Atom Calculator
Calculate the number of protons, neutrons, and electrons in any atom or ion using atomic number, mass number, and charge. Free online chemistry calculator with element identification, particle breakdowns, and interactive charts.
About This Calculator
The Atom Calculator helps students, teachers, and researchers quickly determine the composition of any atom or ion. Simply enter the atomic number (Z), mass number (A), and charge (z) to instantly find the number of protons, neutrons, and electrons, along with the element's name and symbol from the periodic table.
The calculator applies the fundamental atomic structure formulas: protons = atomic number (Z), neutrons = mass number (A) - atomic number (Z), and electrons = atomic number (Z) - charge (z). For neutral atoms the charge is zero, resulting in equal numbers of protons and electrons. The element is identified by looking up the atomic number in the periodic table, covering all 118 confirmed elements from hydrogen (Z=1) to oganesson (Z=118).
This tool is essential for understanding atomic structure, studying isotopes (same Z, different A), working with ions (charged atoms), and solving general chemistry problems. It supports all naturally occurring and synthetic elements, including all common isotopes such as carbon-12, carbon-13, carbon-14, uranium-235, and uranium-238. The calculator also identifies whether the atom is neutral, a cation (positive charge), or an anion (negative charge) based on the proton-electron balance.
Frequently Asked Questions
What is an atom?
An atom is the smallest constituent unit of matter that retains the properties of an element. It consists of a nucleus containing protons and neutrons, surrounded by electrons in orbitals.
How do I calculate the number of protons, neutrons, and electrons in an atom?
Enter the atomic number (Z), mass number (A), and charge (z). The calculator computes protons = Z, neutrons = A - Z, and electrons = Z - z. For neutral atoms, charge is 0.
What is the difference between atomic number and mass number?
The atomic number (Z) is the number of protons in the nucleus, which identifies the element. The mass number (A) is the total number of protons and neutrons in the nucleus.
What is an ion?
An ion is an atom with an unequal number of protons and electrons, giving it a net electrical charge. Cations have more protons than electrons (positive charge), while anions have more electrons than protons (negative charge).
What are isotopes?
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. For example, carbon-12 has 6 neutrons while carbon-14 has 8 neutrons, but both have 6 protons.
How does the atom calculator identify elements?
The calculator looks up the element by its atomic number (Z) using the periodic table. Each element has a unique atomic number — hydrogen is 1, helium is 2, carbon is 6, and so on up to oganesson at 118.
Can I use this calculator for chemistry homework?
Yes, this calculator is designed for students and researchers to quickly find the atomic composition of any element or ion by entering the atomic number, mass number, and charge.
What happens if I enter an atomic number greater than 118?
The periodic table currently has 118 confirmed elements. Entering an atomic number above 118 will show Unknown as the element name since no such element has been discovered or confirmed.