Question 8
Potassium has atomic number 19, so its configuration is 2, 8, 8, 1. Where does it sit in the periodic table?
The right answer is the one marked above.
Period 4, group I.
- Electrons occupy 4 energy levels → period 4.
- The last level holds 1 electron → group I.
Watch the trap in “period 4, group IV”: it takes the 4 from the wrong place. The period counts the levels; the group counts what is in the last one, and here that is a single electron.