Electron configuration practice
Use the periodic table to write the configuration, then build the orbital diagram.
1. Full configuration
Type each subshell with its electron count, like 1s2 2s2 2p6.
2. Noble gas abbreviation
Replace the inner electrons with the noble gas at the end of the previous period, like [Ne] 3s2 3p4.
3. Orbital diagram
Click a box to cycle through empty, ↑, ↓, ↑↓ and ↑↑. Energy increases going up.
Aufbau principleFill the lowest-energy subshells first.
Pauli exclusion principleAn orbital holds at most two electrons, with opposite spins.
Hund’s rulePut one electron in each orbital of a subshell, all spinning the same way, before pairing up.
4. Unpaired electrons
How many electrons are alone in their orbital?