Valency is the measure of an element's ability to combine with other elements, determined by the number of electrons that can be gained, lost, or shared in the formation of chemical bonds. Here’s how to determine the valency of iron, aluminum, and sulfur:
1. Iron (Fe)
Iron can exhibit more than one valency:
- Common oxidation states: +2 (ferrous) and +3 (ferric).
- The valency is often determined by the electrons in the outer shell: Iron has an atomic number of 26, with the electron configuration of [Ar] 4s² 3d⁶. It can lose 2 electrons from the 4s subshell (valency +2) or lose a total of 3 electrons (2 from 4s and 1 from 3d subshell) to achieve a +3 oxidation state.
Valency of iron: +2 or +3.
2. Aluminum (Al)
- Common oxidation state: +3.
- Aluminum has an atomic number of 13 with the electron configuration of [Ne] 3s² 3p¹. It has three electrons in its outer shell (the 3s and 3p subshells), which it tends to lose to achieve a stable electron configuration similar to that of neon.
Valency of aluminum: +3.
3. Sulfur (S)
- Common oxidation states: -2, +4, and +6.
- Sulfur has an atomic number of 16 and an electron configuration of [Ne] 3s² 3p⁴. It can gain 2 electrons to complete its outer shell (achieving a -2 oxidation state) or lose 6 electrons from its outer shell to achieve +6 (in compounds like sulfuric acid, H₂SO₄).
Valency of sulfur: -2, +4, or +6.
Summary:
- Iron (Fe): Valency of +2 or +3.
- Aluminum (Al): Valency of +3.
- Sulfur (S): Valency of -2, +4, or +6.