Question

negative negative repel each other then how the electrons limit in same atom

Answer 1

Electrons in atoms are placed in zones called ‘orbitals’. In each orbital there is a limit of the number of electrons because electrons are a type of particle called ‘fermion’ which can’t share the same quantum properties. (No-one knows why this is - it’s just the observed behaviour). In some atoms there are orbitals which don’t have all the electrons that could fit. An example is hydrogen. In hydrogen the orbital could fit two electrons, but hydrogen only has one electron.

Because there is space for more electrons, electrons from other atoms can temporarily enter that orbital. For example, if there are two hydrogen atoms, their single electrons can swap back and forth between the orbitals in both atoms.

If you work out the quantum mechanics of two hydrogen atoms with their electrons swapping back and forth, you can find that the overall energy varies depending on how far apart the hydrogen atoms are. The energy is the sum of many things - the repulsion of electrons, the repulsion of the nuclei, and the attraction of electrons and nuclei. Feed all these things in, and you will find that there is a distance at which the energy is lowest. At this distance, the two hydrogen atoms are so close we call them a hydrogen molecule. If you try and move the hydrogen atoms more together or further apart you will need to add energy. This change in energy with distance has a name - it’s called ‘force’.

Atoms which bond this way are said to have ‘covalent’ bonds. The bond isn’t due directly to electrostatic interactions - it’s a quantum-mechanical thing - the sharing of electrons between atoms results in a lowering of energy

Answer 2

negative electrons are placed in an orbit.
As per my thinking the positive electrons at the centre attract the -ve electrons to make them stable