# What is Relative atomic mass definition?

“The mass of one atom of an element compared with the mass of one atom of carbon taken as 12 is called relative atomic mass of the element.”

### Explanation:

The mass of one atom of magnesium is two times the mass of one atom of carbon, therefore relative atomic mass of magnesium would be 24.

## Atomic Mass Unit:

The relative atomic mass is expressed in atomic mass unit (amu). It is the 1/12th of the mass of one atom of 12C.

The relative atomic mass of C is 12.0000 amu whereas that of H is 1.008.

The masses of the atoms vary from 10-24 to 10-23 grams. Since such an extremely small mass cannot be measured by any balance, this is why relative atomic masses are used.

The relative atomic mass of some important elements are as follows:

Relative Atomic Mass of Hydrogen:  1.008 amu

Relative Atomic Mass of Carbon:   12.0000 amu

Relative Atomic Mass of Oxygen:  15.9994 amu

Relative Atomic Mass of Cupper:   63.546 amu

Relative Atomic Mass of Cesium:   132.905429 amu

Relative Atomic Mass of Uranium:   238.0289 amu

Relative Atomic Mass of Neon:   20.1797 amu

Relative Atomic Mass of Chlorine:    35.453 amu