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chemistry > Structure and bonding > Flashcards

Structure and bonding Flashcards

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1
Q

Electrostatic forces

A

Force between the oppositely charged particles
which causes covalent and ionic bonds to be strong.

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2
Q

Intermolecular forces

A

Force between each simple covalent molecule. When broken, doesn’t break the bonds but causes a change in state.

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3
Q

Ionic compounds - what melting + boiling points and why?

A

High
Because the oppositely charged ions are held together by strong electrostatic forces
It takes a lot of energy to break these forces between ions
So it has a high melting point so solid at room temperature

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4
Q

Ionic compounds - do they conduct electricity and why?

A

Only when dissolved in water or molten
Because it has a giant ionic lattice structure
When it is solid the ions are in a fixed place and cannot move
Therefore they cannot carry a charge
When melted or dissolved the ions are free to move
So they can therefore carry a charge

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5
Q

Why are covalent bonds strong?

A

Both the nucleus in each atoms (positive) is strongly attracted to the shared electrons in the outer shell (negative).
So electrostatic attraction

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6
Q

Simple molecules - what melting and boiling points and why?

A

Low
Because it has weak intermolecular forces
Little energy is needed to overcome these weak forces
So it has a low boiling point and is a gas at room temperature

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7
Q

Simple molecules - do they conduct electricity and why?

A

No
It has no delocalised electrons or ions
So has no particles to carry a charge

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8
Q

What is a giant covalent structure?

A

Millions of atoms joined together by covalent bonds that are arranged in a lattice shape.

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9
Q

Do giant covalent structures have high or low boiling/melting points? Why?

A

Very high
Because it has a giant covalent structure
With millions of covalent bonds between the many atoms
So a lot of energy is needed to overcome their strong covalent bonds
So has high melting/boiling point and a solid at room temperature

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10
Q

Metallic bonding

A

Bonding in metal elements due to sea of delocalised electrons moving
And the electrostatic attraction between the electrons and positive metal ions

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11
Q

Do metal bonds conduct electricity?

A

Yes
They have a giant metallic lattice structure
So has delocalised electrons
That can move through a structure carrying a charge

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12
Q

Do metal bonds have high or low melting/boiling points?

A

High
Have a giant metallic lattice structure
The positive metal ions are held together by delocalised electrons
This strong electrostatic attraction takes a lot of energy to overcome and pull the ions apart
So have a high melting point

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13
Q

Are metal bonds soft?

A

Yes, because the metal atoms are arranged in layers so when a force is applied they slide over each other

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14
Q

Alloy

A

Mixture of 2 or more elements, where at least one is a metal. Usually 2 metals in order to increase hardness of pure metals.

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15
Q

Why are alloys harder than pure metals?

A

Many different sized atoms due to multiple elements so greater force needed to make layers slide over each other
The layers are DISTORTED

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16
Q

What bonding forms giant structures?

A

All 3: giant ionic lattices, giant covalent structures and giant metallic structures

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17
Q

Polymer

A

A large molecule made up of many small units (monomers)

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18
Q

Are the bonds between atoms in a polymer weak or strong?

A

Strong because it’s joined by covalent bonds which are strong

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19
Q

What holds ionic compounds together?

A

Electrostatic forces

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20
Q

How can metals and graphite conduct electricity?

A

Because they both have delocalised electrons that can conduct heat

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21
Q

Fullerene

A

Molecules of carbon atoms with hollow shapes
Normally made out of hexagonal rings

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22
Q

Are ionic compounds molecules?

A

No because a molecules is 2 or more atoms held together by COVALENT bonds

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23
Q

What forms graphite?

A

Carbon atom covalently bonded to 3 other carbon atoms
In hexagonal rings
Then large rings are in layers with no bonds between

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24
Q

Properties of graphite

A

High melting and boiling point
Soft and slippery
Good conductor of heat and elec

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25
Q

Why does graphite have high melting and boiling points?

A

It takes a lot of energy to break covalent bonds

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26
Q

Why is graphite slippery?

A

The hexagonal rings the carbon atoms are in are in layers
No covalent bonds between the layers = they can slide
Therefore it’s slippery

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27
Q

Why is graphite good conductor of heat and elec?

A

Because the C atoms form 3 other singular covalent bonds
So has a spare electron that isn’t shared as carbon has 4 electrons in outer shell therefore there is one free electron
Which is released in the outer shell
To be delocalised and move between layers and conduct electricity

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28
Q

What makes up diamond?

A

4 carbon atoms covalently bonded with 4 other carbons
Millions of these

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29
Q

Properties of diamond

A

High melting and boiling point
Cannot conduct electricity

30
Q

Why does diamond have high melting and boiling points?

A

Because it contains millions of carbon atoms covalently bonded
To melt requires breaking these millions of bonds
Which require a lot of energy

31
Q

Why does diamond not conduct electricity?

A

It has no free electrons to carry electrical charge

32
Q

What makes up silicon dioxide?

A

Silicon atom bonded covalently with 4 oxygen atoms
Millions of these

33
Q

Properties of silicon dioxide

A

Very high melting and boiling point

34
Q

Why does silicon dioxide have high melting and boiling point?

A

Because it contains many covalent bonds that require a lot of energy to break

35
Q

What makes up graphene?

A

Single layer of graphite
Aka a layer of hexagonal rings of carbon atoms covalently bonded to 3 other carbon atoms

36
Q

Properties of graphene

A

Only 1 atom thick
Good conductor of elec
Extremely strong

37
Q

Why is graphene a good conductor of elec?

A

Because it is a giant covalent structure
Each carbon atom forms 3 bonds
This means there is 1 delocalised electron per carbon atom
These delocalised electrons can move through the structure carrying a charge

38
Q

Why is graphene strong?

A

Not in layers so can’t Slide Over each other

39
Q

Fullerenes

A

Molecules of carbon atoms with hollow shapes

40
Q

Buckminsterfullerene

A

Contains 60 carbon atoms in hollow sphere
Can have a ring of 5 carbon atoms or 6 carbon atoms
Each bonded 3 times

41
Q

Fullerenes use

A

Delivery drugs into the body
Lubricants to reduce friction
Catalysts

42
Q

Carbon nanotubes

A

Carbon rings forming a long hollow cylinder

43
Q

Carbon nanotubes properties

A

Have high tensile strength
Conduct electricity and heat

44
Q

Carbon nanotubes uses

A

Reinforce materials

45
Q

Polymer vs monomer

A

The monomer has a double carbon to carbon covalent bond
Whereas the polymer has singular carbon to carbon bonds

46
Q

Repeating unit

A

Short hand way of writing a polymer
Has brackets around one section of the polymer (with its single carbon to carbon bond) and an n outside it
The bonds extend outside the bracket

47
Q

Why are polymers solid at room temperature?

A

Because the intermolecular forces of attraction between polymer molecules are quite strong
Since they are arranged in layers
It takes a lot of energy to break these many forces

48
Q

Micrometer

A

1x10⁻⁶ of a Metre

49
Q

Nanometre

A

1x10⁻⁹ of a metre

50
Q

Coarse particles

A

Dust
Have a diameter of between 2500 to 10000 nanometres
Contain thousands of atoms

51
Q

Coarse particles name

A

PM ₁₀

52
Q

Fine particles name

A

PM2.5

53
Q

Fine particles size

A

100 to 2500 nanometres
Contain several thousand atoms

54
Q

Nano particles

A

Diameter between 1-100 nanometre
Only contain a few hundred atoms

55
Q

Relationship between particles size and surface area:volume ratio

A

As it decreases by 10 times
The surface area to volume ratio increases 10 times
Aka the difference gets bigger between surface area and volume increases by x10

56
Q

Nano particles surface area to volume ratio

A

Huge because they are the smallest
So have a very large surface area compared to its volume
So we don’t need many of them when using it

57
Q

Uses of nano particles

A

Medicine
Suncream
Cosmetics
Deodorant
Electronics
Catalysts

58
Q

Risks of nano particles

A

Can be absorbed and enter our cells

59
Q

Dot and cross diagram

A

Using dots and crosses to represent the electrons in different atoms when bonding

60
Q

Advantage of dot and cross diagrams

A

Clear which electrons belong to which atom and where they are coming from

61
Q

Stick diagram

A

Using one line to represent a covalent bond

62
Q

Stick diagram disadvantage

A

Don’t tell us which electron came from where/which atom
Don’t tell us about outer electrons not in a bond
Don’t tell us shape of molecule

63
Q

3d stick diagram

A

Uses dotted lines and thicker lines to show which bonds are closer and what direction

64
Q

3d stick diagram advantages

A

Shows shape of molecule

65
Q

Ball and stick diagram

A

Used for giant structures
Where balls are ions and the sticks are bonds

66
Q

Advantage of ball and stick diagram

A

Shows ions clearly in 3 dimensions

67
Q

Ball and stick diagram disadvantage

A

Shows ions as widely spaced but in reality they are packed closely together
Only shows a tiny part so give inaccurate sizing

68
Q

Space filling diagram

A

Where the ions are shown as large balls in 3D with no sticks

69
Q

Advantage of space filling diagrams

A

Shows how closely ions are packed together

70
Q

Disadvantage of space filling diagram

A

Difficult to see how they’re 3D
Only shows a tiny part of the lattice = inaccurate sizing

71
Q

Disadvantage of a dot and cross diagram

A

Don’t tell us the shape of molecule

chemistry (46 decks)

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