Question

Why is the nucleus positively charged ?

Answer 1

An atom as a whole is a neutral particle.It consists of two parts: the nucleus and electrons . A nucleus is spherical in shape and is surrounded symmetrically by electron clouds . We know that electrons are negatively charged and the atom as a whole is neutral therefore there must be some positive entity .

Complete step by step answer:
Nucleus of an atom is very heavy and it consists of almost $99\%$ mass of total atoms because the mass of the electron is negligible.Nucleus contains two subatomic particles known as protons and neutrons . Neutrons and protons are collectively called nucleons .
Neutrons are electrically neutral particles and it is the proton due to which the nucleus is positively charged because protons have positive charge .The number of protons in the nucleus is the same as the number of electrons and of the same magnitude hence making the atom electrically neutral. Mass of the proton is slightly less than that of the neutron and the magnitude of charge on one proton is represented as $+ 1e$ (magnitude of charge on one electron) .
Note:
Protons inside the nucleus being positively charged attract negatively charged electrons and due to this attraction electrons revolve around the nucleus in its orbit .
The number of neutrons in a nucleus decides which chemical element it is , in other words we can easily predict the chemical element just by knowing the number of protons.The number of protons in an element also is also known as its atomic number .