Introduction to Isotopes and Definition

The definition for isotopes is that they are atoms of the same element with different numbers of neutrons. In this video we’ll look at the isotopes of Carbon (C) to understand how isotopes of the same element differ, how we name isotopes, and the effect of adding additional neutrons to an atom.

A core concept is that isotopes are the result of a different number of neutrons for an element. For example, Carbon has atomic number six. This means all Carbon atoms have six protons.
However, the number of neutrons can vary for different atoms of Carbon. While most atoms have six neutrons, Carbon atoms with seven neutrons are still stable. Only when we have eight neutrons does Carbon become unstable. Unstable atoms can undergo nuclear decay and emit radiation.

A few big ideas:

the number of neutrons doesn’t always equal the number of protons in stable isotopes.

not all isotopes are radioactive.

there is not “standard” or “original” isotope. Carbon-12 and Carbon-13 are both isotopes of Carbon.

in general, isotopes have the very similar chemical and physical properties.

isotopes are not listed on the Periodic Table.

For more information on isotopes visit terpconnect.umd.edu/~wbreslyn/chemistry/isotopes/ .