When two elements react together to form ions, the resulting cations and anions, which have opposite electrical charges, attract each other. They stay together because of this attraction. This type of bonding is known as ionic bonding and the electrostatic bonds are called ionic bonds. Elements far apart in the periodic table tend to exhibit this kind of bonding, coming together to form ionic compounds. 

IONIC COMPOUND  is a compound whose components are held together by ionic bonding. It has no molecules, instead the cations and anions attract each other to form a giant ionic lattice.

PROPERTIES OF IONIC COMPOUNDS:

• They have high melting and boiling points (the bonds are strong and hence large amounts of energy are needed to break them).

• They dissolve in water.

• They conduct electricity when molten or in aqueous solution because they contain charged particles (ions) which are free to move.