An ion is a positively or negatively charged atom (or group of atoms).
Cations are positively charged species and are formed when a metal atom loses electrons.
Cations are represented by symbol of element and positive sign as superscript (A+).
Anions are negatively charged species and are formed when the atom of an element gains electrons.
Anions are represented by symbol of element and negative sign as superscript (A–).
The compounds which are made up of ions are known as ionic compounds.
In an ionic compound, the positively charged ions (cations) and negatively charged ions (anions) are held together by the strong electrostatic forces of attraction.
Sodium chloride Na+ + Cl– → NaCl
Formation of calcium chloride CaCl2
The force which hold the ions together in an ionic compound is known as ionic bond or electrovalent bond.
sodium chloride (NaCl) is an ionic compound.