Question

When the number of protons and electrons possessed by an atom are unequal, the atom __________?

Answer 1

Answer : When the number of protons and electrons possessed by an atom are unequal, the atom is charged.

Explanation :

Atomic number is defined as the number of protons or electrons that are present in a neutral atom.

Atomic number = number of protons = number of electrons

For the neutral atom, the number of protons and electrons are equal. But, they are unequal when the atoms present in the form of ions or the atom has some charge.

An ion is formed when an atom looses or gains electron.

When an atom looses electrons, it will form a positive ion known as cation.

When an atom gains electrons, it will form a negative ion known as anion.

For example : The neutral atom Na has equal number of protons and electrons i.e 11 but
`Na^+` ion has unequal number of protons and electrons that means it has 11 number of protons and 10 number of electrons.

Hence, when the number of protons and electrons possessed by an atom are unequal, the atom is charged.

Answer 2

The protons in an nucleus of an atom will not change unless a nuclear reaction takes place. The number of protons is equal to the atomic number of the element. For a neutral atom, the number of electrons and protons are equal. When they are unequal, then the atom occurs as an ion. It will has a net charge with it. For example, ion Ca²⁺ has a net charge of positive 2 because it has 2 more protons than its electrons.