# Does potassium metal have isotopes?

This site reports that there are 24 isotopes of potassium. Of course, since it is potassium, $Z = 19$ (why?).
The common isotopes are ""^39K (93.3%), and ""^41K (6.7%). If we take the weighted average of these 2 major isotopes we get very close to the average atomic mass, $39.0983 \text{ amu}$.