Reaction of Metals with Oxygen :
When metals react with oxygen they form metal oxides, but the rate and intensity of reaction vary with different metals. For example, if the sodium metal is exposed to air it catches fire quickly hence it is stored in kerosene oil. As all the metals have different reactivity, so they combine with oxygen at different temperatures. Some of the common metals reacting with oxygen are as explained below.
Sodium metal reacts with oxygen of air at room temperature to form basic sodium oxide.
4Na + O2 (2Na2O)
(Sodium ) (Oxygen) → (Sodium oxide)
When you heat magnesium metal, it burns in the open air to give magnesium oxide.
2Mg + O2 → 2MgO
(Magnesium) (Oxygen) (Magnesium oxide)
Zinc metal is not very active as it burns in the air only when a strong heat is applied to form zinc oxide.
2Zn + O2 → 2ZnO
(Zinc) (Oxygen) (Zinc oxide)
Most of the metal oxides are not soluble in water, but some metal oxides gets easily dissolved in water to form metal hydroxides (or alkali). For example, oxides of sodium and potassium dissolve in water to form sodium hydroxide and potassium hydroxide respectively as follows.
Na2O + H2O → 2NaOH
(Sodium oxide ) (Water) (Sodium hydroxide )
K2O + H2O → 2KOH
(Potassium oxide) ( Water) ( Potassium hydroxide)
Sulphur reacts with oxygen to form acidic Sulphur dioxide.
S + O2 → SO2
(Sulphur) (oxygen ) (Sulphur Dioxide)