Question

How to find atomic mass of any element, explain.

Answer 1

Hint: Atomic mass is the mass of one atom of a given element. Unified atomic mass unit is the unit of the atomic mass and is given the symbol ‘u’. Atomic mass of an atom is equal to the total mass of all the electrons, protons and neutrons present in one atom.

Complete Step by step answer: The mass of an electron is negligible when compared to the mass of a proton or a neutron. Hence, you can say that the atomic mass is equal to the total mass of all the protons and neutrons present in the nucleus of an atom.
As we can observe that from a lot of experiments done for atomic models, it is evident that the most of the matter is concentrated at apoint in an atom, and we also know that the concentrated point is the nucleus and it contains the protons and neutrons only.
To obtain the atomic mass of a particular atom, you simply add the number of protons and the number of neutrons present in the atom. For example, consider an oxygen atom having 8 electrons, 8 protons and 8 neutrons. Simply add 8 protons and 8 neutrons to obtain the atomic mass of oxygen.
Thus, the atomic mass of oxygen is \[8 + 8 = 16\] .
The atomic mass of an element is also given in the periodic table. In the periodic table, the atomic mass is given in atomic mass units and in decimal figures.

Note: If an element contains two or more isotopes, then to obtain the average atomic mass of the element, you should know the atomic masses of individual isotopes and their relative abundances. For example, two isotopes of chlorine have atomic masses 35 and 37 with relative abundances of 3:1.
The average atomic mass of chlorine is \[\dfrac{{\left( {35 \times 3} \right) + \left( {37 \times 1} \right)}}{{3 + 1}} = 35.45\] .