Electron Configuration Lab

Tap a box to change it: empty → ↑ → ↑↓ → ↓ → empty.

Full configuration

1. Type the number after the letter: 2p6 means 2p⁶. Spaces are optional.
2. The quick keys add to the box with the blue border. Tap a box to choose it.
3. Noble gas form: put the noble gas from the end of the row above in brackets, then write only what comes after it.
4. You may write 4s before 3d or 3d before 4s. Both are accepted.

Limits: s holds 2, p holds 6, d holds 10.1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p

A neutral atom has this configuration. What is it?

1. Check the limits. s holds 2, p holds 6, d holds 10. Any sublevel over its limit means not possible.
2. Count the electrons. In a neutral atom, electrons = protons = atomic number. That gives the element.
3. Compare with the ground state. Same as the filling order: ground state. An electron sits in a higher sublevel while a lower one is not full: excited state. (Cr and Cu are the two ground-state exceptions.)

An excited atom is still the same element. It has the same number of electrons, only with more energy.