Atomic Mass Formula

Atomic Mass Formula

The Atomic mass formula is a measure to find out the mass of one atom of an element. This article will enable the learners to compute the atomic mass of an atom of an element with conceptual clarity.

What is Atomic Mass?

Atomic mass is defined as the mass of the atoms that are present in any molecule or compound. The standard unit of atomic mass is kilogram while the non-standard unit of atomic mass is amu denoting atomic mass units. One amu is defined as one-twelfth of the mass of the C 12 carbon atom. Atomic mass can be calculated by the sum of the mass number of protons, electrons, and neutrons. We can determine the relative atomic mass of an atom also with the help of atomic mass. It is calculated by the average mass of the isotope of that element divided by the mass of the Carbon – 12 atom.

The Formula for Computing Atomic Mass 

Atomic mass can be calculated in three ways. 

• First, with the help of the periodic table, we can find out the atomic mass of any element. 
• Another way of calculating atomic mass is by the sum of the atomic mass of protons and neutrons. 
• Average atomic mass can also be calculated by the sum of the atomic mass of an isotope, multiplying each by the relative abundance of different isotopes of the element and dividing by the sum of the relative abundance of isotopes of the element.

Solved Examples

1. The atomic mass of an element that has the atomic number 22 and neutrons 24?  

The mass of neutrons is 24 and the mass of protons is equal to the atomic number of a given element, so it will be 22. 

The atomic mass of the element = Mass of protons + mass of neutrons

Atomic mass of the element = 24 + 22 = 46

Therefore, the atomic mass of the element that has the atomic number 22 and neutrons 24 is 46.

2. The atomic mass of an element that has the atomic number 36 and neutrons 32?  

The mass of neutrons is 32 and the mass of protons is equal to the atomic number of a given element, so it will be 36. 

The atomic mass of the element = Mass of protons + mass of neutrons

Atomic mass of the element = 36 + 32 = 68

Therefore, the atomic mass of the element that has the atomic number 36 and neutrons 32 is 68.