Question

What kind of atom has the same number of $p +$ and ${e^ - }$?

Answer 1

Michael Faraday was the first one to show that if electricity is passed through a solution of an electrolyte, chemical reactions occur at the electrodes. This suggested the particulate nature of electricity.

Complete answer:
Before the discovery of subatomic particles, people believed that atoms are the smallest unit of matter but after performing his cathode ray experiment, particulate nature of electricity was discovered and in the cathode ray tube there were rays going from the anode side to the cathode side. These rays were negatively charged and therefore they were named electrons.
What we knew after this is that the atom has to be neutral because the matter is never charged then there must be something to balance the charge. Protons were discovered by Chadwick, when he experimented with modified cathode ray tubes which produced canal rays which went from the cathode side to the anode side and therefore there were some positively charged particles.
Many atomic models came after that to propose what the charges were on one proton and one electron, which came to be the same according to Millikan's oil drop experiment.
The protons were to be found in the nucleus of an atom which also has neutrons and tes can’t exit the nucleus while the electrons revolve around the nucleus due to electronegative centrifugal force.
Therefore, for the atom to be stable, there has to be the same and equal number of protons and electrons.
All atoms have the same number of $p +$ and ${e^ - }$.

Note:
Rutherford’s model was the first model which gave the fair idea regarding the orientation of electrons and protons in an atom. Nucleus is at its centre and very small, while the revolving electrons occupy the empty space.