Isotope Notation — Overview & Examples

Isotope Notation

What Is An Isotope?

Before diving into isotope notation, here is a reminder on what an isotope is:

• Isotopes are atoms that have the same atomic number but different mass numbers due to the different number of neutrons they contain. There could be two or more isotopes that fall under the same atomic number.

• An example of an element that has isotopes is carbon. Carbon has three isotopes: C12 (containing 6 neutrons), C13 (containing 7 neutrons), and C14 (containing 8 neutrons)

What Is Isotope Notation?

• Isotope notation is used to visualize and discover what an isotope’s mass number is, as well as the number of neutrons, protons, and electrons an isotope contains

• Isotope notation contains: the mass number, atomic number, and charge (if there is one)

• Since isotopes have the same atomic number, it is also common to omit the atomic number from the isotope notation.

How to Find Number of Electrons, Protons, and Neutrons

• Finding the number of electrons, protons, and neutrons is simple when looking at isotope notation!

• Number of Protons: To find the number of protons, simply just look at the atomic number. The atomic number is also the number of protons in the atom!

• Number of Neutrons: To find the number of neutrons, simply subtract the atomic number from the mass number.

• Number of Electrons: The number of electrons is generally the same as the number of protons. The only exception is if there is a charge. A + charge means that there are more protons than electrons, so you must subtract the + charge amount from the atomic number to find the number of electrons. A - charge means there are more electrons than protons, so you must add the - charge amount to the atomic number to get the number of electrons!

Isotope Notation

(Video) Isotope Notation

By: Tyler DeWitt

This video does a great job at explaining and going over examples about Isotope Notation. It goes over how to figure out the number of neutrons, protons, and electrons are in an element from the notation, as well as gives a few examples to practice and perfect this skill.

You might be wondering why it is important to have a whole new way of displayed elements, but it is important to have a standardized way of presenting what form of an element we are using. A large part of the scientific method is communicating our results, meaning it is very important to identify what specific element is being studied to make our results reproducible.

Having a different number of protons and neutrons can lead to very different elemental functions. For example, some isotopes are very unstable and radioactive, like carbon-14. However, other isotopes that just differ by a few neutrons are not radioactive and are used all the time like carbon-12.