For example, to convert the mass of one lithium atom to the mass of \( \frac{6.941 \mathrm{amv}}{\mathrm{Li} \text { atom }} \times \frac{6.022 \times 10^{23} \mathrm{Li} \text { atoms }}{1 \mathrm{~mol}} \times \frac{1}{6.022 \times 10^{23}}=6.941 \frac{\mathrm{~g}}{\mathrm{~mol}} \mathrm{Li} \) atoms.

The idea behind this conversion is to show that the numerical value of an element’s atomic mass in atomic mass units (amu) is the same as its mass expressed in grams per mole (g/mol). Here’s how it works step by step: 1. A lithium atom has a mass of 6.941 amu. By definition, the atomic mass unit is set so that 1 amu is 1⁄12 the mass of a carbon-12 atom. 2. One mole of any substance contains Avogadro’s number (approximately 6.022×10²³) of atoms. Thus, one mole of lithium atoms has a total mass of:   (6.941 amu per atom) × (6.022×10²³ atoms per mole) 3. However, because 1 amu is defined such that when you have 6.022×10²³ amu (one mole of amu), it is equivalent to 1 gram per mole, we effectively have:   6.941 amu/atom × (1 g/mol per 1 amu) = 6.941 g/mol This is why multiplying by Avogadro's number and then dividing by the same number is a way to conceptually show that the number 6.941 amu per atom converts directly to 6.941 g/mol for a mole of lithium atoms.