Write answer to the following question and explain your answer.
Explain the need for a reference atom for atomic mass. Give some information about two reference atoms.
Mass of an atom is concentrated in its nucleus. It is th sum of proton(p) and neutron(n). The number(p+n) is called atomic mass number.
As we know that atom is very small in size, then how do we determine its mass? Therefore, the concept of reference atom for atomic mass is taken into consideration.
Initially hydrogen atom being lightest was chosen as the reference atom.The relative mass of hydrogen atom was accepted as (1). this is how relative atomic masses of various elements were determined in reference of hydrogen. For example: the mass of one nitrogen atom is fourteen(14) times that of a hydrogen atom.
Finally, the carbon was selected as reference atom. The relative mass of carbon atom was accepted as 12. The relative atomic mass of hydrogen compared to the carbon atom becomes 12 x 1/12 =1.