Ions

• An ion is a positively or negatively charged atom (or group of atoms).

Cations:

• 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⁺).

Sodium Cation:

Potassium Cation:

Magnesium Cation:

Calcium cation:

Anions:

• 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^–).

Example:

Ionic Compounds:

• 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.

For example:

• sodium chloride (NaCl) is an ionic compound.