Bonding Flashcards

1
Q

Define ion

A

a charged atom

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2
Q

Define ionic bond

A

the electrostatic force of attraction between oppositely charged ions

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3
Q

Describe the structure of an ionic structure

A

ionic bonds have a lattice structure and the ions are arranged in a regular pattern

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4
Q

Properties of ionic compounds

A
  • high melting and boiling point (strong electrostatic forces of attraction)
  • brittle (ionic crystals can split apart)
  • soluble in water (can form ion-dipole bonds)
  • conduct electricity when molten or dissolved (ions are free to move)
  • low volatility (strong ionic bonds, lot of energy required)
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5
Q

covalent bond

A

the electrostatic force of attraction between a positively charged nuclei and a pair of electrons

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6
Q

Relationship between bond length and bond strength

A

bond length decreases as there are more electron pairs involved, causing greater attractive forces between the 2 nuclei and the bond strength increases because more energy is needed to break them

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7
Q

How does electronegativity relate to the type of bond

A
  • big electronegativity difference <2 (ionic bond)
  • small electronegativity difference 1 – 2 (polar)
  • no difference in electronegativity <1 (non-polar)
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8
Q

Properties of simple covalent structures

A
  • low melting and boiling point (weak IMFs)
  • doesn’t conduct electricity (no free ions or electrons)
  • insoluble if non-polar, soluble if polar
  • high volatility (weak IMFs)
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9
Q

What affects the polarity of a molecule

A
  • the electronegativity difference
  • the symmetry of the bonds
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10
Q

What are the properties of non-polar and polar molecule

A

polar: difference in electronegativity, asymmetrical structure
non-polar: polar bonds cancel out

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11
Q

How to draw a lewis structure

A

1) count the total number of valence electrons
2) determine the central atom (furthest from F)
3)Put all the remaining valence electrons as lone pairs
4)Count the total number of valence electrons

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12
Q

Who has incomplete octets

A

Be and B

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13
Q

Who can expand their octets

A

elements of period 3 and below

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14
Q

Examples of resonance structures

A

carbonates, benzene, ozone,

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15
Q

Vesper Theory

A
  1. all electron pairs and all lone pairs arrange themselves as far apart
  2. Lone pairs repel more strongly than bonding pairs
  3. multiple bonds behave like single bonds
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16
Q

What is the structure and bond angle for 2 bonding pairs

A

linear + 180°
ex: CO2 or BeCl2

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17
Q

What is the structure + bond angle for 3 bonding pairs

A

trigonal planar + 120°
ex: BF3
bent + <120° (118°) – (1lone pair)
ex: SO2

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18
Q

What is the structure and bond angle for 4 bonding pairs

A

tetrahedral + 109.5°
ex: CH4, NH4+
trigonal pyramidal + <109.5° (1 lone pair)
ex:NH3
bent + <109.5° (2 lone pairs)
ex:H2O

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19
Q

What is the structure and bond angle for 5 bonding pairs

A

trigonal bipyramid + 90°&120°
ex:PCl5
seesaw + 90°&<120° (1 lone pair)
ex: SF4
T-shaped + 90° (2 lone pairs)
ex: ClF3
linear + <180° (3 lone pairs)
ex: I3-

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20
Q

What is a resonance structure

A

it involves (delocalised) electrons being shared between more than one bonding position

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21
Q

What are the different polyatomic ions

A

NO3-, CO3 2-, HPO4 2-, SO4 2-, PO4 3-, NH4+, OH-

22
Q

Describe the structure and properties of diamond

A
  • tetrahedral
  • each carbon atom is covalently to 4 other carbon atoms
  • very hard
  • high melting and boiling point
  • doesn’t conduct electricity
23
Q

Describe the structure of graphite

A
  • contains hexagonal layers
  • each carbon is covalently bonded to 3 other carbons
  • acts as a great lubricant
  • weak intermolecular forces in between the hexagonal sheets
  • conducts electricity
  • high melting and boiling point
24
Q

Describe the structure of Buckminsterfullerene

A
  • contains 60 carbons
  • each carbon is covalently bonded to 3 others
  • it is a semi-conductor of electricity
  • spherical shape with atoms arranged in hexagons
  • high melting and boiling point
25
Q

Describe the structure of graphene

A
  • a single layer of carbon atoms that are bonded together in a repeating pattern of hexagons
  • each carbon atom is covalently bonded to 3 others
  • conducts electricity
  • high melting and boiling point
26
Q

Describe the structure of silicon dioxide

A
  • tetrahedral
  • each silicon is covalently bonded to 4 oxygen atoms
  • each oxygen atoms is bonded to 2 silicon atoms
  • doesn’t conduct electricity
  • high melting and boiling point
27
Q

What are the 3 types of intermolecular forces

A
  • LDFs
  • dipole-dipoles forces
  • hydrogen bonding
28
Q

What factors affect the strength of LDFs

A
  • the surface area (the size of the molecule)
  • the number of electrons (down a group)
29
Q

Characteristics of LDFs

A
  • exists between each atom and molecule
  • weakest intermolecular force
30
Q

Characteristics of dipole-dipole forces

A
  • exists between molecules with a region of negativity and positivity
  • higher melting and boiling point than LDFs
31
Q

What factors affect the strength of dipole-dipole forces

A
  • the difference in electronegativity
32
Q

Characteristics of Hydrogen bonding

A
  • forms between H and F,O,N
  • highest melting and boiling point between the 3
33
Q

Define metallic bond

A

the electrostatic force of attraction between metal positive ions and the sea of delocalised electrons

34
Q

Properties of metallic bonding

A
  • high melting and boiling point (strong forces of attraction)
  • conducts electricity (delocalised electrons)
  • malleable and ductile (layers can slide over each other)
35
Q

Factors that affect the strength of metallic bond

A
  • the charge of the ion (the greater the charge, the greater the number of delocalised electrons, so greater forces of attraction)
  • the ionic radius (the smaller the ionic radius, the greater the attraction with delocalised electrons)
36
Q

Trends in melting points across a period for metals

A

it increases
- increase in delocalised electrons
- greater ionic charges
- smaller ionic radius

37
Q

Trends in melting points down a group for metals

A

it decreases
- greater ionic radius, so weaker forces of attractions

38
Q

Define alloys

A

the mixture of metals

39
Q

Properties of alloys

A
  • higher melting and boiling points
  • higher resistance to corrosion
  • stronger and harder
40
Q

Why are alloys stronger the metals

A

alloys consist of different size atoms, which distorts the regular arrangement and makes it harder for the layers to slide over each other so more energy is needed

41
Q

How are sigma bonds formed

A

the direct head-on overlap of orbitals (s-s, s-p), resulting in electron density concentrated between the nuclei of the bonding atom

42
Q

How are pi bonds formed

A

the sideways overlap of p orbitals, resulting in an electron density above and below the plane of nuclei of the bonding atom

43
Q

What is the formula for formal charge

A

V - 1/2 (B + L)
V= n° of valence electrons
B= n° of bonding electrons
L= n° of non-bonding electrons

44
Q

What does the formula charge tell us

A

to find the most stable lewis structure
- closest value of 0
- most electronegativity atom must have the negative charge
(calculate for each element)

45
Q

What is the relationship between hybridisation and electron domain

A

sp = linear
sp2 = trigonal planar
sp3 = tetrahedral

46
Q

What are the 2 main compounds involved in catalytic depletion

A

nitrogen oxides and CFCs

47
Q

Describe catalytic depletion

A

1) nitrogen monoxide reacts with ozone to form nitrogen dioxide radical and oxygen molecule
2) The nitrogen dioxide radical reacts with with oxygen radical and forms nitrogen monoxide radical and oxygen
3) same thing for chlorine

48
Q

Why does oxygen require less energy than ozone

A

oxygen has a bond order of 2, more energy required
ozone has a bond order of 1.5, less energy required

49
Q

What are the species that will form dative coordinate covalent bonds

A

H20 (H30+), NH3 (NH4+), Cl-, CN-, OH-

50
Q

Rank the bond lengths according to strengths

A

single = weakest
double = weak
triple = strongest