What are monatomic and diatomic molecules?

Name the element represented by the symbol $\mathrm{K}$. 

Name the element represented by the symbol $\mathrm{Pb}$.

Name the element represented by the symbol $\mathrm{Zn}$.

Name the element represented by the symbol $\mathrm{Br}$.

Name the element represented by the symbol $\mathrm{Cl}$.