The shape of [BrF4]- ion isa)Regular tetrahedronb)Square planarc)Trigo...
The shape of the [BrF4]- ion is square planar. To understand why, we need to look at the electron configuration of the bromine atom and the number of bonding electrons involved in the ion.
Bromine has 7 valence electrons, and each of the four fluorine atoms contributes one electron for bonding. Additionally, there is one extra electron due to the negative charge of the ion, resulting in a total of 12 valence electrons involved in bonding.
According to the VSEPR (Valence Shell Electron Pair Repulsion) theory, the molecular shape is determined by the repulsion of electron pairs around the central atom. In the case of [BrF4]-, the central bromine atom is surrounded by 4 bonding pairs of electrons and 1 lone pair.
The number of electron pairs around the central atom determines the electron pair geometry. In this case, with 5 electron pairs, the electron pair geometry is trigonal bipyramidal. However, the molecular shape is determined by the arrangement of the bonded atoms around the central atom, not including the lone pairs.
In the case of [BrF4]-, the lone pair of electrons occupies one of the equatorial positions in the trigonal bipyramidal geometry, causing the four fluorine atoms to take up the remaining positions. These fluorine atoms form a square planar arrangement around the central bromine atom.
Therefore, the shape of the [BrF4]- ion is square plan