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Chem 103 > Midterm 2 Part A > Flashcards

Midterm 2 Part A Flashcards

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1
Q

Chemical bonding: ___ that keeps atoms _____

A

Force

Together

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2
Q

3 types of chemical bonds

A

Ionic

Covalent

Metallic

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3
Q

Ionic Bonding: between a ___ and a ____. Involves a _____ of electrons

A

Metal

Nonmetal

Transfer

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4
Q

Ionic bonding: forms ____ structures , forms compounds that are ___,___,and brittle

A

Extended

Hard

Rigid

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5
Q

Ionic bonding: forms compounds that are poor _____ of heat and electricity in the ___ state

A

Conductors

Solid

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6
Q

Ionic bonding: forms good electrical conductors in the ___ or ____ phases

A

Molten

Aqueous

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7
Q

Ionic bonding: cation and anion are held together by attractive ______ forces given by Coulomb’s law

A

Electrostatic

E = (q1•q2)/d^2

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8
Q

What is lattice energy

A

Energy that is released when gaseous ions bond to form the ionic solid

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9
Q

What is lattic energy proportional to

And why is this important

A

The electrostatic force (E)

When looking at the trend for melting points of compounds we look at the size of the ions, and see the distance between them.

Larger distance= less lattice energy, meaning lower melting point

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10
Q

Lattice energy helps determine the _____ of the bond

A

Strength

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11
Q

If triangle H= (-770)J

What can we tell from this using the def of lattice energy

A

We need (-770)J to BREAK the ionic bond

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12
Q

Higher melting point requires _____(less/more) energy

A

More

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13
Q

What two things affect the melting point of a compound and why

A

Charges and distance between the atoms

These are the three variables on Coloumb’s law

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14
Q

Steps for determining melting point trends

A

1) look at charges
-elements in compounds with GREATER numerical charge have HIGHER melting point

2)if two compounds have elements of the same charge: look at atomic mass of elements in each compound

-greater atomic mass=larger distance between nucli= smaller LE=lower melting point

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15
Q

Covalent bonding: between a nonmetal and _____. Involves the sharing of _____.

A

Nonmetal

Electrons

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16
Q

Covalent bonding: forms compounds with _______structure as well as extended ______

A

Molecular

Structures

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17
Q

Covalent bonding: molecular compounds are typically gases or ____ with low melting or ____ points, whereas compounds with extended structures are ____ and rigid ____ with _____ melting points

A

Liquids

Boiling

Hard

Solids

High

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18
Q

What are the two types of covalent bonds and give an example of each

A

Pure covalent bonds (H2, O2, Cl2)

Polar covalent bonds (HF)

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19
Q

Pure covalent bonds have ____ sharing of electrons because of the SAME ___ of the bonded atoms

A

Equal

EA

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20
Q

Why do polar covalent bonds have an unequal sharing of electrons,

and which atom will draw electrons more strongly

A

Because the atoms have a difference in electro negativity

The atom with the HIGHER electronegativity will draw electrons more strongly

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21
Q

How can bond polarity be determined and what is the formula for this

A

Determined by calculating
triangle(EN)

triangle(EN)=| (En positive) - (En negative) |

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22
Q

Explain the difference between electron affinity and electronegativity

A

Electron affinity- referring to the ability of an ISOLATED atom in the GAS state to add an electron

Electronegativity- ability of an atom in a BOND to DRAW electron density

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23
Q

Metallic bonding: between a metal and a ___. Has an _____ structure of atoms in “sea” of ______ electrons

A

Metal

Extended

Delocalized

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24
Q

Metallic bonding: what does the sea of electrons do

A

Acts as a glue to keep the cations together

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25
Q

Metallic bonding: Metals are malleable and ____. They are good conductors of heat and _____. They have moderately _____ melting and boiling points.

A

Ductile

Electricity

High

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26
Q

What is a stable electron configuration

A

Valence electrons are distributed so that each atom has 8 electrons, 2 for hydrogen

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27
Q

Steps for drawing lewis structure for covalent bonds

A

1) determine the total # of ve

2) use pairs to join all atoms

3) distribute remaining electrons

4) if compound has a (-) or (+) charge MUST PUT SQUARE BRACKETS AROUND AND INDICATE CHARGE

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28
Q

Exceptions to the octet rule and why this happens

(What is this called)

A

Elements in period 3 and beyond can have 10 or 12 ve

Because they can use their d orbitals in bonding

(Expanded octet)

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29
Q

Incomplete octets: what does this mean and what elements are they

A

Elements may have LESS that 8 electrons

Beryllium, Boron, and aluminum

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30
Q

Odd electron species: what is it and how to deal with it

A

There could be one unpaired electron

This electron must be placed with the LEAST electronegative atom of the molecule

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31
Q

Formal charge: the difference between the # of ____ ___ in the free atom and the # of electrons _____ to the atom

A

Valence electrons

Assigned

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32
Q

Formal charge formula and what must you do to calculate this

A

FC on an atom= ve-(e in lone pairs)- (1/2)(e in covalent bonds/pairs)

Need to draw the Lewis structure to calculate formal charge on any element in the compound

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33
Q

All formal charges MUST __up to the overall ___ of the molecule

A

Add

Charge

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34
Q

Low formal charges are ___, FC of ___ is the most stable

A

Preferred

0

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35
Q

(+) formal charges are preferred on the ____ electronegative atom, and (-) FC’s are preferred on the ____ electronegative atom

A

Less

More

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36
Q

What is a resonant structure

A

Molecules that have MORE than 1 plausible Lewis structure. The true structure is then a resonance hybrid of all the contributing structures. Bonding electron density can therefore be delocalized over more than two atoms

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37
Q

What symbol represents a resonant structure

A

<—->

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38
Q

How to show a resonant structure

A

Insert picture of 03

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39
Q

Single bond has a bond order of ____

Double bond has a bond order of ___

A

1

2

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40
Q

In resonant structures all bonds are equivalent in ____ and _____

A

Length

Strength

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41
Q

Lower bond order= ___ and ____ bond

Higher bond order=___ and ____ bond

A

Weaker, longer

Stronger, shorter

42
Q

What is the prediction of molecular shape based on

A

The EXTENT of REPULSION between two electron pairs

43
Q

Lewis structures: electron pairs are arranged around the central atom to ____ repulsion

A

Minimize

44
Q

of electron pairs around central atom?

Molecular shape: AX2

Shape?

Bond Angles?

A

2

Linear

2 bonding pairs

45
Q

In the form AXE what do A, X, E represent?

A

A= central atom

X= terminal atom

E= lone pair

46
Q

of electron pairs around central atom?

Molecular shape: AX3

Shape?

Bond Angles?

A

3

Trigonal planar

120 degrees bond angle

47
Q

of electron pairs around central atom?

Molecular shape: AX2E

Shape?

Bond Angles?

A

3

Bent, angular, v shape

Less than 120, which is the ideal bond angle (because lone pair pushes on bonded pairs with more force)

48
Q

Why are some bond angles smaller than the ideal bond angles

A

The presence of a lone pair

(Lone pairs occupy more space. They exert a stronger force of repulsion that a bonded pair)

49
Q

of electron pairs around central atom?

Molecular shape: AX4

Shape?

Bond Angles?

A

4

Tetrahedral

109.5

50
Q

of electron pairs around central atom?

Molecular shape: AX3E

Shape?

Bond Angles?

A

3 bonding, 1 lone

Trigonal pyramidal

Less than 109.5

51
Q

of electron pairs around central atom?

Molecular shape: AX2E2

Shape?

Bond Angles?

A

2 bonding, 2 lone

Bent, angular

Less than 109.5

52
Q

When labelling bond angles that are “less than” where do you always draw the arrow in between

A

2 bonding pairs

(Instead of a bonding pair and lone pair)

53
Q

of electron pairs around central atom?

Molecular shape: AX5

Shape?

Bond Angles?

A

5 bonding

Trigonal bipyramidal

120 degrees

54
Q

of electron pairs around central atom?

Molecular shape: AX4E

Shape?

Bond Angles?

A

4 bonding, 1 lone

See saw

Smaller than 120 and 90

55
Q

of electron pairs around central atom?

Molecular shape: AX3E2

Shape?

Bond Angles?

A

3 bonding, 2 lone

T shape

Less than 90

56
Q

of electron pairs around central atom?

Molecular shape: AX2E3

Shape?

Bond Angles?

A

2 bonding, 2 lone

Linear

180 degrees

57
Q

of electron pairs around central atom?

Molecular shape: AX6

Shape?

Bond Angles?

A

6 bonding

Square pyramidal

90 degrees

58
Q

of electron pairs around central atom?

Molecular shape: AX5E

Shape?

Bond Angles?

A

5 bonding, 1 lone

Square pyramidal

Less than 90 degrees

59
Q

of electron pairs around central atom?

Molecular shape: AX4E2

Shape?

Bond Angles?

A

4 bonding, 2 lone

Square planar

90 degrees

60
Q

What is electron group arrangement

A

Only considers how many THINGS the central atom is connected to (other atoms and lone pairs)

61
Q

How to determine electron group arrangement shape

A

1) determine type (AXE thing)
2) add up the subscripts of X and E and March that number to the corresponding shape

linear= 2

trigonal planar= 3

Tetrahedral= 4

Trigonal bipyramidal= 5

Octahedral= 6

62
Q

Valence Bond Theory: a _____bond is formed when atomic orbitals ______ and a pair of electrons is ______ in the region between the atoms

(The mixing of atomic orbitals to produce ____ orbitals)

A

Covalent

Overlap

Localized

Hybrid

63
Q

Steps for using Valence Bond Theory

A

1) determine # of required hybrid orbitals

-look at # of effective pairs around central atom

2) determine hybrid orbital

-write condensed e-configuration of central atom
-look at last two energy levels to see which orbitals mix
-write hybrid orbital(superscript shows HOW MANY orbitals you took from that energy level)

64
Q

What is a sigma bond between

A

Anything with p

65
Q

What is a pi bond between

A

Only p-p

66
Q

A sigma bond is the result of what kind of overlap?

Where is it electron density?

A

End-to-end overlap of orbitals

Has electron density along the axis of the bond

67
Q

A pi bond is the result of what kind of overlap?

Where is it electron density?

A

Side-to-side overlap of orbitals

Has electron density BOTH above and below the axis of the bond

68
Q

What is lattice energy

A

Energy released when anions and cations come together

69
Q

Is bond formation and bond breaking exo or endothermic

A

Formation= exothermic

Breaking= endothermic

70
Q

Bond strength is related to its ____ and ____

A

Length and energy

71
Q

What does triangle H stand for

A

Enthalpy change

72
Q

The shorter the bond, the ____ it is, therefore the ____ the bond energy

(And why)

A

Stronger

Higher

(Higher force of attraction)

73
Q

Multiple bonds are STRONGER and have HIGHER bond energies why?

A

Because they’re shorter than single bonds

74
Q

Do multiple or single bonds require more energy to break and why

A

Multiple bonds because they bring the atoms closer together

75
Q

Molecular Orbital Theory: electrons are found in molecular orbitals which represent the _____ of electrons over the ____ molecule

(Crest molecular orbitals that contain ____ the electrons)

A

Delocalization

Entire

All

76
Q

When writing condensed electron configuration of an ion (so has a charge) which orbital do you TAKE AWAY electrons from

(And give an example)

A

Take electrons out of the HIGHEST energy level (so highest numbered orbital)

Ex) take electrons out of the 4s before the 3d

76
Q

Black line spectra: the last line after a big black block is always n= ____

A

Infinite

76
Q

Black line spectra: what nf values do these correspond to?

Ground state

first excited state

Second excited state

A

n=1

n=2

n=3

77
Q

Black line spectra: How to determine the n initial of the FIRST line

(And give an example)

A

First line always has a numerical difference of 1, so determine n final based on words give and add one

Ex) “second excite state” so n final=3
so n initial of the first line is 4

78
Q

What is a metallic hydride

A

Hydrogen bonded to a TRANSITION METAL

79
Q

What is an ionic hydride

A

Hydrogen bonded to an S-BLOCK element

80
Q

What is a covalent hydride

A

Hydrogen bonded to a NON-METAL

81
Q

When counting for condensed electron configuration do you INCLUDE the element that you want in you counting

A

YES

82
Q

How to determine bond order in MO’s

A

Bond order=
(# of e on BMO- # of e on ABMO)/2

83
Q

What property does stability correspond to and what does this mean

A

Bond order

Fractional bond order ISN’T stable

84
Q

of molecular orbitals formed is always ____ to the # of atomic orbitals that are combined

A

Equal

85
Q

The combination of ____ atomic orbitals gives one BMO and ___ ABMO

A

2

1

86
Q

Bond order is a measure of ____ ____

A

Bond strength

87
Q

What happens if bond order is 0

A

No bond exist, so atom isn’t formed

88
Q

Trend in bond length:

Bond length increases= ____ bond = _____ BO

A

Weaker

Smaller

89
Q

3 reasons why hydrogen is different from other elements of group 1

A

1) is a non metal

2) forms covalent bonds with non metals

3) forks ionic hydrides with metals and metallic hydrides with transition metals

90
Q

What are H3O+ and OH- called

A

Hydronium and hydroxyl

91
Q

What is an Arrhenius acid

(And what must it contain)

A

Compound that increases the concentration of H3O+ in solution

Must contain an ionizable H in the structure

92
Q

What is an Arrhenius base

(And what must it contain)

A

Compound that increases the concentration of OH- ions in solution

Must contain an ionizable OH on the structure

93
Q

What is a BL acid

A

Compound that can donate a proton (H+)

94
Q

What is a BL base

A

A proton acceptor

95
Q

What is a Lewis acid

(And what do they either have)

A

Compound that accepts an electron pair

Either have:

1) a polarized bond to hydrogen, so they lose a proton, H+

2) have empty orbitals into which they can accept electrons

96
Q

What is a Lewis base to

A

Has atom(s) with non bonding electrons (lone pairs) which they can donate

97
Q

A strong acid in water will ionize _______

A weak acid in water will ionize ______ (remember arrows)

A

Completely

Partially

98
Q

HOW MANY VALENCE ELECTRONS DOES HYDROGEN HAVE when drawing lewis structures

A

1

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