Chemistry transition work!!! Flashcards

test on second lesson

1
Q

What charge do electrons have?

A

-1

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2
Q

What charge will an ion of lithium take?

A

1+ (needs to loose on electron on outer shell)

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3
Q

What charge will an ion of beryllium take?

A

2+ (needs to loose the 2 electrons in outer shell)

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4
Q

What charge will an ion of barium take

A

2+(in group 2 so needs to loose both electrons )

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5
Q

What will an ion of fluorine take?

A

1- (7 electrons on outer shell so needs to gain one)

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6
Q

If something gains electrons what charge does it need to take?

A

a Negative charge

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7
Q

If something has lost electrons what charge will it have?

A

A positive charge

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8
Q

What charge will an ion of oxygen take?

A

2- (because is has 6 electrons on its outer shell so needs to gain two)

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9
Q

What charge will an ion of selenium take?

A

2- (group 6 so it has 6 electrons in it outer shell and needs to gain two)

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10
Q

Why do atoms transfer electrons in ionic bonding

A

So that they can have full outer shells

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11
Q

Explain in terms of electrons what occurs when lithiums bonds with fluorine

A

One electron transferred from lithium to fluorine

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12
Q

Explain in terms of electrons what occurs when magnesium bonds with oxygen

A

Two electrons transferred from magnesium to oxygen

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13
Q

Explain in terms of electrons what occurs when magnesium bonds with chlorine

A

One electron is transferred from magnesium to two different chlorine atoms

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14
Q

Explain in terms of electrons what occurs when sodium bonds with oxygen?

A

Two electrons from two different sodium atoms are transferred to an oxygen atom

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15
Q

Why do sodium ions and chlorine ions form an ionic bond?

A

There is an electrostatic force of attraction between oppositely charged ions

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16
Q

Why don’t sulphide ions and oxide ions form ionic bonds with each other?

A

Both have negative charges so would repel

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17
Q

What is the name for a substance made of billions of oppositely charged ions joined together?

A

Giant ionic lattice

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18
Q

State the melting points of ionic substances

A

High

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19
Q

Explain why ionic substances have high melting points.

A

Strong forces of attraction between oppositely charged ions require high amounts of energy to overcome

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20
Q

Will NaCI(s) conduct electricity?

A

No

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21
Q

Will NaCI (aq) conduct electricity?

A

Yes (aq stands for aqueous which means it is dissolved in water)

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22
Q

Will NaCI (I) conduct electricity?

A

Yes

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23
Q

What does molten mean

A

Melted

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24
Q

Explain why ionic compounds do not conduct electricity when solid

A

Because the ions are not free to move

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25
Q

Explain why ionic compounds conduct electricity in solution

A

Because the ions are free to move and carry charge

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26
Q

Explain why ionic compounds conduct electricity when molten

A

Because the ions are free to move and carry charge

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27
Q

What does soluble mean?

A

Dissolves in water

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28
Q

What does insoluble mean?

A

Does not dissolve in water

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29
Q

Magnesium carbonate is insoluble. What do you need to do before it will conduct electricity?

A

Melt it

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30
Q

Sodium fluoride is soluble.
Explain what the easiest way for it to conduct electricity

A

Dissolve it in water because this does not require high temperatures

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31
Q

Explain why chlorine and fluorine form covalent bonds

A

They are both non-metals

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32
Q

Complete the sentence: In covalent bonds, electrons
are

A

Shared

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33
Q

In ionic bonds, electrons
are

A

Transferred

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34
Q

What is the name given to the structure of diamond, graphite and silicon dioxide?

A

Giant covalent

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35
Q

Draw a dot and cross diagram for methane CH4

A

[draw it]

36
Q

How many bonds does each carbon have in diamond?

A

4

37
Q

Explain why diamond has a high melting point

A

It has a giant covalent structure so contains strong covalent bonds between the atoms. This requires a lot of energy to break

38
Q

Explain why most giant covalent substances do not conduct electricity

A

There are no electrons/ions/charged particles that are free to move

39
Q

Explain why graphite conducts electricity

A

Graphite has delocalised electrons between the layers that can move through the structure and carry charge

40
Q

Explain why graphite can act as a lubricant

A

Weak forces between layers which are free to slide over each other

41
Q

What is graphene?

A

One layer of graphite

42
Q

What is a fullerene?

A

Substance made of carbon atoms arranged in a cage

43
Q

What type of substance are methane and water?

A

Simple molecular (or simple molecules)

44
Q

What is a molecule?

A

A group of atoms chemically bonded together

45
Q

Describe the structure of simple covalent molecules

A

Strong covalent bonds between atoms, weak forces holding the molecules together

46
Q

What are intermolecular forces?

A

Weak forces between molecules which hold them together

47
Q

Explain why methane has a low melting point

A

It is a simple molecular substance with weak forces between the molecules (which are easy to break)

48
Q

Describe the main features of metals in terms of their structure

A

Positive metal ions arranged in layers surrounded by delocalised electrons

49
Q

Explain why metals can conduct electricity

A

Delocalised electrons are free to carry charge

50
Q

What is crude oil?

A

A mixture of hydrocarbons

51
Q

What is crude oil formed from?

A

The remains of ancient biomass (mostly plankton)
that was buried in mud

52
Q

What is a hydrocarbon?

A

A compound made of atoms of carbon and hydrogen only

53
Q

What is a general formula?

A

A mathematical formula which allows you to work out the chemical formula of a substance

54
Q

What is an alkane?

A

A hydrocarbon with only single bonds

55
Q

What is meant by the term saturated?

A

A compound that contains single bonds only

56
Q

Name the first four alkanes

A

Methane, ethane, propane, butane

57
Q

What is the general formula for alkanes?

A

CnH2n+2

58
Q

How does boiling point change with the length of an alkane?

A

The longer the alkane, the higher its boiling point

59
Q

How does viscosity change with the length of an alkane?

A

The longer the alkane, the more viscous (the thicker) it is

60
Q

How does flammability change with the length of an alkane?

A

The longer the alkane, the less flammable it is

61
Q

What is fractional distillation?

A

A process used to separate mixtures of substances with different boiling points

62
Q

State the meaning of the term fraction

A

A group of hydrocarbons with similar boiling points

63
Q

What are the steps involved in fractional distillation?

A

1) Crude oil is heated and vaporised, different molecules rise up the fractionating column and cool down.

2) There is a temperature gradient in the column so the column is hotter at the bottom and colder at the top.

3) The different fractions condense at different points on the column due to their different boiling points.

4) Long chain hydrocarbons condense at the bottom and shorter chain hydrocarbons condense further up.

64
Q

Why is fractional distillation important?

A

Because the different fractions have different Uses

65
Q

What is a fuel?

A

A substance which when reacted with oxygen releases energy

66
Q

Name five fuels we obtain from crude oil

A

Petrol, diesel, kerosene, heavy fuel oil and liquefied petroleum gases

67
Q

What is combustion?

A

The reaction of a fuel with oxygen

68
Q

What are the products of complete
combustion?

A

Carbon dioxide and water

69
Q

When does incomplete combustion occur

A

When there is not enough oxygen present

70
Q

What is cracking?

A

The process of breaking down a long hydrocarbon into smaller hydrocarbons

71
Q

What are the products of cracking?

A

Short alkanes and alkenes

72
Q

Why is cracking important?

A

Because smaller hydrocarbons are more in demand

73
Q

What are the two types of cracking?

A

Catalytic and thermal cracking

74
Q

What catalyst is used in catalytic
cracking?

A

Zeolite

75
Q

What is the pressure for catalytic
cracking?

A

Moderate pressure

76
Q

What are the conditions for thermal cracking?

A

High temperature and high pressure

77
Q

What bonds are broken in cracking?

A

C-C bonds

78
Q

What is the major product formed
through thermal cracking?

A

Alkenes

79
Q

What are the major products formed through catalytic cracking?

A

Aromatic hydrocarbons and motor fuels

80
Q

How do you test for an alkene?

A

React it with bromine water

81
Q

What is the colour change when an alkene reacts with bromine water?

A

Turns from orange to colourless

82
Q

What type of polymerization do alkenes undergo?

A

Addition polymerisation

83
Q

Why is it beneficial for some polymers to be biodegradable?

A

To prevent the build up of waste in landfills

84
Q

Explain how oxides of nitrogen are formed in car engines

A

Nitrogen from the air reacts with oxygen at high temperatures

85
Q

State why it is desirable to decrease emissions of oxides of nitrogen from vehicles

A

To reduce the formation of acid rain and to decrease respiratory problems

86
Q

Explain why sulfur compounds should be removed from fractions before they are used for central heating fuel

A

On combustion, sulfur compounds produce SO2 which causes acid rain