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Atomic mass

Chemistry Formulas

Atomic Number or Proton Number (Z): 

The number of protons present in an atom is called the atomic number which is, denoted by Z. Hence, atomic number of an element = total number of protons present in an atom.

Z = no. of p+ = e-

Mass Number (A): Proposed after the discovery of neutron. 

The sum of the number of protons and neutrons (i.e. collectively known as nucleons) present in the nucleus of an element is called mass number and is denoted by A.  It is nearly equal to the atomic mass of that element.Hence, for an atom mass number = number of protons + number of neutrons.

A = p + n

or A = Z + n 

or n = A – Z

Difference between Mass Number and Atomic Mass:

A mass number is always a whole number whereas atomic mass is usually not a whole number because mass number is the sum of two integers so it can never be fractional, else we can say number of protons and neutrons can never be fractional. While atomic number is the average of atomic weights of all the isotopes of an element present in the nature. So it can be an integer or fractional value. For more chemistry Formulas visit formula section.

Find the list of Atomic Mass of Elements in the below Pdf

Atomic mass

Atomic mass

Atomic mass

Atomic mass

Atomic mass

Atomic mass

Atomic mass

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