Question

What is the mass number of an atom which contains 28 protons, 28 electrons and 34 neutrons?

Answer 1

Hint: Elements in the periodic table are arranged in order of increasing atomic number. The sub atomic species in an atom are electrons, protons, and neutrons. The number of protons and electrons are equal which is equal to the atomic number. While the sum of protons and neutrons are the mass number.

Complete answer:
The structure of an atom consists of various sub – atomic species. The particles like electrons, protons, and neutrons are subatomic particles. Among them, electrons are negative species, protons are positive, while neutrons are neutral. The nucleus of an atom is the center of the atom that consists of a positive charge, while the electrons are present in various orbits.
The number of electrons and protons are equal in an atom which is the atomic number of an atom. The mass number of an atom is the sum of protons and neutrons. As the protons and neutrons are present in the nucleus, they are called nucleons. Therefore, the mass of an atom is centered in the nucleus.
We have been given an atom that has 28 protons, 28 electrons and 34 neutrons. So, the mass number will be the sum of protons and neutrons. This is,
Mass number = number of (protons + neutrons)
Mass number = 28 + 34
Mass number = 62
Hence, the mass number of the given atom is 62.

Note:
The mass number of any atom is represented in the unit of gram per mole. It is written as g/ mol or ‘u’ that denotes unified atomic mass units. So here the mass is 62 g/mol or 62 u. The number of moles in any atom is the particle which has the same unit for 1 mole of an atom that is Avogadro number, $6.022\times {10}^{23}$.