Question

I'm confused by the aufbau principle in electron configuration. My textbook cites the example of

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^3

But wouldn't it be 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^3? Thanks! I'll give a medal and best answer

Answer 1

If you're writing the elemental form it would be the top one, but if it was to be ionized, the order of the bottom one is what would be followed.