Ca²⁺ ion
[Ar], 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.
Ca2+Calcium ion, 18 electrons
[Ar]
In full: 1s² 2s² 2p⁶ 3s² 3p⁶. Ca loses 4s². Same electrons as argon (Ar).
Ca loses 4s²like Ar
- Blocks block
- Period4
- Group2
- Outer shell8
- Unpaired0
- MagneticDia
Last electron 3p
- n3shell
- l1p subshell
- m+1orbital
- s−½spin down
Step by step
- Calcium has 20 electrons: [Ar] 4s².
- The ion has 2 fewer, 18 electrons. Remove them from the highest n first.
- Ca loses 4s².
- Ca²⁺ ion: [Ar], in full 1s² 2s² 2p⁶ 3s² 3p⁶.
Ca²⁺ ion: the numbers
| Atomic number | 20 |
|---|---|
| Electrons | 18 |
| Period | 4 |
| Group | 2 |
| Block | s block |
| Electrons in the outer shell | 8 |
| Unpaired electrons | 0 |
| Magnetic | diamagnetic |
| Last electron | 3p: n = 3, l = 1, m = +1, s = −1/2 |
Ca²⁺ ion: quick answers
What is the electronic configuration of Ca²⁺?
Ca²⁺ has 18 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶, or [Ar], the same as argon. Ca loses 4s².
How many unpaired electrons are there in Ca²⁺?
Ca²⁺ has 0 unpaired electrons, so it is diamagnetic.
Why does Ca lose its outer electrons first?
The electrons in the outermost shell are held least strongly, so they are removed first, leaving [Ar].