Ionic Bonding

Main Content

What is Ionic Bonding?

Ionic bonding is the strong electrostatic attraction between oppositely charged ions in a crystal lattice.

Let's break this down:

• Electrostatic attraction means the force that pulls positive and negative charges together (like magnets attract)
• Ions are charged particles - they can be positive or negative
• A crystal lattice is a regular, repeating 3D pattern of ions (like a neat, organized structure)

Ionic bonding happens when a metal reacts with a non-metal. The metal loses electrons and the non-metal gains them, creating ions that attract each other strongly.

Cations (Positive Ions)

Cations are positively charged ions formed when metal atoms lose electrons.

Here's how it works:

• Metal atoms have 1, 2, or 3 electrons in their outer shell
• These outer electrons are relatively easy to remove
• When a metal atom loses its outer electrons, it becomes a cation (positive ion)
• The ion is smaller than the original atom
• The ion has a positive charge because it now has more protons than electrons

Example: Sodium (Na) has 1 electron in its outer shell. When it loses this electron, it becomes Na⁺ (a sodium cation).

The electronic configuration changes:

• Sodium atom (Na): 2,8,1
• Sodium ion (Na⁺): 2,8 (the outer electron is gone)

The energy needed to remove electrons from an atom is called the ionisation energy.

Anions (Negative Ions)

Anions are negatively charged ions formed when non-metal atoms gain electrons.

Here's how it works:

• Non-metal atoms have 5, 6, or 7 electrons in their outer shell
• They need just a few more electrons to complete their outer shell (to have 8 electrons, which is stable)
• When a non-metal atom gains electrons, it becomes an anion (negative ion)
• The ion is larger than the original atom
• The ion has a negative charge because it now has more electrons than protons

Example: Chlorine (Cl) has 7 electrons in its outer shell. When it gains 1 electron, it becomes Cl⁻ (a chloride anion).

The electronic configuration changes:

• Chlorine atom (Cl): 2,8,7
• Chloride ion (Cl⁻): 2,8,8 (gained 1 electron)

Energy is released when an atom gains an electron - this is called the electron affinity.