Final answer:
The molecular geometry of BrF₅ is square pyramidal due to one lone pair and five bonding groups around the central bromine atom, resulting in minimized LP-BP repulsions.
Step-by-step explanation:
The molecular geometry of BrF₅ is determined by the arrangement of electron groups around the central bromine atom. Although BrF₅ has five groups around the central atom, which would suggest a trigonal bipyramidal geometry, one of these groups is a lone pair of electrons. This lone pair occupies an equatorial position in the trigonal bipyramid, leading to a square pyramidal geometry for the molecule. Lone pair-bonding pair (LP-BP) repulsions are minimized with this arrangement, as lone pairs tend to take up more space than bonding pairs. The Lewis structure of BrF₅ shows bromine at the center with five fluorine atoms attached and one lone pair of electrons on the bromine, making BrF₅ an exception to the octet rule.