Your question reveals a common confusion between orbitals and shells.
Chlorine has three electron shells: the first, second and third.
The first shell has just the one orbital, the 1s
The second shell has two sub-shells, the 2s and the 2p. There are three p orbitals in the 2p sub-shell. Each orbital can hold two electrons, so there are eight electrons maximum in the second shell.
The third shell likewise has two sub-shells, the 3s and the 3p, but the 3p is not completely filled, leaving room for one more electron. When chlorine gains this electron it will become a Cl- ion.
This is summed up in the electron configuration
1s22s22p63s23p5.
The electron configuration of chlorine is 1s2 2s2 2p6 3s2 3p5. Each separated letter in that notation represents a distinct electron orbital. Therefore, there are 5 electron orbitals in chlorine.
Chlorine has 3 energy levels. These energy levels are designated as K, L, and M.
Bromine has 4 electron shells.
Sodium has three electron shells.
Uranium has 92 electrons, which means it has 7 electron shells.
Francium has seven electron shells; electrons per shell: 2, 8, 18, 32, 18, 8, 1.
Rubidium has 5 electron shells. The electron configuration of rubidium is [Kr]5s1.
The electron configuration of chlorine is 1s2 2s2 2p6 3s2 3p5. Each separated letter in that notation represents a distinct electron orbital. Therefore, there are 5 electron orbitals in chlorine.
Chlorine has 3 energy levels. These energy levels are designated as K, L, and M.
Your question reveals a common confusion between orbitals and shells. Chlorine has three electron shells: the first, second and third. The first shell has just the one orbital, the 1s The second shell has two sub-shells, the 2s and the 2p. There are three p orbitals in the 2p sub-shell. Each orbital can hold two electrons, so there are eight electrons maximum in the second shell. The third shell likewise has two sub-shells, the 3s and the 3p, but the 3p is not completely filled, leaving room for one more electron. When chlorine gains this electron it will become a Cl- ion. This is summed up in the electron configuration 1s22s22p63s23p5.
Aluminium has three electron shells with 2,8,3 electrons each.
Magnesium has three electron shells. The electron configuration is 2,8,2
Polonium has 6 electron shells.
Bromine has 4 electron shells.
Helium has a total of 1 electron orbital. This electron orbital can hold a maximum of 2 electrons.
Sodium has three electron shells.
There are 17 paired electrons in a chlorine atom because it has 17 protons and 17 electrons, with each electron occupying a specific energy level and orbital.