The **Avogadro constant** is a number used to explain atoms, molecules, ions, and electrons. It is named after the Italian scientist Amedeo Avogadro and is defined exactly as *N*A = 6.02214076×1023 mol−1. For elements, the relative atomic mass expressed in grams contains the Avogadro Constant of atoms. For instance, a mole of Carbon has exactly 6.022 x 1023 atoms of carbon, and if you weigh it, it would weigh 12.011 grams, carbon’s atomic weight.

## Boltzmann’s Constant

The fundamental constant of physics, the Boltzmann constant, is one of the seven "defining constants" that have been given exact definitions.