Chapter 3: Bonding

Question 1

Describe the appearance of s-, p-, and d-orbitals

Answer 1

Question 2

The 4 principle quantum numbers

Answer 2

principle quantum number (n)

azimuthal quantum number (l)

magnetic quantum number (ml)

spin quantum number (ms)

Question 3

principal quantum number (n)

Answer 3

a measure of SIZE (proximity to the nucleus)

possible values: 1 to infinity

indicates the energy level of an electron within the orbital

smaller # = closer to nucleus

Question 4

azimuthal quantum number (l)

Answer 4

indicate the SHAPE of the sub shells within an electron shell (n)

possible values: 0 to n-1

larger l value = higher energy

Question 5

s orbital

Answer 5

l = 0

spherical shape

Question 6

p orbital

Answer 6

l = 1

dumbell shape

Question 7

magnetic quantum number (ml)

Answer 7

indicates the ORIENTATION of the sub shell

possible values: -l to +l

Question 8

spin quantum number (ms)

Answer 8

indicates the SPIN of electrons within a given shell

possible values: +/- ½

Question 9

molecular orbitals

Answer 9

the resulting orbital when 2 atomic orbitals combine

Question 10

bonding orbital

Answer 10

the signs of the wave functions of the combining atomic orbitals are the SAME

lower-energy (more stable)

Question 11

antibonding orbital

Answer 11

the signs of the wave functions of the combining atomic orbitals are DIFFERENT

higher-energy (less-stable)

Question 12

How are molecular orbitals obtained (mathematically)?

Answer 12

by adding or subtracting the wave functions of the atomic orbitals

Question 13

If n atomic orbitals combine, how many molecular orbitals result?

Answer 13

n

(the number of orbitals must be conserved!)

Question 14

explain the energy diagram with atomic orbitals to molecular orbitals

Answer 14

Question 15

electrons found in the bonding orbital will …

Answer 15

stabilize the bond and hold the atoms together

Question 16

electrons found in the anti bonding orbitals will…

Answer 16

cause dissociation of the atoms

Question 17

sigma bonds (3)

Answer 17

all single bonds are sigma bonds (hold 2 electrons)

results when a MO is formed by head-to-head or tail-to-tail overlap of atomic orbitals

single bonds allow free rotation of atoms around the bond

Question 18

pi bonds (4)

Answer 18

when 2 p-orbitals line up side-by-side

a double bond consists of one pi bond on top of an existing sigma bond

a triple bond consists of 1 sigma bond and 2 pi bonds

double and triple bonds do NOT allow free rotation of atoms around the bond

Question 19

strength of sigma and pi bonds

Answer 19

sigma bonds are stronger than individual pi bonds

the strength of the bonds are additive, making double and triple bonds stronger than single bonds

Question 20

bond energy

Answer 20

energy required to break a bond

indicates the STRENGTH of a bond

higher bond energy = stronger bond

Question 21

hybridization

Answer 21

the concept of mixing two atomic orbitals to give rise to a new type of hybridized orbitals

Question 22

how are hybrid orbitals formed?

Answer 22

by mixing different types of orbitals

Question 23

sp3 orbitals

Answer 23

formed by combining 3 p orbitals and 1 s orbital

have a new, unique hybridized shape

Question 24

ex. calculating “s character” of an sp3 bond

Answer 24

an sp3 bond is the combination of 1 s orbital and 3 p orbitals (4 total)

1 s / 4 total = 25% s character

Question 25

degenerate orbitals

Answer 25

orbitals which have the same energy

Question 26

hybrid orbitals are used to form _______ bonds

Answer 26

sigma bonds

Question 27

unhybridized orbitals are used to form ______ bonds

Answer 27

pi bonds

Question 28

s character and p character of sp3 hybridized orbitals

Answer 28

s character: 25%

p character: 75%

Question 29

s character and p character of sp2 hybridized orbitals

Answer 29

s character: 33%

p character: 66%

Question 30

s character and p character of sp2 hybridized orbitals

Answer 30

s character: 50%

p character: 50%

Question 31

carbons with all singles bonds are ____ hybridized

Answer 31

sp3

Question 32

carbons with one double bond are ____ hybridized

Answer 32

sp2

(1 unhybridized p orbital is involved in the pi bond)

Question 33

carbons with 1 triple bond are ____ hybridized

Answer 33

sp

(2 unhybridized p orbitals are involved in pi bonds)

Question 34

determine hybridization of atoms

Answer 34

of pi bonds will equal the # of unhybridized p orbitals

of sigma bonds or lone pairs will equal the # of hybridized orbitals

(“groups” = bonds and lone pairs)

Question 35

resonance

Answer 35

describes the delocalization of electrons in molecules that have conjugated bonds

a way of describing bonding in certain molecules by the combination of several contributing structures into a resonance hybrid in valence bond theory

Question 36

conjugation

Answer 36

occurs when single and multiple bonds alternate, creating a system of unhybridized p-orbitals down the backbone of the molecule through which pi electrons can delocalize

Question 37

why are sigma bonds stronger than pi bonds?

Answer 37

they have more orbital overlap