Chp 1—Covalent bonding & shapes of molecules

Question 1

vitalism

Answer 1

belief that organic compounds must come from a living source

Question 2

disproved vitalism

Answer 2

Wohler - 1828 - synthesized urea

Question 3

each shell holds _____ electrons

Answer 3

2n²

n = shell #

Question 4

shells divided into…

names

Answer 4

orbitals

s — 1/shell

p — 3/shell 2+

d — 5/shell 3+

Question 5

3 rules for filling of shells

Answer 5

Aufbau principle

Pauli exclusion principle

Hund’s rule

Question 6

Aufbau principle

Answer 6

lower energy orbitals are filled first

Question 7

Pauli exclusion principle

Answer 7

only 2 electrons per orbital, and they must spin on their axes in opposite directions

Question 8

Hund’s rule

Answer 8

in orbitals of equal energy level, each is singly occupied before any is doubly occupied

Question 9

Pauling scale measures…

Answer 9

electronegativity

Question 10

electronegativity difference definition of ionic, polar covalent, and nonpolar covalent bonds

Answer 10

ionic: >1.9 difference in EN
polar: 0.5-1.9 difference in EN
nonpolar: <0.5 difference in EN

Question 11

nitrogen normal bonding patterns

Answer 11

N with 3 single bonds and 1 lone pair

Question 12

oxygen normal bonding pattern

Answer 12

O with 2 single bonds and 2 lone pairs

Question 13

halogen normal bonding pattern

Answer 13

Cl with 1 single bond and 3 lone pairs

Question 14

exceptions to octet rule

Answer 14

• 3rd row elements (from either side) - have d orbitals
• small atoms - ex boron forms 3 single bonds

Question 15

formal charge =

Answer 15

FC = # VE in neutral unbonded atom - (all unshared electrons + ½ of shared electrons)

Question 16

+ FC =

Answer 16

atoms’ electrons in molecule < VE in unbonded atom

Question 17

– FC =

Answer 17

atoms’ electrons in molecule > VE in unbonded atom

Question 18

all H have __ formal charge

Answer 18

0

Question 19

resonance structures occur especially in molecules with…

Answer 19

𝝅 bonds

Question 20

rules for drawing resonance structures (5)

Answer 20

1. only electrons move, not atoms
2. obey rules of covalent bonding; 3rd period atoms may have up to 12 electrons in shells
3. keep track of lone pairs & formal charges; all structures must have same number of paired and unpaired electrons
4. use curved arrows to interconvert & ID structures
5. use double headed arrow between structures

Question 21

resonance stabilization

Answer 21

energy of the true hybrid is << the energy of any contributing structure

Question 22

orbitals with same energy

Answer 22

degenerate

Question 23

overlap model of bonding includes 2 bond types…

Answer 23

sigma bonds (𝝈)

pi bonds (𝝅)

Question 24

possible sigma bonds by orbital type

Answer 24

s + s

s + p

px + px

Question 25

possible pi bonds based on orbital type

Answer 25

py + py

pz + pz

Question 26

stronger type of overlap bond

Answer 26

sigma

Question 27

hybridization occurs with…

Answer 27

orthogonal oriented orbitals (no overlap)

Question 28

conservation of orbitals

Answer 28

of originals = # of hybrids

Question 29

total orbitals in sp3 hybridization of carbon

Answer 29

1 original (1s)

4 hybrids (2sp3)

Question 30

components of sp3 hybrid

Answer 30

1 s (25%)

3 p (75%)

Question 31

shape of an s + p hybridization

Answer 31

1 large lobe, 1 small back lobe (not drawn)

Question 32

drawn orbitals around sp3-hybridized C

bond angle

Answer 32

4, all sp3 hybrids

109.5°

Question 33

total orbitals in sp2 hybridization of carbon

Answer 33

1 original (1s)

3 hybrids (2sp2)

1 unhybridized (2p)

Question 34

drawn orbitals around sp2 hybridized C

bond angle

Answer 34

4 — 3 sp2 hybrids, 1 unhybridized p

120°

Question 35

shape of sp2 hybridized C

Answer 35

trigonal planar

Question 36

hybrid orbitals form ___ bonds, unhybridized orbitals form ____ bonds

Answer 36

sigma

pi

Question 37

total orbitals in sp hybridization

Answer 37

1 original (1s)

2 hybrids (2sp)

2 unhybridized (2p)

Question 38

drawn orbitals around sp-hybridized C

bond angle

Answer 38

4 — 2 sp hybrids, 2 unhybridized p

180°

Question 39

shape of sp hybridized C

Answer 39

linear

Question 40

components of sp2 hybrid

Answer 40

1 s (33%)

2 p (67%)

Question 41

components of sp hybrid

Answer 41

1 s (50%)

1 p (50%)

Question 42

constitutional isomers

Answer 42

different connectivity between atoms

Question 43

cis-trans isomerism arises from…

Answer 43

pi restriction of free rotation

Question 44

cis trans isomers are stable at _____ because ______

Answer 44

room temp

requires energy to change their form

Question 45

wave function

Answer 45

mathematical description of wave size, shape, orientation

Question 46

node

Answer 46

amplitude of the wave is 0 at the origin

there is 0 chance of finding an electron

Question 47

atomic orbital

Answer 47

unhybridized orbitals on an atom

Question 48

linear combination of atomic orbitals

Answer 48

hybridization

wave functions are combined

Question 49

molecular orbital

Answer 49

combination of atomic orbitals from different atoms

Question 50

constructive interference occurs when…

Answer 50

molecules collide at an orientation with e- in the same phase

Question 51

bonding molecular orbitals’ nodes vs antibonding

Answer 51

antibonding always have 1 more node

Question 52

molecular orbitals vs atomic orbitals in energy

Answer 52

energy of MOs << energy of AOs

Question 53

strength of pair repulsion vs bonded pair repulsion

Answer 53

lone pair repulsion >> bonded pair repulsion

Question 54

shape vs geometry

Answer 54

shape does not consider lone pairs

geometry considers lone pairs