Explanation:
As you know, electrons are always moving. They spin very quickly around the nucleus of an atom. As the electrons zip around, they can move in any direction, as long as they stay in their shell. Any direction you can imagine — upwards, downwards, or sidewards — electrons can do it. Electrons are constantly spinning in those atomic shells and those shells, or orbitals, are specific distances from the nucleus. If you are an electron in the first shell, you are always closer to the nucleus than the electrons in the second shell.
