SolutionsPeriodic Table
1. Electron configurations
Write the electron configuration of carbon (Z = 6), nitrogen (Z = 7), oxygen (Z = 8) and sodium (Z = 11).
- C: 1s2 2s2 2p2
- N: 1s2 2s2 2p3
- O: 1s2 2s2 2p4
- Na: 1s2 2s2 2p6 3s1
2. A family
What do fluorine, chlorine, bromine and iodine have in common?
They belong to the same group (column) of the periodic table, the halogens: they have seven electrons in their outermost shell (s2p5) and are one short of filling it. That is why their chemical properties are similar.