Mole Definition

A mole is a unit of mass.
artpartner-images, Getty Images
by
Anne Marie Helmenstine, Ph.D.
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
Updated March 08, 2017

Mole Definition: a chemical mass unit, defined to be 6.022 x 1023molecules, atoms, or some other unit. The mass of a mole is the gram formula mass of a substance.

Examples: 1 mole of NH3 has 6.022 x 1023molecules and weighs about 17 grams. 1 mole of copper has 6.022 x 1023atoms and weighs about 63.54 grams.