Ion Builder (H → Kr)
Change electrons to build ions and instantly see shells + spdf notation update.
Build an ion
Z 12
Symbol Mg
Charge 0
Adjust electrons
Electrons: 12
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- Extra spacing supports readability.
- Colour is paired with labels (s / p / d / f).
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Shell arrangement
spdf notation
Tip: For transition metal ions, electrons are removed from 4s before 3d.
Challenge mode
Result: —
Reminder: protons stay the same. Only the number of electrons changes when ions form.
Visual explanation
Orbitals usually fill in this order (first 36 e⁻):
1s 2s 2p 3s 3p 4s 3d 4p.
Common exceptions: Cr and Cu rearrange slightly for extra stability
(Cr: 4s¹ 3d⁵, Cu: 4s¹ 3d¹⁰).
s-block
p-block
d-block
f-block (not used for 1–36)
Higher energy
absorbs light
Lower energy
ground state