Valency
Valency is the combining capacity of an atom. It determines how many electrons an atom can lose, gain, or share to achieve a stable electronic configuration (usually noble gas configuration).
Calculation of Valency Using Electronic Configuration
For elements with 1 to 4 valence electrons → Valency = Number of valence electrons
For elements with 5 to 8 valence electrons → Valency = 8 – Number of valence electrons
Examples of Valency Calculation
| Element | Symbol | Atomic Number | Electronic Configuration | Valence Electrons | Valency |
|---|---|---|---|---|---|
| Sodium | Na | 11 | 2,8,1 | 1 | 1 |
| Magnesium | Mg | 12 | 2,8,2 | 2 | 2 |
| Oxygen | O | 8 | 2,6 | 6 | 8-6 = 2 |
| Chlorine | Cl | 17 | 2,8,7 | 7 | 8-7 = 1 |
| Carbon | C | 6 | 2,4 | 4 | 4 |
| Nitrogen | N | 7 | 2,5 | 5 | 8-5 = 3 |
Diagram: Valency Determination for Common Elements (Na, Cl, O, Mg, etc.)
(A visual diagram showing electron distribution in shells and how elements gain/lose/share electrons to achieve a stable configuration.)
Valency helps in understanding chemical bonding, whether an element will form ionic or covalent bonds in compounds.