O²⁻ ion
[He] 2s² 2p⁶, the same as neon. 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.
O2-Oxygen ion, 10 electrons
[He] 2s2 2p6
In full: 1s² 2s² 2p⁶. O gains 2 electrons into 2p. Same electrons as neon (Ne).
O gains 2 electrons into 2plike Ne
- Blockp block
- Period2
- Group16
- Outer shell8
- Unpaired0
- MagneticDia
Last electron 2p
- n2shell
- l1p subshell
- m+1orbital
- s−½spin down
Step by step
- Oxygen has 8 electrons: [He] 2s² 2p⁴.
- The ion has 2 more, 10 electrons. Add them in the usual filling order.
- O gains 2 electrons into 2p.
- O²⁻ ion: [He] 2s² 2p⁶, in full 1s² 2s² 2p⁶.
O²⁻ ion: the numbers
| Atomic number | 8 |
|---|---|
| Electrons | 10 |
| Period | 2 |
| Group | 16 |
| Block | p block |
| Electrons in the outer shell | 8 |
| Unpaired electrons | 0 |
| Magnetic | diamagnetic |
| Last electron | 2p: n = 2, l = 1, m = +1, s = −1/2 |
O²⁻ ion: quick answers
What is the electronic configuration of O²⁻?
O²⁻ has 10 electrons: 1s² 2s² 2p⁶, or [He] 2s² 2p⁶, the same as neon. O gains 2 electrons into 2p.
How many unpaired electrons are there in O²⁻?
O²⁻ has 0 unpaired electrons, so it is diamagnetic.
Why does O form the O²⁻ ion?
Gaining 2 electrons completes its outer shell: [He] 2s² 2p⁶, the same as neon.