Mole Definition in Chemistry

different sized weights

 artpartner-images, Getty Images

A Mole is defined as a chemical unit, defined to be 6.022 x 1023 (Avogadro's Constant) entities. In science, this is usually molecules or atoms. The mass of a mole is the gram formula mass of a substance.

Examples:

  • 1 mole of NH3 has 6.022 x 1023 molecules and weighs about 17 grams (Nitrogen's molecular weight is 14 and Hydrogen is 1, 14 + 3 = 17).
  • 1 mole of copper has 6.022 x 1023 atoms and weighs about 63.54 grams.