Relative Atomic Mass and Relative Molecular Mass (1)

Method of calculation of the relative molecular mass of a molecule

Adding up the relative atomic masses of all the atoms that form the molecule

The definition of the relative atomic mass, RAM of an element

The average mass of an atom of the element compared to 1/12 of the mass of one carbon-12 atom

The definition of the relative molecular mass, RMM of a molecule

The average mass of the molecule compared to 1/12 of the mass of one carbon-12 atom

Formulae for relative atomic mass of an element

Formulae for relative molecular mass of a substance

Concept of Relative Atomic Mass, RAM (1)

Chemists use the concept of ‘relative atomic mass’ by comparing the mass of atom of an element to the mass of atom of another element that is chosen as the standard

Concept of Relative Atomic Mass, RAM (2)

Therefore, we do not need to know the actual mass of an atom

Concept of Relative Atomic Mass, RAM (3)

Initially, the hydrogen atom was used as the standard atom because it is the lightest atom

Concept of Relative Atomic Mass, RAM (4)

Masses of atoms of all other elements were compared with the hydrogen atom

Concept of Relative Atomic Mass, RAM (5)

For example, one carbon atom is as heavy as 12 hydrogen atoms

Chemistry

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Relative Atomic Mass and Relative Molecular Mass (1)

Relative Atomic Mass and Relative Molecular Mass (1)