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GCSE Chemistry > GIANT COVALENT STRUCTURES + fullerenes > Flashcards

GIANT COVALENT STRUCTURES + fullerenes Flashcards

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1
Q

Give examples of giant covalent structures

A

Examples of giant covalent structures:

Diamond
Graphite
Silicon dioxide
Graphene

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2
Q

Define allotrope

A

Allotropes are different structural forms of the same element in the same physical state

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3
Q

Examples of allotropes of carbon

A

Diamond
Graphite
Graphene
Fullerenes

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4
Q

At what state are giant covalent structures at room temperature

A

Giant covalent molecules are always SOLIDS at room temperature

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5
Q

Explain why giant covalent structures are always solids at room temperatures

A

Giant covalent molecules are always solids at room temperatures. This is because they have millions of strong covalent bonds which means that they have high melting and boiling points

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6
Q

Describe the melting and boiling points in giant covalent molecules

A

Giant covalent molecules have high melting and boiling points

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7
Q

From which element is diamond formed

A

Diamond is formed from the element CARBON

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8
Q

What must happen to melt or boil giant covalent structures

A

These bonds must be overcome (broken) to melt or boil these substances.

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9
Q

Describe the structure of the giant covalent molecule of diamond

A

In diamond, each carbon atom forms four strong covalent bonds with four other carbon atoms in a giant covalent structure.

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10
Q

State the properties of diamond

A

Diamond is very hard (and strong)
Diamond has a very high melting point and boiling point
Diamond does not conduct electricity

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11
Q

Explain why diamond cannot conduct electricity

A

Diamond cannot conduct electricity because it does not have any delocalised electrons to carry a charge through the giant covalent structure

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12
Q

Explain why diamond has a very high melting and boiling point

A

This is because diamond has a huge number of strong covalent bonds which must be broken and this takes a lot of energy.

Therefore diamond has a very high melting and boiling point

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13
Q

Explain why diamond is very hard.

A

In diamond, each carbon atom forms four strong covalent bonds with four other carbon atoms in a giant covalent structure. This makes diamond really hard

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14
Q

What is silicon dioxide also referred as

A

Silicon dioxide is sometimes called silica or sand

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15
Q

State the elements that silicon dioxide contain

A

Silicon dioxide contains the elements
Silicon and oxygen (covalently bonded together)

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16
Q

State the properties of silicon dioxide

A

Silicon dioxide has a very high melting and boiling point.

Silicon dioxide does not conduct electricity

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17
Q

Explain why silicon dioxide does not conduct electricity

A

Silicon dioxide cannot conduct electricity because there are no free electrons (delocalised electrons) to carry an electrical charge through the giant covalent structure

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18
Q

Explain why silicon dioxide has a very high melting and boiling point

A

Silicon dioxide has a very high melting and boiling point.

This is because silicon dioxide has a huge number of strong covalent bonds which must be broken and this takes a lot of energy.

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19
Q

State the uses of silicon dioxide

A

Silicon dioxide is used to make glass and concrete

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20
Q

State the molecular formula for silicon dioxide

A

Silicon dioxide - SiO2

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21
Q

From which element is graphite formed from

A

Graphite is formed from the element carbon

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22
Q

State the properties of graphite

A

Graphite has a high melting and boiling point

Graphite is soft and slippery

Graphite is an excellent conductor of both electricity and heat

Graphite is soft and brittle

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23
Q

Describe the structure of graphite

A

In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings.

There are no covalent bonds between the layers, only weak intermolecular forces

hexagonal rings - rings of six carbon atoms

24
Q

Explain why Graphite has a high melting and boiling point

A

This is because graphite has a huge number of strong covalent bonds which must be broken and this takes a lot of energy.

Therefore graphite has a very high melting and boiling point

25
Q

Explain why Graphite is soft and slippery

A

In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings.

There are no covalent bonds between the layers, only weak intermolecular forces, so the layers can slide over each other.

This makes graphite soft and slippery

26
Q

Is graphite a metal

A

Graphite is based on the element, carbon, so it is not a metal

27
Q

Explain why graphite is an excellent conductor of electricity and heat

A

Graphite has delocalised electrons which can move through the giant covalent structure and carry a charge. The delocalised electrons can also conduct thermal energy (heat)

28
Q

Explain why graphite can conduct electricity but diamond cannot

A

Graphite has hexagons of Carbon atoms arranged in layers.

Each Carbon atom forming three strong covalent bonds to its nearest neighbours, (STRUCTURE OF GRAPHITE) AS Carbon atoms have 4 electrons in it’s outer shell, this leaves one free outer electron on each carbon atom in graphite.

The delocalised drift freely along layers, and carry a charge . This enables graphite to conduct electricity.

while

In diamond, each carbon atom forms four strong covalent bonds with four other carbon atoms in a giant covalent structure. (structure of diamond)

ALL the outer shell electrons are involved in covalent bonding therefore there are no free electrons to carry electrical charge through the structure.

29
Q

Uses of graphite - link these uses to their structures

A

Graphite is used as a lubricant (in machines) - layers can slide
Graphite is used as electrodes in batteries - conducts electricity

30
Q

Explain how graphite is similar to metals

A

Graphite is similar to metals as both graphite and metals have delocalised electrons which move through their structures and carry a charge, making them both good conductors of heat and electricity

31
Q

How many atoms thick is graphene

A

Graphene is one atom thick

32
Q

Uses of graphene

A

Graphene is used in the electronics industry

33
Q

Describe the structure of graphene

A

Graphene is a single layer of graphite.

In graphene, each carbon atom forms three covalent bonds with three other carbon atoms, forming a layer of hexagonal rings.

34
Q

Describe the properties of graphene

A

Graphene is an excellent conductor of electricity

Graphene is extremely strong.

Graphene has a high melting point

35
Q

Explain why graphene has a high melting point

A

This is because graphene has a huge number of strong covalent bonds which must be broken and this takes a lot of energy.

Therefore graphene has a very high melting and boiling point

36
Q

Explain why graphene has is very strong

A

Graphene has many strong covalent bonds. This makes graphene really strong.

37
Q

Explain why graphene is an excellent conductor of electricity

A

Graphite has delocalised electrons which can move through the giant covalent structure and carry a charge.

38
Q

What is a fullerene

A

Fullerenes are molecules of carbon atoms with hollow shapes.

39
Q

Describe the structure of fullerenes

A

The structure of fullerenes is based on hexagonal rings of carbon atoms
but they may also contain rings with five or seven carbon atoms.

40
Q

What was the first fullerene to be discovered

A

The first fullerene to be discovered was Buckminsterfullerene (C60)
which has a spherical shape.

41
Q

What shape is a Buckminsterfullerene molecule?

A

Buckminsterfullerene (C60)
has a spherical shape.

SPHERICAL

42
Q

What is the chemical formula for the Buckminsterfullerene molecule

A

Buckminsterfullerene - C60

43
Q

From which element are fullerenes formed

A

Fullerenes are formed from CARBON atoms

44
Q

Uses of fullerenes

A

Uses of fullerenes

Pharmaceutical delivery

Lubricants (spherical fullerenes for lubricants)

Catalysts

Hydrogen storage

Anti-oxidants

Reduction of bacterial growth

Strengthening materials (cylindrical fullerenes for strengthening materials)

  • drug delivery (round the body)
45
Q

State the properties of buckminsterfullerene

A

Low melting and boiling point
Slippery
Soft and brittle

46
Q

Explain why buckminsterfullerene has a low boiling and melting point

A

Buckminster fullerene have a simple covalent structure

Simple covalent molecules have weak intermolecular forces. The weak intermolecular forces between the molecules do not require a lot of energy to break, therefore simple covalent molecules have low melting and boiling points.

47
Q

What type of structure is buckminsterfullerene

A

Buckminsterfullerene has a simple covalent structure

48
Q

Explain why Buckminsterfullerene can be used as a lubricant

A

Buckminsterfullerene can is slippery, it can roll over each other. This makes it good to be used as a lubricant

49
Q

What can buckminsterfullerene also be referred as

A

The other names for buckminsterfullerene

Bucky ball
Fullerene

50
Q

Buckminsterfullerene has ______ _________ atoms joined by _________ bonds

A

Buckminsterfullerene has sixty carbon atoms joined by covalent bonds.

51
Q

State a group of fullerenes

A

Carbon nanotubes - a group of fullerenes

52
Q

What are carbon nanotubes

A

Carbon nanotubes are cylindrical fullerenes with very high length to
diameter ratios. Their properties make them useful for
nanotechnology, electronics and materials.

53
Q

State the properties of carbon nantubes

A

Carbon nanotube have high tensile strength (can be stretched without breaking)

Carbon nanotubes are excellent conductors of heat and electricity.

54
Q

State the uses of carbon nanotubes

A

Carbon nanotubes are used to reinforce composite materials (for example those used in making tennis rackets) due to their high tensile strength

55
Q

Explain why carbon nanotubes are good conductors of electricity and heat

A

The bonding of the carbon atoms in carbon nanotubes is like the bonding of the carbon atoms in graphite.
This means that they have delocalised electrons which can move through the structure and carry a charge.

GCSE Chemistry (43 decks)

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