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A Level Chemistry AQA > Bonding > Flashcards

Bonding Flashcards

Chap 3

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1
Q

3 types of bonding in the periodic table

A

Simple covalent (most)
Giant covalent (C & Si)
Giant metallic (most)

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2
Q

How many ionic metals are involved in metallic bonding?

A

1

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3
Q

What metal ions don’t form noble gas structures when ionic bonding?

A

Transition metals
Metals after transition metals

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4
Q

True or false: all negative ions aim to have noble gas structures

A

True

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5
Q

What determines how many electrons are transferred for cations of transition metals and the metals after transition metals (who are not trying to achieve noble gas structures)?

A

Ionisation energies

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6
Q

True or false: all non metals covalently bond to create noble gas structures

A

False— some are validly stable if they make the max no. Of bonds

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7
Q

What holds covalently bonded atoms together? (3 points)

A

electrostatic attraction between
pos nuclei and
neg shared electron pairs

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8
Q

Coordinate/Dative covalent bond

A

covalent bond when both shared electrons are provided by 1 atom (and the atom accepting e- must have an incomplete outer shell)

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9
Q

What is the “lone pair” in covalent bonding? How are they used in dative covalent bonding?

A

Electrons not being used in bonding
Donor atoms will use they lone pair in a dative covalent bond (so other atom doesn’t have to give any)

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10
Q

What makes an ionic bond strong? What do these 2 things lead to?

A
  • small ionic radius (shielding comes under this)
  • big ionic charge
    greater electrostatic attraction
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11
Q

What makes a covalent bond strong? What is the strongest kind of covalent bond?

A

The shorter the bond (the more electron pairs are shared) the stronger the bond
Triple bonds

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12
Q

What makes a metallic bond strong? (2 reasons)

A

Smaller atoms (minor point) and more delocalised electrons

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13
Q

Electronegativity

A

the measure of strength of attraction for a pair of e-

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14
Q

Electronegativity trends and why:
1) Across a period
2) Down a group

A

1) increases
- nuclear charge inc
- atomic radius dec
- shielding =
2) decreases
- nuclear charge inc
- atomic radius inc
- shielding inc

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15
Q

Types of bond polarity

A

Ionic
Polar covalent (diff electronegativity)
Non polar covalent (same electronegativity)

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16
Q

True or false: tetrachloromethane is a polar molecule where the dipoles don’t cancel out

A

False- they do cancel out as the neg chlorine cancel out the pos carbon in the middle

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17
Q

Bond dipole moment

A

A measurement of the strength and direction of the polarity in a bond (bigger electronegativity=bigger BDM)

18
Q

What is VSEPR? What is it used for?

A
  • the theory that e- pairs on the outer shell repel each other
  • predict the geometry of a molecule
19
Q

Do bonding or non bonding pairs cause a bigger repulsion? By how much?

A

Non bonding pairs
2.5 degrees

20
Q

Match the number of BONDING pairs to the correct shape:
2
3
4
5
6

A

Linear
Trigonal planar
Tetrahedral
Trigonal bipyramidal
Octahedral

21
Q

3 types of IMF (weakest to strongest)

A

Van der Waals
Permanent dipole-dipole attractions
Hydrogen bonds

22
Q

Why are the 3 IMF weak/strong?

A
  • Van der waals only induce temporary dipoles due to rapid movement of e-
  • whereas dipole-dipole is permanent
  • and hydrogen bonds cause a high charge density
23
Q

What molecules do the 3 IMF occur in?

A
  • Van der waals: ALL
  • Permanent d-d: polar MOLECULES only
  • Hydrogen bonds: any molecule where H BONDS to N, O or F
24
Q

What factors, other than IMF, affect boiling points?

A
  • Chain lengths of alkanes (longer=more IMF=higher BP)
  • Branched alkanes (more branches=less packing=lower BP)
25
Q

Why does ice float? (3)

A
  • Ice is a tetrahedron (each central water molecule is hydrogen bonded to 4 others)
  • so molecules pack less closely together than in liquid
  • so the volume is larger than the liquid making it
26
Q

What is the trend down a group of hydrides (basically H bonded to every group x atom) for BP? Why?

A

INCREASE
due to increase in shells and electrons so increase in VDWs

27
Q

Why do bigger ions have stronger van der waals? (2)

A

Bc they have more e-
so more opportunity for temporary dipoles to be induced

28
Q

Why is the BP of H20 so much higher than HF and NH3, despite all having hydrogen bonds?

A

H20 has 2 lone pairs, others have 1

29
Q

Bond angle of linear shape?

A

180

30
Q

Bond angle of V-shaped?

A

(109.5-2(2.5)= 109-5=) 104.5

31
Q

Bond angle of trigonal planar?

A

120

32
Q

Bond angle of trigonal pyramidal?

A

(109.5-2.5=) 107

33
Q

Bond angle of tetrahedral?

A

109.5

34
Q

Bond angle of trigonal bipyramidal?

A

120 (in the ring)
AND 90 (between ring + vertical bonds)

35
Q

Bond angle of octahedral?

A

90

36
Q

Bond angle of square planar?

A

90

37
Q

True or false- the bond angles of shape molecules also apply to lone pairs

A

False- these bond angles are only between bonding pairs, not bonding and lone, or just lone pairs

38
Q

When is the e- geometry the same as the molecule geometry? When is it not?

A
  • When there are no lone pairs
  • When there ARE lone pairs
39
Q

Match the formulas to ELECTRON and MOLECULE geometry:
AX2E
AX2E2
AX2E3
AX3E
AX3E2
AX4E
AX4E2
AX5E

A
  • trigonal planar: v-shaped
  • tetrahedron: v-shaped
  • trigonal bipyramidal: linear
  • tetrahedron: trigonal pyramidal
  • trigonal bipyramidal: T-shaped
  • trigonal bipyramidal: seesaw/ distorted tetrahedron
  • octahedral: square planar
  • octahedral: square pyramidal
40
Q

Why do molecules take on these shapes?

A

Bc electron pairs repel each other away as far as possible

A Level Chemistry AQA (6 decks)

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