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GCSE Chemistry COPY > C3.7 - Giant covalent structures > Flashcards

C3.7 - Giant covalent structures Flashcards

1
Q

What is diamond a form of?

A

Diamond is a form of the element carbon

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2
Q

What is the hardest known natural substance?

A

The hardest known natural substance is diamond

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3
Q

How can artificial diamonds be made?

A

Artificial diamonds can be made by heating pure carbon to very high temperatures under enormous pressures

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4
Q

Artificial diamonds can be made by heating pure carbon to very high temperatures under enormous pressures.
What happens to ‘industrial diamonds’ made like this?

A

‘Industrial diamonds’ made like this are embedded in the drills used by oil companies

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5
Q

Artificial diamonds can be made by heating pure carbon to very high temperatures under enormous pressures.
‘Industrial diamonds’ made like this are embedded in the drills used by oil companies.
What do the oil companies have to do?

A

The oil companies have to drill through layers of rock to get to the crude oil deep underground

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6
Q

Giant covalent structures

A

Giant covalent structures are huge 3D networks of covalently bonded atoms

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7
Q

Why do diamonds make beautiful jewellery?

A

Diamonds make beautiful jewellery, because they are:

  1. Hard
  2. Shiny
  3. Transparent
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8
Q

How are giant covalent structures held together?

A

Giant covalent structures are held together by covalent bonds throughout the lattice

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9
Q

As well as diamond, what also have giant covalent structures?

A

As well as diamond:
1. Graphite
2. Silicon dioxide (silica)
also have giant covalent structures

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10
Q

What does having a giant covalent structure give substances?

A

Having a giant covalent structure gives substances some very special properties, they:

  1. Have very high melting points and boiling points
  2. Are insoluble in water
  3. Are hard and do not conduct electricity, apart from graphite
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11
Q

Having a giant covalent structure gives substances some very special properties, they have very high melting points and boiling points, are insoluble in water and are hard and do not conduct electricity, apart from graphite.
Example

A

For example, diamond:

  1. Is exceptionally hard
  2. Has a boiling point of 4827 degrees Celsius
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12
Q

In diamond, each carbon atom does what?

A

In diamond, each carbon atom forms 4 strong covalent bonds

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13
Q

What is carbon not always found as?

A

Carbon is not always found as diamonds

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14
Q

Carbon is not always found as diamonds.

What is another form of carbon?

A

Another form of carbon is graphite

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15
Q

In graphite, the carbon atoms are only what?

A

In graphite, the carbon atoms are only bonded to 3 other carbon atoms

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16
Q

In graphite, the carbon atoms are only bonded to 3 other carbon atoms.
They form hexagons, which are arranged in giant layers.
What is there between the layers?

A

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

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17
Q

In graphite, the carbon atoms are only bonded to 3 other carbon atoms.
They form hexagons, which are arranged in giant layers.
There no covalent bonds between the layers, only weak intermolecular forces, so what can happen?

A

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

18
Q

In graphite, the carbon atoms are only bonded to 3 other carbon atoms.
They form hexagons, which are arranged in giant layers.
There no covalent bonds between the layers, only weak intermolecular forces, so the layers can slide over each other quite easily.
What does this make graphite?

A

This makes graphite a soft material that feels slippery to the touch

19
Q

What do carbon atoms have in their outer shell available for bonding?

A

Carbon atoms have 4 electrons in their outer shell available for bonding

20
Q

Carbon atoms have 4 electrons in their outer shell available for bonding.
What does this leave in graphite?

A

This leaves one spare outer electron on each carbon atom in graphite

21
Q

Carbon atoms have 4 electrons in their outer shell available for bonding.
This leaves one spare outer electron on each carbon atom in graphite.
What can these mobile electrons do?

A

These mobile electrons can move freely along the layers of carbon atoms

22
Q

What are the mobile electrons found in graphite called?

A

The mobile electrons found in graphite are called delocalised electrons

23
Q

Delocalised electron

A

A delocalised electron is a bonding electron that is no longer associated with any one particular atom

24
Q

Carbon atoms have 4 electrons in their outer shell available for bonding.
This leaves one spare outer electron on each carbon atom in graphite.
These mobile electrons can move freely along the layers of carbon atoms.
The mobile electrons found in graphite are called delocalised electrons.
They no longer what?

A

The delocalised electrons no longer belong to any one particular carbon atom

25
Q

What allows graphite to conduct electricity?

A

The delocalised electrons allow graphite to conduct electricity

26
Q

The delocalised electrons allow graphite to conduct electricity.
What will the electrons do, when put into an electrical circuit?

A

When put into an electrical circuit, the electrons will drift away from:

  1. The negative terminal of a battery
  2. Towards its positive terminal
27
Q

What can diamond and other covalently-bonded substances not do?

A
  1. Diamond
  2. Other covalently-bonded substances
    cannot conduct electricity
28
Q

Why can diamond other covalently-bonded substances not conduct electricity?

A
  1. Diamond
  2. Other covalently-bonded substances
    cannot conduct electricity, because their atoms have no free electrons
29
Q

What is graphite excellent at?

A

Graphite is an excellent conductor of thermal energy

30
Q

Why is graphite an excellent conductor of thermal energy?

A

Graphite is an excellent conductor of thermal energy, because as more energy is transferred to the delocalised electrons, they:

  1. Move around faster
  2. Rapidly transfer the energy along the layers in the graphite
31
Q

What happens when you write with a pencil?

A

When you write with a pencil, some layers of carbon atoms from the graphite:

  1. Slide off the ‘lead’
  2. Are left on the paper
32
Q

Diamond is a form of the element carbon, the same element contained in what?

A

Diamond is a form of the element carbon, the same element contained in pencil leads

33
Q

Many covalently bonded substances are made up of individual molecules.
However, some substances, such as diamond, form very different structures.
These do not have what?

A

These do not have relatively small numbers of atoms arranged in simple molecules

34
Q

Many covalently bonded substances are made up of individual molecules.
However, some substances, such as diamond, form very different structures.
These do not have relatively small numbers of atoms arranged in simple molecules.
They form what?

A

They form huge networks of atoms held together by strong covalent bonds in giant covalent structures

35
Q

In diamond, each carbon atom forms 4 strong covalent bonds, arranged in a what?

A

In diamond, each carbon atom forms 4 strong covalent bonds, arranged in a perfectly symmetrical giant lattice

36
Q

Carbon is not always found as diamonds.

Another form of carbon is graphite, the form of carbon used in what?

A

Another form of carbon is graphite, the form of carbon used in pencil lead

37
Q

In graphite, the carbon atoms are only bonded to 3 other carbon atoms.
They form what?

A

The carbon atoms form hexagons

38
Q

In graphite, the carbon atoms are only bonded to 3 other carbon atoms.
The carbon atoms form hexagons, which are what?

A

The carbon atoms form hexagons, which are arranged in giant layers

39
Q

Carbon atoms have 4 electrons in their outer shell available for bonding.
This leaves one spare outer electron on each carbon atom in graphite.
These mobile electrons can move freely along the layers of carbon atoms.
The mobile electrons found in graphite are called delocalised electrons.
The delocalised electrons no longer belong to any 1
one particular carbon atom.
They behave rather like what?

A

The delocalised electrons behave rather like the electrons in a metallic structure

40
Q

Diamond and other covalently-bonded substances cannot conduct electricity, because their atoms have no free electrons, because what?

A
  1. Diamond
  2. Other covalently-bonded substances
    cannot conduct electricity, because their atoms have no free electrons, because all their outer shell electrons are involved in covalent bonding

GCSE Chemistry COPY (70 decks)

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