Question

why electron spins around nucleus?

Answer 1

nucleus contains neutrons(neutral charges,having charge 0) and protons(positively charged particle) .electron are negatively charged particles that is outside nucleus,there is attraction between negatively & positively charged particles(protons & electrons).this force of attraction provides centripetal force between electrons and protons.As protons are heavier mass and bound by nuclear force with neutron inside nucleus,the light particle electron outside the nucleus revolves around the nucleus by virtue of centripetal force between it and proton.

Answer 2

Read about Heiseinberg's uncertainty principle. This would be a good place to start: http://plato.stanford.edu/entries/qt-uncertainty/

Answer 3

The weak nuclear force, one of the four fundamental forces in nature, is responsible for the attraction between the proton and the electron. The reason why the electron does not collide with the nucleus has to do with Heisenberg's uncertainty principle, which states that the more precisely you know a particle's position, the less precisely you can know its speed. Now, if an electron decelerates and thereby gets closer to the the atom, its position is thereby more accurately known, decreasing its speed limitations and allowing it to accelerate. The increase in speed lifts its orbit, providing a self-regulating concstant of speed.