Discuss chemical properties of metals.

Chemical properties of metals are:

i) Reaction with dioxygen: Metal elements can easily donate electrons to dioxygen atom.

Metal elements combine with oxygen to form oxides.

Metal + Dioxygen → Metal oxides

e.g. 2Mg(s) + O₂(g) → 2MgO(s)

All metals do not react with dioxygen all metals show different properties such as metals like gold do not react with dioxygen at higher temperatures also.

ii) Reaction with water: Metals on reaction with water form hydroxides or oxides and produce dihydrogen gas. Metals such as sodium and potassium reacts vigorously with water and produce hydrogen gas.

Metal + Water → Metal hydroxide or Metal oxide + Dihydrogen gas

e.g. 2K(s) +2H₂O(l) → 2KOH(aq) + H₂(g)

Magnesium does not react with cold water but instead of it reacts with hot water to form magnesium hydroxide.

Mg(s) +2H₂O (l) → MgOH (aq) + H₂ (g)

Aluminium, zinc and iron metals do not reacts with hot or cold water but they react with water vapours to form oxides and hydrogen gas.

e.g. 2Al(s) +3H₂O (l) → Al₂O₃ (aq) + 3H₂ (g)

iii) Reaction with acid: All metals do not react with dilute acid. When metal reacts with dilute acid, salt of corresponding metal and di hydrogen gas is formed.

Metal + Dilute acid → Salt of corresponding metal + Dihydrogen gas

e.g. Mg(s) +H₂SO₄ (aq) → MgSO₄ (aq) + H₂ (g)

iv) Reaction with Dichlorine: Metals react with dichlorine to form metal chlorides.

Metal + Dichlorine gas → Metal chloride

e.g. Ca(s) + Cl₂(g) → CaCl₂(s)

v) Reaction with Dihydrogen: All metals do not react with dihydrogen because metals donate electrons and dihydrogen does not accept electron.

Metals such as Na, K, Ca combine with hydrogen and form hydrides of that metal.

Active metal + Dihydrogen gas → Metal hydride

e.g. Ca(s) + H₂(g) → CaH₂(s)