# True or false? The maximum covalency in 2nd-period elements is 4. Why is this true if fluorine can only make one bond?

Carbon is the atom that can make four bonds at once, e.g. in ${\text{CH}}_{4}$ and other hydrocarbons. Not fluorine.
On the other hand, $\text{Br}$ and $\text{I}$ can make more than four bonds, as they can pool in $\left(n - 1\right) d$ orbitals to form hypervalent compounds such as ${\text{BrF}}_{5}$ and this beast (periodinane).