Electron Pair Geometries + Molecular Geometry + Hybridization Diagram | Quizlet

Linear

2 pairs

No lone pairs = Linear (180°)

Trigonal Planar

3 Electron Pairs

-

0 lone pairs = Trigonal Planar (120°)

1 lone pairs = Bent (<120°)

Tetrahedral

4 Electron Pairs

-

0 lone pairs = Tetrahedral (109.5°)

1 lone pairs = Trigonal Pyramid (<109.5° ~107°)

2 lone pairs = Bent (<109.5° ~105°)

Trigonal Bipyramidal

5 Electron Pairs

-

0 lone pairs = Trigonal Bipyramidal (90°, 120°)

1 lone pairs = Seesaw (<90°, <120°)

2 lone pairs = T structure (<90°)

2 lone pairs = Linear (180°)

Octahedral

6 Electron Pairs

-

0 lone pairs = Octahedral (90°, 90°)

1 lone pairs = Square Pyramidal (90°, <90°)

2 lone pairs = Square Planar (90°)

TERM

Electron Geometry

DEFINITION

describes the structure of the electron pairs around the central atom

TERM

Molecular Shape

DEFINITION

The shape (also called molecular geometry) is the arrangement of atoms around the central atom.

*The geometry is defined by the atoms NOT the electron pairs.

VESPR Theory (Valence Shell Electron Pair Repulsion)

electron geometry catagories

Linear, Trigonal Planar, Tetrahedron, Trigonal Bipyramidal, Octahedral

Molecular shape is the same as the electron pair geometry when

none of the structural electron pairs are non bonding (lone pair) electrons.

no lone pairs on central atom

The shape is the same as the electronic geometry.

hybrid orbitals

orbitals of equal energy produced by the combination of 2 or more orbitals on the same atom

Relation between Structural Pairs and Hybridization

Are lone pairs included in determining the electron pair structure?

yes

The number of structural pairs is equal to

the number of atoms bonded to a central atom + the number of lone pairs on the central atom.

if molecular shape and electron pair geometry are the same and the surrounding atoms are the same , then

the molecule is non-polar exception is square planar

3 part valence bond theory:

1. Valence atomic orbitals on adjacent atoms overlap.

2. Each pair of overlapping valence orbitals is occupied by two valence electrons to form a chemical bond.

3. Valence electrons are either involved in bonding between two atoms (shared bonding pairs) or reside on a single atom (nonbonding lone pairs).

A px orbital can form a σ bond with

another px orbital, an s orbital, or a dx2-y2 orbital. The other two orbitals, py and dxy, do not have lobes of electron density that point along the x- axis.

hybrid orbitals

equal-energy orbitals that are the combination of an atom's atomic orbitals.

Relation Between Structural Pairs and sp, sp 2, and sp 3 Hybridization

A single bond (one line) represents

a sigma bond

a double bond (two lines) represents

one sigma bond and one pi bond

a triple bond (three lines) represents

one sigma bond and two pi bonds.

the pi bond is a weaker bond than the sigma bond because

pi bond is sideways overlap, sigma is direct head on overlap of orbitals

Relationship between Hybridization and Number of Possible Pi Bonds.

Can compounds with 5 or 6 structural pairs form p-p pi bonds?

NO

Isomers

two or more substances that have the same chemical formula but have different properties because of the different arrangement of atoms. Molecules with pi bonds are one example of compounds that can exist as more than one isomer.

p orbitals at 90 degrees

do not form pi bonds

sigma bonds are

hybridized

pi bonds are

unhybridized

molecular orbital (MO) theory

Developed by Robert Mullikan

Orbitals in a molecule are delocalized (they are shared in the molecule) and treated as waves.

Predicts the shapes and energies of orbitals that contain no electrons.

Predicts paramagnetism much more accurately

Orbitals in the MO theory

Bonding orbitals in sigma and pi

Increase electron density between atoms

predicts bonding

Antibonding sigma or pi

describes interference between electron waves.

no electrons between atoms = no bonding

No bonding orbitals.

molecular geometry

is defined by the atoms NOT the electron pairs.

anti-bonding orbitals are ________ in energy

higher

Drawing Molecular orbital diagrams

1.Identify valence orbitals

2.Place the valence on the outside of the drawing

molecular orbitals are placed between with one bonding and one antibonding for each valence orbital

3.Then connect the valence orbitals to the molecular orbital via a dashed/dotted line to 4.show how we are forming the orbitals.