Verified Answer :

The amount of
protons is equal to the number of electrons of a chemical element. The atomic
number of an element also determines the number of the protons it contains.
The number of protons is also the same number of electrons. Protons are positively charged, electrons are
negatively charged. To get the number of neutrons, all you need is to deduct
the number of  the atomic mass or mass number from the atomic number. Potassium has 19
protons, therefore has 19 electrons as well. The atomic mass of Potassium is

  1. So, the number of neutrons Potassium has is 20.

Potassium

Atomic
number: 19

Protons: 19

Electrons: 19

Atomic Mass:
39

Neutron: 20

Nitrogen

Atomic
number: 7

Protons: 7

Electrons: 7

Atomic Mass:
14.007

Neutrons: 7

Oxygen

Atomic
Number: 8

Protons: 8

Electrons: 8

Atomic Mass:
15.99

Neutrons: 8