Organic Chemistry Exam 1

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1

What elements will we mainly be using in this course?

Hydrogen

Carbon

Oxygen

Nitrogen

Sulfur

Phosphorus

2

__________ are composed of H and C.

Hydrocarbons

3

__________ are composed of H C and O.

Lipids

4

__________ and some __________ are composed of H C O N and S.

Proteins

Amino acids

5

__________ and __________ are composed of H C O N S and P.

DNA

RNA

6

What is polar molecule?

A molecule that contains unequal sharing of electrons making the molecule charged.

7

What is a nonpolar molecule?

A molecule that contains equal sharing of electrons.

8

Give three reasons why Carbon is so important

1. Carbon makes strong homoatomic bonds

2. Carbon makes strong heteroatomic bonds

3. Carbon is varied

9

What is a homoatomic bond?

A bond between the same atoms

C-C

10

What is a heteroatomic bond?

A bond between different atoms

C-H

11

Carbon is varied. What does this statement mean and why is it important?

Carbon can have varied bonds. All of which are stable. The ability to make 3 types of bonds that are stable give variety to life.

C-C (Stable)

C=C (Stable)

CC (Stable)

12

What is a covalent bond?

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A bond in which electrons are shared.

13

What is an ionic bond?

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A bond in which electrons are transferred from one atom to another.

14

What does the shape of a molecule have to do with the polarity of it?

Linear molecules tend to have a perfect tug of war canceling out the charge making them nonpolar.

15

What is electronegativity?

The measure of the tendency of an atom to attract a bonding pair of electrons in a covalent bond

16

Water is special because of __________ __________.

Hydrogen bonds

17

The bulk of the mass of an atom is where?

In the nucleus

18

What is the atomic number?

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The number of protons which dictates the identity of the element.

19

What is the atomic mass / mass number?

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(atomic mass) - (atomic number) = Number of Neutrons

This number dictates the isotope.

20

In a neutral atom what two things must equal each other?

The number of protons must equal the number of electrons

21

What are the two types of charged ions?

Cation

Anion

22

Describe a cation

Cations lose electrons

# Protons > # Electrons

23

Describe an anion

Anions gain electrons

# Protons < # Electrons

24

Principal energy levels are divided in to __________. Name all four of these.

Subshells

s p d f

25

Each subshell is divided into __________. Each of these can only hold __________ electrons

Orbitals

Two

26

What is a valence shell?

The occupied electron shell with the highest energy

27

The electron configuration of Fluorine is 1s2 2s2 2p5. What is in the valence shell of Fluorine?

2s2 2p5

28

How many orbitals make up the following subshells?

s: __________ Orbitals

p: __________ Orbitals

d: __________ Orbitals

f: __________ Orbitals

s: 1 Orbital

p: 3 Orbitals

d: 5 Orbitals

f: 7 Orbitals

29

When forming ions, electrons will always be lost through the __________ shell. More specifically the __________ __________ shell.

Valence

Highest energy

30

What type of bonds are not carbon based?

Ionic bonds

31

What are the two types of covalent bonds?

Polar covalent

Nonpolar covalent

32

Define the following

1. Polar covalent bond

2. Nonpolar covalent bond

1. Polar covalent bond

- The unequal sharing of electrons (charged)

2. Nonpolar covalent bond

- The equal sharing of electrons

33

What is a lewis structure?

A drawing of a molecule that shows where every single valence electron is located.

34
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What do the group numbers tell you about an atom?

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The number of valence electrons each element has in each group

35

How do you calculate the number of bonds an element wants for a lewis structure?

Each atom wants a full octet, so subtracting the number of valence electrons an atom has from 8 will leave you with the number of bonds wanted by that atom.

36

What are the steps to drawing a Lewis structure?

1. Add up all of your valence electrons

2. Draw structure with only single bonds

3. Add in electrons or double bonds so that the bonds and electrons add up to the total number of valence electrons

37

How do you calculate formal charge?

FC = (# Valence electrons) - (# Lone Pairs) - (# Lines)

38
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What is the formal charge of N?

FC = (# Valence electrons) - (# Lone Pairs) - (# Lines)

FC = 5 - 0 - 4

FC = 1

Nitrogen has a formal charge of +1

39

What does VESPR theory stand for?

Valence Shell Electron Pair Repulsion

40

1. What does VESPR theory determine?

2. What does VESPR theory state?

1. The molecular geometry of a Lewis structure

2. Electrons in lone pairs or neighboring bonds repel each other

41

What is electron density?

The amount of lone pairs and bonds.

Each lone pairs counts as one

Each bond (single, double, or triple) counts as one

42
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What is the electron density of C?

2

43
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What is the electron density of C?

3

44

A pyramidal molecule contains the following:

Electron Density: __________

Lone Pairs: __________

Pyramidal

Electron Density: 4

Lone Pairs: 1

45

A bent molecule contains the following:

Electron Density: __________

Lone Pairs: __________

Bent

Electron Density: 4

Lone Pairs: 2

46

A tetrahedral molecule contains the following:

Electron Density: __________

Lone Pairs: __________

Tetrahedral

Electron Density: 4

Lone Pairs: 0

47

A trigonal planar molecule contains the following:

Electron Density: __________

Lone Pairs: __________

Trigonal planar

Electron Density: 3

Lone Pairs: 0

48

A Linear molecule contains the following:

Electron Density: __________

Lone Pairs: __________

Linear

Electron Density: 2

Lone Pairs: 0

49

What makes an atom Sp3 hybridized?

Surrounded by all single bonds

50

What makes an atom Sp2 hybridized?

Surrounded by at least one double bond

51

What makes an atom Sp hybridized?

Surrounded by at least two double bonds or one triple bond

52
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What is the hybridization of the carbon furthest to the right?

Sp2

53
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What is the Hybridization of both carbons?

Sp

54

What are sigma bonds?

The strongest bonds that form directly between atoms

55

What are pi bonds?

Weaker bonds that form above, below, in front, or behind the atoms

56

State the number of pi bonds and the number of sigma bonds in each of the following:

C-C

C=C

C=C

C-C

- 1 sigma bond, 0 pi bonds

C=C

- 1 sigma bond, 1 pi bond

C=C

- 1 sigma bond, 2 pi bonds

57

Resonance can't occur without __________ bonds

Pi bonds

58

What is resonance?

The movement of electrons around a molecule without making or breaking bonds

59

What are three ways you can draw resonance arrows?

1. From a lone pair to form a double bond.

2. From a double bond to form a lone pair

3. From a double bond towards a cation to form a new double bond

60

What is the Arrhenius definition of an acid?

Acids produce H3O+ (H+) in water

61

What is the Arrhenius definition of a base?

Bases produce OH- in water

62

What is the Bronsted Lowry definition of an acid?

Acids donate H+

63

What is the Bronsted Lowry definition of a base?

Bases accept H+

64

What is the Lewis-Acid-Base definition of an acid?

Acids are electron pair acceptors

65

What is the Lewis-Acid-Base definition of a base?

Bases are electron pair donors

66

Water is amphoteric, what does this mean?

It can act as a base or as an acid depending on the environment it is in

67

Lewis-Acid-Base equations always end in a(n) __________.

Adduct

68

What makes acids and bases strong?

Their ability to completely ionize in solution

69

What makes acids and bases weak?

They lack the ability to completely ionize in water

70

An acid with a small pKa is a __________ acid

Strong

71

An acid with a large pKa is a __________ acid

Weak

72

The stronger the acid the __________ its conjugate base

Weaker

73

Can a molecule be an acid if it doesn't contain an H?

No

74

How do you use hybridization to tell which atom is more acidic?

Sp3 Least acidic

Sp2 Moderately acidic

Sp Most acidic

75

How do you use electronegativity to predict acidity of a molecule?

- Only valid when comparing across periods not groups

- The molecule that has a more electronegative atom attached to the acidic H is more acidic.

76

Which acid is more acidic?

P-H or S-H

S-H because S is more electronegative than P.

77

How do you use resonance to predict the acidity of a molecule?

- React the molecule in question with a hydroxide ion (OH-)

- If the conjugate base can resonate, then the acid is strong

- If the conjugate base cannot resonate, then the acid is weak

78

What is a something to look for when trying to figure out if a reaction is a Lewis-Acid-Base reaction?

- An atom containing only 6 electrons around it without a charge.

- Most of these are in group 3 on the periodic table

79

How do you use the inductive effect to predict acidity?

- Molecules containing many electronegative atoms (i.e. F, Cl, O) are more acidic

- Molecules containing less electronegative atoms are less acidic

80

How do you use size to determine acidity?

- The size of an atom increases going down a group.

- The larger the atom the more acidic it is

81

Which molecule is more acidic?

H-Cl

H-I

H-I because the I is larger than the Cl. The space allows for the delocalization of the charge making it more stable.

82

What are hydrocarbons?

CxHy

83

What are saturated hydrocarbons?

- Hydrocarbons that are saturated with hydrogens

- Composed of all single C-C bonds

84

What are unsaturated hydrocarbons?

- Hydrocarbons that have at least 1 C=C double bond

- Octet is filled with C=C double bonds and then with hydrogens

85

1 degree of unsaturation is equal to how many pi bonds?

1

86

1 degree of unsaturation is equal to how many rings?

1

87

What is the equation that is used to find the degrees of unsaturation for hydrocarbons?

DOU = [2(#C) + 2 - (#H)] / 2

88

What is a constitutional Isomer?

Molecules that have the same molecular formula but different configurations.