Molecular shape of BrF3 by VSEPR theory
Electronic shape is trigonal bipyramidal.
Molecular shape is T-shaped.
To determine the molecular shape of BrF3 using the Valence Shell Electron Pair Repulsion (VSEPR) theory, you need to follow these steps:
Step 1: Count the number of valence electrons of each atom. Bromine (Br) belongs to Group 7A, so it has 7 valence electrons. Fluorine (F) belongs to Group 7A as well, so each fluorine atom has 7 valence electrons. Since we have three fluorine atoms, the total number of valence electrons for the molecule BrF3 is:
1 (bromine) + 3 (fluorine) = 1 + 3(7) = 22 valence electrons.
Step 2: Determine the central atom. In BrF3, bromine (Br) is the central atom since it is less electronegative than fluorine and can form more bonds.
Step 3: Build the initial structure. Place the central atom (Br) surrounded by the three fluorine atoms (F) in a trigonal bipyramidal arrangement. This means one fluorine atom is bonded to the bromine atom, and the other two fluorine atoms are placed at the equatorial positions.
Step 4: Distribute the valence electrons in the structure. Start by forming single bonds between the central atom (Br) and the three surrounding fluorine atoms (F). This will account for eight electrons (2 for each bond). After forming these bonds, subtract the total number of electrons used from the total number of valence electrons calculated earlier.
22 - 8 = 14 valence electrons remaining.
Step 5: Place the remaining valence electrons on the outer atoms. In this case, distribute the 14 remaining valence electrons around the three fluorine atoms, ensuring each atom has an octet (except for the central atom). Place these electrons as lone pairs on the outer atoms until all the remaining electrons are used.
Step 6: Determine the molecular shape. In BrF3, the lone pairs and bonding pairs of electrons influence the shape. By examining the structure, we can see that there are two lone pairs of electrons on the central bromine atom. According to VSEPR theory, lone pairs exert more repulsion on surrounding atoms than bonded pairs.
Because of this, the two lone pairs on bromine will push the fluorine atoms closer to each other, resulting in a distorted trigonal planar shape. This gives BrF3 a T-shaped molecular shape, where the three fluorine atoms are oriented in a "V" shape, with the bromine atom at the center and the lone pairs and fluorine atoms in a T-shaped arrangement.
Therefore, the molecular shape of BrF3 is T-shaped based on the VSEPR theory.