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Electron groups repel one another through coulombic forces
They will spread as far apart as possible on a molecule's central atom
- 1 single bond
- 1 double bond
- 1 triple bond
- 1 lone (unshared) pair of electrons 1 electron group: VSEPR Theory: Valence shell electron pair repulsion The five major electron group geometries:
e
groups Geometry Structure Ideal bond angle 2 Linear 3 Trigonal planar 4 Tetrahedral 5 Trigonal bipyramidal 6 Octahedral Chapter 10: Chemical bonding II: Molecular shapes and bonding
Electron group geometries
Lone pairs will only be placed in equatorial positions in the trigonal bipyramidal electron group geometry. 5 electron groups with lone pairs
Two lone pairs in an octahedral electron group geometry will add across from each other to minimize lone pair- lone par repulsions. 6 electron groups with lone pairs
What is the electron group and molecular geometry of IBr 5? Draw its flat Lewis structure and its 3-dimensional structure. What is the electron group and molecular geometry of ICl 2
- ? Draw its flat Lewis structure and its 3-dimensional structure. Geometry practice
The dipoles of polar bonds will add together geometrically to form a net dipole moment for the molecule. Molecules with a net dipole moment are polar. H 2 O: CO 2 : BF 3 : CH 2 F 2 : CO 3 2 - : Molecular shape and polarity
The one s and three p orbitals in carbon's valence shell combine together into 4 equivalent hybrid orbitals so carbon can make 4 bonds. Energy 2s 2p hybridization four equal-energy sp 3 hybrid orbitals According to VSEPR, four equivalent hybrid orbitals (each containing one electron group) will best fit around a central atom with a ______________ geometry. Any time there's a _______________ electron group geometry, the hybridization of the central atom is ____. sp 3 hybrid orbitals
molecular geometry:
electron groups on central atom:
NH 3 : electron group geometry: (The number of electron groups on the central atom is the number of hybrid orbitals that need to be formed!) Energy 2s 2p hybridization sp 3 hybrid orbitals N (three unpaired electrons to form bonds, and one lone pair!) sp^3 hybrid orbitals
CO 2 : 2 electron groups around C, so 2 hybrid orbitals Energy 2s 2p hybridization two sp hybrid orbitals C (central atom) two unhybridized p orbitals An sp hybridized central atom will be ________ in shape. sp hybridized C: sp hybridization
The bonds in valence bond theory are classified by their positions relative to the two bonding atoms. If two half- filled orbitals combine straight between the two atoms, it's called a σ (sigma) bond. When two half-filled p orbitals combine side-by-side, it's called a π (pi) bond. A single bond from Lewis theory like the C–H bonds in CH 4 is made of a single σ (sigma) bond. A double bond from Lewis theory like the C=C bond in C 2 H 4 is formed by one σ bond and one π bond. σ and π bonds
