Question

why elecytrons revolving around the nucleus?

Answer 1

well , still this question is a difficult one to answer but we know that electron is negatively charged particle and nucleus is positively charge particle and they have electro static interaction to rotate electron around the nucleus .

Answer 2

having an equal number of protons (+ charge particle of an atom) to the number of electrons (- charge particle of an atom) makes the resultant force acting between them makes the electrons steady in its orbit plus the effect of centripetal force that makes the electron just continuously rotating around the nucleus of the atom...