Question

What is the full electron configuration of iron?

Answer 1

Well, for iron, `Z=26`. How did I know that?

Explanation:

And if there are 26 positively charged particles in the NEUTRAL atom....there MUST be 26 negatively charged particles WHIZZING round this nuclear core....

And we distribute these electrons according to the usual `"aufbau"` scheme...

`underbrace(1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)4s^(2)3d^(6))_"26 electrons AS REQUIRED"`

Equivalently we could represent this configuration by...

`[Ar]4s^(2)3d^6`