Formation of Ions

Ion

Charged particle formed by gaining or losing electrons

Cation

Positive ion formed by losing electrons

Anion

Negative ion formed by gaining electrons

Metals form ions by

Losing electrons

Non‑metals form ions by

Gaining electrons

Group 1 metals

Lose 1 electron → form +1 ions

Group 2 metals

Lose 2 electrons → form +2 ions

Group 3 metals

Lose 3 electrons → form +3 ions

Group 5 non‑metals

Gain 3 electrons → form –3 ions

Group 6 non‑metals

Gain 2 electrons → form –2 ions

Group 7 halogens

Gain 1 electron → form –1 ions

Reason metals lose electrons

To achieve full outer shell (noble gas configuration)

Reason non‑metals gain electrons

To achieve full outer shell

Electron loss effect

Ion becomes positively charged

Electron gain effect

Ion becomes negatively charged

Example: sodium

Na → Na⁺ + e⁻

Example: magnesium

Mg → Mg²⁺ + 2e⁻

Example: chlorine

Cl + e⁻ → Cl⁻

Example: oxygen

O + 2e⁻ → O²⁻

Ionic charge depends on

Number of electrons lost or gained

Dot‑and‑cross diagrams

Show electron transfer between atoms

Ions have full outer shells

Makes them stable