How to find mass number

How to Find the Number of Protons, Neutrons, and Electrons. Step by Step Explanation with Examples

In this post, we’ll be going over how to determine the number of protons, neutrons, and electrons in an atom or ion.

Elements protons, neutrons, and electrons list

We’ll first start by discussing what each of the components in the nuclide notation means. Then we’ll go through two examples together.

The Nuclide Notation

The letter(s) in the middle is the symbol of the element.

The number on the bottom left corner is the atomic number, which tells you the number of protons.

The number on the upper left corner is the mass number, which is equal to the neutrons and protons added together.

Lastly, the charge is on the upper right corner.

If there isn’t any number or signs, then it means that atom has no charge and is neutral.

Rules to Finding Number of Protons, Neutrons, and Electrons

# of protons = atomic number

# of neutrons = mass number – atomic number

# of electrons = atomic number – charge

That’s it!

Examples

Great, lets apply the rules to some examples.

how to find neutrons in an element using periodic table

how to find neutrons in an element with a charge