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Bonding & Structure Flashcards

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1
Q

Bonding & Structure: Intermolecular Forces

What are the Chemical Bonds?

A
  • Ionic
  • Covalent
  • Dative Covalent (co-ordinate)
  • Metallic
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2
Q

Bonding & Structure: Intermolecular Forces

What are Ions?

A

Atoms that gain or lose electrons

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3
Q

Bonding & Structure: Ionic Bonding

What is Ionic Bonding?

A

The electrostatic attraction between oppositely charged ions

Formed when atoms lose or gain electrons

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4
Q

Bonding & Structure: Ionic Bonding

What 2 things affect the strength of an Ionic Bond?

A
  • Ionic Charges
  • Ionic Radii
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5
Q

Bonding & Structure: Ionic Bonding

What’s the relationship between charge & an Ionic Bond?

A

The greater the charge, the stronger the ionic bond
↳ higher the mp/bp

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6
Q

Bonding & Structure: Ionic Bonding

What’s the relationship between radii & an Ionic Bond?

A

Smaller ions can pack closer together than larger ions : have a stronger ionic bond
↳ higher the mp/bp

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7
Q

Bonding & Structure: Intermolecular Forces

What does the size of an Ion depend on?

A
  • Electron shell
  • Atomic number
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8
Q

Bonding & Structure: Intermolecular Forces

What happens to the Ionic Radius as u go Down a group?

(they have the same charge but..)

A

INCREASES
* atomic number increases
↳ extra electron shells are added

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9
Q

Bonding & Structure: Intermolecular Forces

What happens to the Ionic Radius of a set of isoelectric ions?

A

DECREASES
* atomic number increases
↳ proton number increases : electrons are attracted to nucleus, pulling them in

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10
Q

Bonding & Structure: Intermolecular Forces

What do Ionic Compounds form?

A

Giant Ionic Lattices

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11
Q

Bonding & Structure: Intermolecular Forces

Why are Giant Ionic Lattices formed?

A

Each ion is electrostatically attracted in all directions to ions of opposite charge

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12
Q

Bonding & Structure: Intermolecular Forces

Why are Giant Ionic Lattices described as Giant?

A

They’re made up of the same repeated basic unit

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13
Q

Bonding & Structure: Intermolecular Forces

Why do Ionic Compounds have a High mp?

A

Lots of heat is needed to overcome strong electrostatic attractions

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14
Q

Bonding & Structure: Intermolecular Forces

Why are Ionic Compounds very brittle?

A

Solid at room temp & pressure : any dislocation leads to the layers moving & splitting

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15
Q

Bonding & Structure: Intermolecular Forces

Why don’t Ionic Compounds conduct Electricity?

A

Ions aren’t delocalised ions are held strongly in the lattice

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16
Q

Bonding & Structure: Intermolecular Forces

Why do Ionic Compounds only conduct Electricity when molten?

A

The ions become mobile, they’re delocalised so they can carry a charge

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17
Q

Bonding & Structure: Intermolecular Forces

Why are Ionic Compounds soluble in water but not non-polar solvents?

A

Their particles are charged

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18
Q

Bonding & Structure: LAB

What happens when u electrolyse Copper (II) Chromate (VI)? [green]

A

Filter paper turns:
* BLUE at Cathode
* YELLOW at Anode

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19
Q

Bonding & Structure: LAB

Why does this colour change occur?

A
  • Positive ions move to Cathode
  • Negative ions move to Anode
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20
Q

Bonding & Structure: Intermolecular Forces

What is Covalent Bonding?

A

Electrostatic attraction between shared electrons & nuclei

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21
Q

Bonding & Structure: Intermolecular Forces

What does Covalent Bonding usually happen between?

A

Non-metals

Nv2 has a triple bond

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22
Q

Bonding & Structure: Intermolecular Forces

What are the positive nuclei attarcted to in a Covalent Bond?

A

Where the shared electrons are

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23
Q

Bonding & Structure: Intermolecular Forces

How is a force of repulsion formed?

A
  • 2 positive nuclei repel each other
  • electrons repel each other
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24
Q

Bonding & Structure: Intermolecular Forces

Why is a Bond Length needed?

A

To maintain a covalent bond

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25
Q

Bonding & Structure: Intermolecular Forces

What is Bond Length?

A

Distance between the nuclei
↳ where attractive & repulsive forces balance each other

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26
Q

Bonding & Structure: Intermolecular Forces

Whats the relationship between Bond Length & Bond Strength?

A

Inversely proportional

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27
Q

Bonding & Structure: Intermolecular Forces

Why’s the relationship between Bond Length & Bond Strentgh this way?

A

More electrons in a bond : stronger attraction between atoms
↳ higher the Bond Enthalpy & shorter the Bond Length

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28
Q

Bonding & Structure: Intermolecular Forces

Why’s the Mp/Bp in Covalent Bonding low?

A

Intermolecular forces are broken NOT covalent bonds

29
Q

Bonding & Structure: Intermolecular Forces

Why don’t Covalent Bonds conduct electricity?

A

Atoms are held in place

30
Q

Bonding & Structure: Intermolecular Forces

Are Covalent Bonds soluble in water?

A

Depends on whether it can form H bonds

31
Q

Bonding & Structure: Intermolecular Forces

Whats a Dative Covalent (Co-ordinate) Bond?

A

Both electrons are provided by the same atom

32
Q

Bonding & Structure: Intermolecular Forces

What’s a Reduced Octet?

A

Molecule stable without a full outer shell

33
Q

Bonding & Structure: Intermolecular Forces

What’s an example of a Stable Covalent Compound?

(Reduced Octet)

A

AlCl3

34
Q

Bonding & Structure: Intermolecular Forces

What happens when 2 AlCl3 combine?

A

One Cl in each of the 2 AlCLv3 molecules donates a lone pair to the Al on the other molecule, forming 2 dative covalent bonds

This gives Al a full outer shell

35
Q

Bonding & Structure: Intermolecular Forces

What is Metallic Bonding?

S-block/D-block

A

Involves a lattice of positive ions sorrounded by delocalised electrons

36
Q

Metallic Bond

S-block/D-block

A

Mobile electron cloud allows the conduction of electricity

37
Q

Metallic

Properties

S-block/D-block

A
  • Mp = HIGH
    ↳Hard to seperate positive ions & delocalised electrons
  • Strength = HARD
    ↳
  • Solubility = INSOLUBLE
    ↳
  • Electricity = YES
    ↳ Already has delocalised electrons
  • Malleable & Ductile
    ↳ No real bonds holding the metal ions together, the layers are separated by electrons
38
Q

Ease of separation of ions

Depends on…

A
  1. Electron density of the cloud
  2. Ionic/Atomic size
39
Q

Ease of separation of ions

Instance 1)

A
  • Charge
  • Atomic Radius
40
Q

Ease of separation of ions

Instance 2)

A
  • Atomic Radius
    ↓
    -larger atom
    ↳ more QL = more electrons
    -electron in outershell is FURTHER AWAY
    ↳ easier to lose
41
Q

Metals have Giant Structures too

Metals exist as giant metallic lattice structures.

A

Electrons in the outermost shell of the metal are delocalised.

The positive metal ions are electrostatically attracted to the negative delocalised electrons

Higher Charge of cathine = Smaller the Cathine = Stronger the Metallic Bond

42
Q

Giant Covalent & Metallic Structures

A

Diamond
* 4 carbons TETRAHEDRALLY bonded

Silicon Dioxide SiOv2
* Oxygen atoms situated between each silicon atom

43
Q

Other Giant Covalent & Metallic Structures

A

Graphite
* Each carbon is bonded to 3 other carbon atoms
* 4th carbon is delocalised → can conduct electricity

Graphene
* A thin layer of graphite
* Can conduct electricity
* Strong
* Light

44
Q

Giant Covalent & Metallic Structures

Properties

A
  • Mp = HIGH
    ↳ A lot of heat to break
  • Strength = EXTREMELY HARD
    ↳ Strong bonds
  • Thermal Conductor = GOOD
    ↳ They vibrate
  • Solubility = INSOLUBLE
    ↳ Do not contain ions
  • Electricity = CAN’T CONDUCT
    ↳ No free electrons
45
Q

All Chemical Bonds Properties

A
46
Q

Physical Attractions

Intermolecular = outside

A
  • Instantaneous/Induced (London Forces)
  • Permanent Dipole Interactions
  • Hydrogen Bonds
47
Q

Instantaneous/Induced (London Force)

A

Every compound in chem has a LONDON FORCE
* London forces take place where there are electrons

48
Q

Instantaneous/Induced (London Force)

Function

A
  • Electrons always move around an atom
    ↳ as they move, they would induce a slight charge & induce a neighbouring atom w the opposite charge
    ↓
    This attraction is short/small → this is a London Force
  • Electrons still move & break this attraction
    ↓
    everything is repeated

More electrons a compound has = higher the London Force

49
Q

Simple Molecular Lattice

A

In Iodine the molecules are held by covalent bonds to form Iv2. Between the molecules are London Forces

50
Q

Stronger London Force = Higher Mp/Bp

A
  • Less branches = higher Mp
    ↳ compound is getting longer when unbranched → meaning there are more electrons → the stronger the London Force
51
Q

Permanent Dipole

A

Somewhere in between Ionic charged & Covalent
* Occurs between molecules containing polar/ electronegative bonds

HCL & NHv3

52
Q

Permanent Dipoles occur as well as London Forces

A

Molecules that show London Forces in addition to Permanent Dipole will have a higher mp/bp than those than show only London Forces

F/O/N bonded w H = permanet dipole/polar/ → more energy needed to break

53
Q

Hydrogen Bonding

Definition

A

Occurs when hydrogen is bonded to flourine, nitrogen or oxygen

54
Q

Hydrogen Bonding

A
  • Water, ammonia & hydrogen flouride all show hydrogen bonding
  • Looking down group 7, the element becomes a permanent diapole
55
Q

Bp of Group 6 Hydrides

A
  • Hv2O is the highest as its the most electronegative
  • Hv2Se & Hv2Te are higher than Hv2S because they have a larger atomic radius, therefore there are more electrons which means a stronger LF
56
Q

Bp of Group 7

A
  • HF is the highest as its the most electronegative
  • HBr & HI are higher than HCl as they have a larger atomic radius, therefore there are more electrons which means a stronger LF

Trend is there’s a decrease in permanent dipole interactions

57
Q

Hydrogen Bonding explains Ice Floats on water

A
  • In ice,water molecules are arranged apart which wastes a lot of space
  • As ice melts, the hydrogen bonds break, the lattice breaks allowing air molecules to fill these spaces
  • This means ice is much less dense than water → so floats
58
Q

Shapes of Molecules

A
  • C-C single
  • C=C double
  • C≡C triple

Going down these bullet points the bonds become;
More rigid/strong
Shorter
Harded to break so more heat is needed as its harder to move/twist them

This is regardless the number of atoms on each other side

59
Q

Valence Shell Electron Pair Repulsion Theory

VSEPR

A

Any compound has a shape after repulsion theory

“The best arrangement is the one that minimises the repulsion”

60
Q

Shape, Angles, Examples

Linear

BeClv2

A
  • 2 Bond Pairs
  • 180° Bond Angle
61
Q

Shape, Angles, Examples

Triginal Planer

AlClv3

A
  • 3 Bond Pairs
  • 120° Bond Angle
62
Q

Shape, Angles, Examples

Tetrahedral

CHv4

A
  • 4 Bond Pairs
  • 109.5° Bond Angle
63
Q

Shape, Angles, Examples

Trigonal Bipyromidal

PClv5

A
  • 5 Bond Pairs
  • 120° & 90° Bond Angle
64
Q

Shape, Angles, Examples

Octahedral/Hexagonal

SFv6

A
  • 6 Bond Pairs
  • 90° Bond Angles
65
Q

Shape, Angles, Examples

Pyramidal

NHv3

A
  • 3 Bond Pairs
  • 107° Bond Angle
  • 1 Pair of lone electrons
66
Q

Exception

Group 2 Berylium

A

-In Group 2 Be only forms a covalent bond
↳ because its more stable w sharing electrons than donating

67
Q

Reduced Octet

Be in BeClv2 or Al in AlClv3

A

Are stable with less than 8 electrons around their central atom

68
Q

Expanded Octet

P in PClv5 or S in SFv6

A

Are stable with more than 8 electrons around their central atom

69
Q

Lone Pairs

A

Every lone pair that you introduce to a compound, you’ll decrease the bond angle by 2 1/2°
* Lone pairs repel each other
↳ pushing bond angles → bond angles are pushed inwards

Chemistry (13 decks)

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