copper is heated in air, it combines with oxygen to form copper(II) oxide, a black oxide.
Metals such as potassium and sodium react so vigorously that they catch fire if kept in the open. Hence, to protect them and to prevent accidental fires, they are kept immersed in kerosene oil.
Silver and gold do not react with oxygen even at high temperatures.