Avogadro’s Number Definition

The number of atoms, molecules, formula units or ions in one gram atom, one gram molecule, one gram formula unit or one gram ion, respectively is called Avogadro’s number.

OR

The number of atoms, molecules, formula units or ions in one mole of the substance is called Avogadro’s number.

Representation of Avogadro’s Number:

It is represented by N_A.

Value of Avogadro’s Number:

Its value is 6.02 x 10²³.

Examples:

• 1 gram of H = 1 gram atom of H = 1 mole of H = 6.02 x 10²³ atoms of H

• 2 grams of H₂ = 1 gram molecule of H₂= 1 mole of H₂ = 6.02 x 10²³ molecules of H₂

• 58.5 grams of NaCl = 1 gram formula mass of NaCl= 1 mole of NaCl = 6.02 x 10²³ formula units of NaCl

• 23 grams of Na⁺¹= 1 gram ion of Na⁺¹ = 1 mole of Na⁺¹ = 6.02 x 10²³ ions of Na⁺¹

Formulas, which can be used to calculate the number of atoms, molecules, formula units or ions in the given sample of a substance are given below:

Also Read: Avogadro’s Law