Iodine trifluoride IF3 is a molecule that consists of one iodine atom and three fluorine atoms. To determine its geometry and polarity, we need to consider the electron domains around the central atom iodine and the electronegativity difference between iodine and fluorine.
1. Geometry:
Iodine has 7 valence electrons, and each fluorine atom has 7 valence electrons. In IF3, one electron from iodine is shared with each fluorine atom to form a single bond. This leaves two lone pairs on the iodine atom. Therefore, there are a total of 5 electron domains around the central iodine atom 3 single bonds and 2 lone pairs .
According to the VSEPR Valence Shell Electron Pair Repulsion theory, the electron domains will arrange themselves to minimize repulsion. In the case of IF3, the electron domain geometry is trigonal bipyramidal. However, since there are two lone pairs, the molecular geometry is different from the electron domain geometry. The two lone pairs occupy the equatorial positions, and the three fluorine atoms occupy the axial positions, forming a T-shaped molecular geometry.
2. Polarity:
Polarity is determined by the electronegativity difference between the atoms in a molecule and the molecular geometry. Fluorine is more electronegative than iodine, so the I-F bonds are polar. In a T-shaped molecular geometry, the bond dipoles do not cancel each other out, resulting in a net dipole moment. Therefore, the IF3 molecule is polar.