Convert moles, millimoles, micromoles, or nanomoles to atoms and back using the exact Avogadro constant, with optional atoms per particle.

Convert an amount of specified atoms, molecules or formula units to the total constituent atom count.

Use moles of atoms when atoms per particle is 1. For H₂O molecules, use 3 atoms per molecule. Zero is allowed.

Molecule or formula-unit options

Keep 1 for moles of atoms; use the total constituent atom count per specified molecule or formula unit.

Calculator Operations Required Inputs
Convert Moles to Atoms Number of Moles
Convert Atoms to Moles Total Number of Atoms

Moles to Atoms Formula

The following formula is used to convert the total moles to total atoms.

A = M × 6.02214076 × 10²³ × k
  • Where A is the number of atoms
  • M is the amount in moles of specified atoms, molecules or formula units; k is the number of constituent atoms per specified particle (1 for atoms)

Multiply the amount in moles by the exact Avogadro constant, 6.02214076 × 10^23 mol⁻¹, and by the atoms per specified particle. Use k = 1 for moles of atoms; for H₂O molecules, use k = 3. The SI mole definition requires the entity to be specified.

Moles to Atoms Conversion Table (moles of atoms; exact NA = 6.02214076 × 1023 mol−1)
Moles (mol) Atoms
0.0000016.02 × 1017
0.0016.02 × 1020
0.0053.01 × 1021
0.016.02 × 1021
0.021.20 × 1022
0.053.01 × 1022
0.16.02 × 1022
0.251.51 × 1023
0.53.01 × 1023
0.754.52 × 1023
16.02 × 1023
1.59.03 × 1023
21.20 × 1024
2.51.51 × 1024
31.81 × 1024
53.01 × 1024
7.54.52 × 1024
106.02 × 1024
251.51 × 1025
503.01 × 1025
* Rounded to 3 significant figures. Uses exact Avogadro constant NA = 6.02214076 × 1023 mol−1 and 1 atom per specified particle.

Moles to Atoms Definition

The mole (mol) is the SI unit of amount of substance. One mole contains exactly 6.02214076 × 10^23 specified entities. Multiplying moles of atoms by this constant gives atoms; multiplying moles of molecules gives molecules, then the constituent atom count requires the atoms-per-molecule factor.

Example Problem

How to calculate the number of atoms from moles?

First, determine the total number of moles in the substance. In general, this is done by multiplying the total number of moles per unit of volume by the total volume.

For this example, assume an amount concentration of 0.500 mol/L of H₂O molecules and a total solution volume of 3.00 L. Each H₂O molecule contains 3 constituent atoms.

Amount = concentration × volume = 0.500 mol/L × 3.00 L = 1.50 mol of H₂O molecules.

First calculate the number of H₂O molecules, then multiply by 3 to count their constituent atoms:

Number of molecules = M × 6.02214076 × 10^23 mol⁻¹.

Number of molecules = 1.50 × 6.02214076 × 10^23 = 9.03321114 × 10^23.

Total constituent atoms = 3 × 9.03321114 × 10^23 = 2.709963342 × 10^24, conventionally reported as 2.71 × 10^24 atoms for the three-significant-figure inputs. These atoms remain constituents of the molecules.

FAQ

What is a mole?

The mole (mol) is the SI unit of amount of substance. One mole contains exactly 6.02214076 × 10^23 specified elementary entities, such as atoms, molecules or formula units. The entity count is dimensionless; the amount of substance has unit mol.

How do you convert moles to grams?

Multiply the amount in moles by the molar mass in grams per mole: mass (g) = amount (mol) × molar mass (g/mol). Specify the substance and use its appropriate molar mass.