Molecular Shapes Flashcards
what is the VSPER Theory
valence shell electron pair repulsion theory
states that valence shell electron pairs will repel themselves as fa apart as possible in the 3D of space
the shape of a molecule or ion is a shape that keeps repulsive forces to a minimum
bond pair repulsions angles in molecules without lone pairs
1 or 2 bond pairs - linear - 180 degrees
3 bond pairs - trigonal planar - 120 degrees
4 bond pairs - tetrahedral - 109.5 degrees
all bond pair bond pair repulsions are equal
order of repulsive power between bonds
LP - LP > BP - LP > BP - BP
how are the angles between lone pairs and bond pairs changed
lone pairs have greater repulsive power than bond pairs so their presence will affect (increase) the angles of the bonds as they push the bond pairs away.
bond pair and lone pair repulsions angles in molecules with lone pairs
3 BP and 1 LP
angle is 107 degrees
shape is pyramidal
2 BP and 2 LP
angle is 104.5 degrees
shape is bent