Argon (Ar)
[Ne] 3s² 3p⁶. 0 unpaired electrons, period 3, group 18, p block.
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.
ArArgon, Z = 18, 39.95 u
[Ne] 3s2 3p6
In full: 1s² 2s² 2p⁶ 3s² 3p⁶
- Blockp block
- Period3
- Group18
- Valence8
- Unpaired0
- MagneticDia
Last electron 3p
- n3shell
- l1p subshell
- m+1orbital
- s−½spin down
Step by step
- Argon has 18 electrons.
- Fill in (n + l) order: 1s² 2s² 2p⁶ 3s² 3p⁶.
- Write the subshells in order of n: 1s² 2s² 2p⁶ 3s² 3p⁶.
- Replace the neon core with [Ne]: [Ne] 3s² 3p⁶.
Argon (Ar): the numbers
| Atomic number | 18 |
|---|---|
| Atomic mass | 39.95 u |
| Period | 3 |
| Group | 18 |
| Block | p block |
| Valence electrons | 8 |
| Unpaired electrons | 0 |
| Magnetic | diamagnetic |
| Last electron | 3p: n = 3, l = 1, m = +1, s = −1/2 |
Argon (Ar): quick answers
What is the electronic configuration of argon?
Argon has 18 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶, or [Ne] 3s² 3p⁶ in short.
How many unpaired electrons does argon have?
Argon has 0 unpaired electrons, so it is diamagnetic. Put one electron in each box of a subshell before pairing (Hund’s rule) to see them.
What are the quantum numbers of the last electron of argon?
The last electron goes into 3p: n = 3, l = 1, m = +1, s = −1/2. Orbitals fill from m = −l up, spin +½ first.