Ionic Bond

The ionic bond occurs between metals and nonmetals. When a metal reacts with a nonmetal, the metal (as it has lower number of outermost shell electrons) loses/donatesits outermost shell electrons to the nonmetal. Thus it completes its outermost shell (octet), and forms a positively charged ion (cation), due to more protons than the total number of electrons.

The nonmetal, on the other hand, gains electrons to complete its outermost shell and forms a negatively charged ion (anion). Attraction between ions of these opposite charges results in the ionic bond.  

Properties of ionic compounds:

(i)  Composed of ions

(ii)  They are solids which are having high melting and boiling points

(iii)  Soluble in polar solvents like water but insoluble in non-polar solvents like alcohol, methylbenzene etc.

(iv)  Crystalline solids

(v)   Non-conductors of electricity in solid state but conducts electricity in aqueous or molten state.

(vi)  They are brittle.

(vii)  Chemical reactions involving ionic compounds are rapid.