Introduction to Isotopes

Isotopes are atoms of the same element with different numbers of neutrons but the same number of protons. For example, different isotopes of the element Carbon can have 6, 7, or 8 neutrons. The number of protons does not change.

Isotopes of Carbon

Because of the different numbers of neutrons, isotopes also have different mass numbers.

Video: Introduction to Isotopes


Exercise: Select the isotopes of Oxygen below.
A B C
Oxygen as seen on the Periodic Table 7 protons
8 neutrons
Mass Number=15 		8 protons
8 neutrons
Mass # =16 		8 protons
10 neutrons
Mass # =18

Next Up: A = Z + N Calculations