Question

Define valency by taking examples of silicon and oxygen.

Answer 1

The valency of an element is the combining capacity of that element. The valency of an element is determined by the number of valence electrons present in the atom of that element.

Valency of Silicon: It has electronic configuration: 2,8,4. Thus, the valency of silicon is 4 as these electrons can be shared with others to complete octet.

Valency of Oxygen: It has electronic configuration: 2,6. Thus, the valency of oxygen is 2 as it will gain 2 electrons to complete its octet.

Answer 2

Definition of Valency

Valency:
Valency is the combining capacity of an element, which determines how many atoms of another element it can bond with to form a stable chemical compound. Valency is typically determined by the number of electrons in the outermost shell (valence shell) of an atom that can participate in forming chemical bonds.

Valency of Silicon (Si)

Silicon (Si):
- Atomic Number: 14
- Electronic Configuration: \(1s^2 2s^2 2p^6 3s^2 3p^2\)

Determining Valency:
- Silicon has 4 electrons in its outermost shell (3s^2 3p^2).
- To achieve a stable configuration (similar to the nearest noble gas, argon), silicon can either gain 4 electrons or lose 4 electrons. However, silicon typically shares these 4 electrons to form covalent bonds.
- Therefore, the valency of silicon is 4.

Example:
- Compound Formation: In silicon dioxide (SiO\(_2\)), each silicon atom forms four covalent bonds with two oxygen atoms, where each oxygen atom shares two electrons with silicon. Valency of Oxygen (O)

Oxygen (O):
- Atomic Number: 8
- Electronic Configuration: \(1s^2 2s^2 2p^4\)

Determining Valency:
- Oxygen has 6 electrons in its outermost shell (2s^2 2p^4).
- To achieve a stable configuration (similar to the nearest noble gas, neon), oxygen needs to gain 2 electrons.
- Therefore, the valency of oxygen is 2.

Example:
- Compound Formation: In water (H\(_2\)O), each oxygen atom forms two covalent bonds with two hydrogen atoms, where each hydrogen atom shares one electron with oxygen.

Summary

- Silicon (Si):
 - Valency: 4
 - Example Compound: Silicon Dioxide (SiO\(_2\))
 - Silicon forms four covalent bonds by sharing its four valence electrons.

- Oxygen (O):
 - Valency: 2
 - Example Compound: Water (H\(_2\)O)
 - Oxygen forms two covalent bonds by gaining two electrons to achieve a stable configuration.

Valency is a fundamental concept that explains how atoms of different elements combine to form compounds, thereby achieving stable electronic configurations.