An ordinary nickel contains about 10 24 electrons, all repelling one another. why don't these electrons fly off the nickel?

The question is


An ordinary nickel contains about 10²⁴ electrons, all repelling one another.why don't these electrons fly off the nickel?

You must know that to analyze the behaviour of the electrons in an atom, you must think in terms of quantum theory, not just electrostatic force.

Electrostatic considerations also is handled because the protons in the nucleus of an atoms have postive charge and they attract the electrons keeping the neutrality of the atom (same number of positive and negative charges in each atom).

Nevertheless, the "position" of the electrons in the atom is explained by the quantum theory in terms of levels of energy.

The electrons occupy orbitals (regions around the nucleus of the atom) following three rules:

1) The electrons will occupy the lower energetic level available. In principle they have these order (from lower energy to greater energy): 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p, with some variatons and exceptions.

2) Pauli's exclusion principle

At most two electrons may occupy one same atom orbital.

3) Hund's rule

Electrons with the same spin will occupy first all the orbitals with the same energy level. And this is precisely related with the repulsion force that two netatively charged particles exert on  each other.