(4.7) Bonding Theories (pg. 240-246)
hybridization
several atomic orbitals mix to form the same total number of equivalent hybrid orbitals.
Identify How many sigma and how many pi bonds are in an ethyne molecule (C2H2)?
sigma 3 and pi 2
Classify What shape would you expect a simple carbon-containing compound to have if the carbon atom has the following hybridizations?
sp2 double bond sp3 triple bond sp single bond Answer: trigonal planar tetrahedral linear
VSEPR theory
that the repulsion between electron pairs causes molecular shapes to adjust so that the valence-electron pairs stay as far apart as possible.
Explain Use VSEPR theory to predict bond angles in the following covalently bonded molecules. Explain your predictions.
trigonal planar square planar linear Answer: 109.5° (tetrahedral) 107°(pyramidal) 105°(bent)
Identify What do scientists use VSEPR theory for?
valence-shell electron-pair repulsion theory to shown electron in 3D form. Answer: Each molecule assumes the shape that places valence electron pairs as far apart as possible.
bonding orbital
A molecular orbital that can be occupied by two electrons of a covalent bond
Describe What is a sigma bond? Describe, with the aid of a diagram, how the overlap of two half-filled 1s orbitals produces a sigma bond.
A sigma bond is a when two atomic orbitals combine to make molecular orbitals. They are symmetrical to the axis. Answer: A sigma bond is formed by the overlap of two orbitals along the axis between two nuclei. See Figure 8.13.
Review How are atomic and molecular orbitals related?
Atomic orbitals part and molecular whole. Answer: When two atoms combine, their atomic orbitals overlap to produce molecular orbitals. An atomic orbital belongs to a particular atom, and a molecular orbital belongs to a molecule as a whole.
pi bond
(symbolized by the Greek letter π pi ), the bonding electrons are most likely to be found in sausage-shaped regions above and below the bond axis of the bonded atoms
What do scientists use the VSEPR theory for?
In order to explain the three-dimensional shape of molecules, scientists use valence-shell electron-pair repulsion theory (VSEPR theory).
Describe How is orbital hybridization useful in describing molecules?
Information about molecular bonding and shape take place and shown. Answer: Orbital hybridization provides information about both molecular bonding and molecular shape.
How are atomic and molecular orbitals related?
Just as an atomic orbital belongs to a particular atom, a molecular orbital belongs to a molecule as a whole.
In what ways is orbital hybridization useful in describing molecules?
Orbital hybridization provides information about both molecular bonding and molecular shape.
sigma bond
When two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting two atomic nuclei
tetrahedral angle
a bond angle of 109.5 degrees that results when a central atom forms four bonds directed toward the center of a regular tetrahedron
molecular orbital
orbitals that apply to the entire molecule
