Cl⁻ ion
[Ne] 3s² 3p⁶, the same as argon. 0 unpaired electrons, diamagnetic.
Element or ion
Type a symbol, a name or an atomic number, add a charge such as Fe3+ or Cl-, or tap an element in the table. Orbitals fill from m = −l up, spin +½ first.
Cl-Chlorine ion, 18 electrons
[Ne] 3s2 3p6
In full: 1s² 2s² 2p⁶ 3s² 3p⁶. Cl gains 1 electron into 3p. Same electrons as argon (Ar).
Cl gains 1 electron into 3plike Ar
- Blockp block
- Period3
- Group17
- Outer shell8
- Unpaired0
- MagneticDia
Last electron 3p
- n3shell
- l1p subshell
- m+1orbital
- s−½spin down
Step by step
- Chlorine has 17 electrons: [Ne] 3s² 3p⁵.
- The ion has 1 more, 18 electrons. Add them in the usual filling order.
- Cl gains 1 electron into 3p.
- Cl⁻ ion: [Ne] 3s² 3p⁶, in full 1s² 2s² 2p⁶ 3s² 3p⁶.
Cl⁻ ion: the numbers
| Atomic number | 17 |
|---|---|
| Electrons | 18 |
| Period | 3 |
| Group | 17 |
| Block | p block |
| Electrons in the outer shell | 8 |
| Unpaired electrons | 0 |
| Magnetic | diamagnetic |
| Last electron | 3p: n = 3, l = 1, m = +1, s = −1/2 |
Cl⁻ ion: quick answers
What is the electronic configuration of Cl⁻?
Cl⁻ has 18 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶, or [Ne] 3s² 3p⁶, the same as argon. Cl gains 1 electron into 3p.
How many unpaired electrons are there in Cl⁻?
Cl⁻ has 0 unpaired electrons, so it is diamagnetic.
Why does Cl form the Cl⁻ ion?
Gaining 1 electron completes its outer shell: [Ne] 3s² 3p⁶, the same as argon.