**Electron Configuration Practice Worksheet Answers**. 21) 1s 2 2s 2 2p 6 3s 1 sodium 22) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 6 ruthenium The electron configurations in this worksheet assume.

Electron configurations for the first period. The electron configurations in this worksheet assume. Electron configurations for the second period.