Atom Calculator

The Building Blocks of the Universe

Everything you see, touch, and breathe is made of atoms. Despite their tiny size, atoms have an internal structure that determines the behavior of all matter. Understanding how to calculate the subatomic particles—protons, neutrons, and electrons—is the very first step in mastering chemistry.

Our Atom Calculator simplifies this process. By inputting just the Atomic Number and Mass Number (which you can find on any Periodic Table), you can instantly visualize the structure of any isotope or ion.

The Three Subatomic Particles

An atom is composed of three main particles. Knowing the charge and location of each is crucial.

How to Calculate Particles (APE MAN)

Chemistry students often use the mnemonic APE MAN to remember the math rules. Here is how to find the numbers manually.

1. Protons = Atomic Number (Z)

The identity of an element is defined solely by its number of protons.
If an atom has 6 protons, it is Carbon. If it gains a proton and has 7, it becomes Nitrogen.
Protons = Z

2. Electrons = Protons - Charge

In a neutral atom (charge is 0), the number of electrons equals the number of protons.
If the atom is an Ion (it has a charge), you must adjust the count.
Electrons = Protons - Charge

• Cation (+): Lost electrons (Subtract from protons).
• Anion (-): Gained electrons (Add to protons).

3. Neutrons = Mass Number - Atomic Number

The Mass Number (A) is the total count of particles in the nucleus (Protons + Neutrons). To find the neutrons, simply subtract the protons.
Neutrons = Mass (A) - Atomic (Z)

What is an Isotope?

You might notice that the mass on the Periodic Table is often a decimal (e.g., Carbon is 12.011). This is the average mass.

Individual atoms always have whole number masses. Atoms of the same element can have different numbers of neutrons. These are called Isotopes.

• Carbon-12: 6 Protons, 6 Neutrons. (Standard)
• Carbon-14: 6 Protons, 8 Neutrons. (Radioactive)

Our calculator asks for the specific Mass Number (A) so it can calculate the exact neutrons for that specific isotope.

What is an Ion?

Atoms "want" to be stable, which usually means having a full outer shell of electrons (like Noble Gases). To achieve this, they gain or lose electrons, becoming Ions.

• Metals (like Sodium): Tend to lose electrons, becoming Positive (+) Cations.
• Non-Metals (like Oxygen): Tend to gain electrons, becoming Negative (-) Anions.

Remember: You never change the number of protons to create a charge. Changing protons changes the element entirely (nuclear reaction). You only change electrons.