Define valency by taking examples of silicon and oxygen.
- Valency is the combining capacity of an atom.
- Atomic number = 14
- Number of electrons = Atomic number = 14
- Electronic configuration of silicon is 2,8,4
- Hence, the valence shell has 4 e -
- It has equal chance of gaining, losing or sharing it's valence electrons in order to achieve octet
- In any case the valency of silicon = 4
- Atomic number = 8
- Number of electrons = Atomic number = 8
- Electronic configuration of Oxygen is 2,6
- Hence, the valence shell has 6 e -
- If an atom has 6 electrons in its valence shell, it is easier for them to gain 2 e- to achieve an octet
- Therefore, valency of oxygen = 2