A sphere of positive charge, with negatively charged electrons imbedded inside it
Due to the Strong Nuclear Force that balances repulsion and holds the nucleus together
Because elements are in their simplest chemical form
The total number of protons and neutrons in the nucleus
Atoms of the same element that have different number of neutrons but have the same amount of protons
6 protons and 8 neutrons
They all have the same number of electrons in their outer shell
They have the same number of electron orbitals