Atom Calculator
Compute atom using validated scientific equations. See step-by-step derivations, unit analysis, and reference values. Get results you can export or share.
Reviewed by Manoj Kumar, Mathematics Educator
Formula
Neutrons = A - Z | Electrons = Z - charge | Atoms = moles * 6.022e23
The atomic number Z gives the number of protons. Neutrons equal mass number minus atomic number. Electrons equal protons minus charge. Total atoms from moles uses Avogadro number.
Worked Examples
Example 1: Carbon-12 Atom
Problem:Determine subatomic particles for Carbon-12 (Z=6, A=12, neutral)
Solution:Protons = Z = 6\nNeutrons = A - Z = 12 - 6 = 6\nElectrons = Z - charge = 6 - 0 = 6\nConfig: 1s2 2s2 2p2
Result:6 protons, 6 neutrons, 6 electrons
Example 2: Iron-56 with 2 Moles
Problem:Calculate properties of 2 moles of Fe-56 (Z=26, A=56)
Solution:Protons = 26, Neutrons = 30, Electrons = 26\nAtoms = 2 * 6.022e23 = 1.204e24\nTotal mass = 2 * 56 = 112 g
Result:26p, 30n, 26e | 1.204e24 atoms | 112 g
Frequently Asked Questions
What are the subatomic particles in an atom?
An atom consists of three types of subatomic particles: protons, neutrons, and electrons. Protons carry a positive charge (+1) and are found in the nucleus, with the number of protons defining the element (atomic number Z). Neutrons have no charge and also reside in the nucleus, contributing to atomic mass and nuclear stability. Electrons carry a negative charge (-1) and orbit the nucleus in probability clouds called orbitals. In a neutral atom, the number of electrons equals the number of protons.
How do you determine the number of neutrons in an atom?
The number of neutrons is calculated by subtracting the atomic number (Z) from the mass number (A): Neutrons = A - Z. The atomic number is the number of protons and defines the element, while the mass number is the total number of protons plus neutrons. For example, Carbon-14 has Z=6 and A=14, so it has 14-6=8 neutrons, while regular Carbon-12 has only 6 neutrons. Isotopes of the same element have the same number of protons but different numbers of neutrons.
What is the role of Avogadro number in atom calculations?
Avogadro number (6.02214076 x 10^23) defines the number of atoms, molecules, or particles in one mole of a substance. It bridges the macroscopic world (grams, liters) with the atomic world (individual atoms and molecules). To find the number of atoms in a sample, multiply the number of moles by Avogadro number. To find the mass of a single atom, divide the molar mass by Avogadro number. For example, one mole of carbon (12 g) contains 6.022 x 10^23 carbon atoms, and each atom has a mass of 1.994 x 10^-23 g.
References
Reviewed by Manoj Kumar, Mathematics Educator · Editorial policy