Valence Bond Theory

Question 1

What is valence bond theory?

Answer 1

Describes a covalent bond as resulting from the overlap of half-filled atomic orbitals, one for each atom.

Question 2

Each half-filled atomic orbital contains a single what?

Answer 2

Electron

Question 3

Two orbital can overlap when they what?

Answer 3

Partially occupy the same region of space.

Question 4

Orbitals must be at specific distance and what?

Answer 4

Orientation to each other in order to overlap effectively.

Question 5

More Overlap = what?

Answer 5

Stronger Bond

Question 6

How do sigma bonds form?

Answer 6

End-to-end overlap along the internuclear axis.

Question 7

What are the possible sigma bonds?

Answer 7

s-s, s-p, and p-p

Question 8

How do pi bonds form?

Answer 8

Side-to-side overlap on the opposite side of the internuclear axis. Both p orbitals must be parallel for a pi bond to form.

Question 9

All single bonds are what?

Answer 9

Sigma bonds

Question 10

Multiple bonds (double-bonds, triple-bonds, etc.) consists of what?

Answer 10

One sigma bond and one or more pi bond.

Question 11

What is hybridization?

Answer 11

Combining the wavefunctions for multiple atomic orbitals.

Question 12

What is the point of hybridization?

Answer 12

To form new atomic orbitals that are more suitable for the atom to form bonds.

Question 13

Hybridization does not exist in what?

Answer 13

Isolated atoms

Question 14

A set of hybrid orbitals is generated by combining what?

Answer 14

Atomic orbitals.

Question 15

All orbitals in a set of hybrid orbitals are what?

Answer 15

Equivalent in shape and energy

Question 16

Hybrid orbitals overlap to form what?

Answer 16

Sigma bonds

Question 17

Unhybridized orbitals overlap to form what?

Answer 17

Pi bonds

Question 18

sp Hybridization

Answer 18

S orbital combines with a p orbital which is equal to 180 degrees.

Question 19

Sp^2 Hybridization

Answer 19

This hybridization ends up as a trigonal planar.

Question 20

How to find number of domains in hybridization?

Answer 20

Add the superscripts of the orbitals and that should equal the number of domains (sp^2) —> 1 + 2 = 3

Question 21

sp^3 Hybridization

Answer 21

An s orbital combines with 3 p orbitals which are equal in 109.5 degrees apart.

Question 22

sp^3d Hybridization

Answer 22

s orbital + 3 p orbitals + d orbital which equal into 90 or 120 degrees apart.

Question 23

sp^3d^2 Hybridization

Answer 23

s orbital + 3 p orbitals + 2 d orbitals which equal to 90 degrees apart.

Question 24

When is best to use hybridization?

Answer 24

Works well for molecules containing small central atoms.

Question 25

Sigma Bonds

Answer 25

Made from hybrid orbitals, electron density is along internuclear axis and can rotate freely.

Question 26

Pi Bonds

Answer 26

Made from unhybridized p orbitals, electron density is above and below the internuclear axis, restrict rotation.