Calculation of Number of Sub-Atomic Particles

An atom consists of a nucleus surrounded by electrons.

The nucleus consists of protons and neutrons.

The number of protons in an atom determines its atomic number.

Atoms of different elements have a different number of protons, thus different atomic numbers.

The total number of protons and neutrons in the nucleus of the atom is called mass number.

Atoms of an element have the same atomic number, but the mass number may vary.

An atom contains equal number of protons and electrons.

Since electrons and protons have equal and opposite charges, this makes an atom electrically neutral.

To calculate the subatomic particles we can use the atomic number and mass number of an atom.

Let us calculate the number of the subatomic particles if the atomic number of the atom is 11 and the mass number is 23.

The number of electrons in an atom may change depending on the charge on the atom.

In a neutral atom, the number of electrons is exactly equal to its atomic number.

Electrons can be removed or added to an atom without changing its identity.

The resulting species are charged also known as ions.

The number of electrons in a positively charged species is less than the number of protons in the nucleus.

The number of electrons in a negatively charged species is more than the number of protons in the nucleus.

Let us find the number of subatomic particles in sodium and chloride ions.

Revision

Electrons, protons and neutrons are the subatomic particles in an atom.

The number of electrons in a positively charged species is less than the number of protons in the nucleus.

The number of electrons in a negatively charged species is more than the number of protons in the nucleus.

The end