Example #1: 0.450 mole of Fe contains how many atoms?

Number of Fe atoms = 2.709 × 10^23 atoms.

Explanation:

Given the following data;

Number of Fe moles = 0.450 mole

We know that Avogadro constant is equal to 6.02 * 10^23 mol¯¹

Number of Fe atoms = number of Fe moles * Avogadro constant

Substituting into the equation, we have;

Number of Fe atoms = 0.450 × 6.02 * 10^23

Number of Fe atoms = 2.71 × 10^23 atoms.

Note: Fe is the symbol for the chemical element Iron.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8