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How to find the valency of iron?

Published in Chemical Valency 2 mins read

The valency of iron can be determined by examining how it uses its valence electrons to form chemical bonds. Iron's valency isn't fixed; it commonly exhibits multiple valencies.

Understanding Iron's Valence Electrons

  • As highlighted in the YouTube video "Valence Electrons for Fe (Iron)," determining the valence electrons is key to understanding iron's bonding behavior. We need to consider the electrons outside the noble gas core.

Common Valencies of Iron

Iron commonly exhibits two valencies:

  • +2 (Ferrous state): Iron loses two electrons.
  • +3 (Ferric state): Iron loses three electrons.

Determining Valency in a Compound

To find the valency of iron in a specific compound:

  1. Identify the other elements: Determine the elements bonded to iron.
  2. Determine their valencies: Know the common valencies of these elements.
  3. Use the principle of charge neutrality: The sum of the positive and negative charges in a neutral compound must equal zero.

Examples

Here are a few examples to illustrate how to determine the valency of iron:

  • Iron(II) Oxide (FeO): Oxygen typically has a valency of -2. Therefore, iron must have a valency of +2 to balance the charge.

  • Iron(III) Oxide (Fe₂O₃): Each oxygen has a valency of -2, and there are three oxygen atoms, totaling -6. To balance this, the two iron atoms must have a total valency of +6. Therefore, each iron atom has a valency of +3.

  • Iron(II) Chloride (FeCl₂): Chlorine typically has a valency of -1. With two chlorine atoms, the total negative charge is -2. Thus, iron has a valency of +2.

  • Iron(III) Chloride (FeCl₃): With three chlorine atoms, the total negative charge is -3. Therefore, iron has a valency of +3.

Summary

In summary, to find the valency of iron in a compound, identify the other elements present, determine their valencies, and use the principle of charge neutrality to deduce the valency of iron. Remember iron commonly exists in +2 and +3 states by utilizing its valence electrons for chemical bonds.