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Science A (Core): Chemistry (I) > Science A (Core): Chemistry > Flashcards

Science A (Core): Chemistry Flashcards

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1
Q

Draw and label an atom

A
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2
Q

What does the periodic table contain?

A

Elements

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3
Q

What do these terms means:-

Atom

Molecule

Element

Compound

Mixture

A

Atom – single particle which are the building blocks of all materials

Molecule – group of atoms bound together representing the smallest unit of a chemical compound

Element – pure substance with only 1 type of atom (e.g. gold)

Compound – 2 or more elements chemically bound (e.g. carbon dioxide)

Mixture – more than 1 element or compound not chemically bound (e.g. air)

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4
Q

What are the symbols for the following atoms: -

Oxygen

Nitrogen

Chlorine

Hydrogen

Sodium

Copper

Potassium

Helium

Calcium

Zinc

Iron

Carbon

A

Oxygen (O)

Nitrogen (N)

Chlorine (Cl)

Hydrogen (H)

Sodium (Na)

Copper (Cu)

Potassium (K)

Helium (He)

Calcium (Ca)

Zinc (Zn)

Iron (Fe)

Carbon (C)

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5
Q

What happens to atoms when they chemically react to form a compound?

A

They share, give away, or take electrons

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6
Q

What are the names of these compounds, and which atoms are found in them?

H2O

CaCO3

H2SO4

HCl

CO2

A

Water (H2O)

Calcium carbonate (CaCO3)

Sulfuric acid (H2SO4)

Hydrochloric acid (HCl)

Carbon dioxide (CO2)

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7
Q

What is limestone used to produce?

A

Cement, concrete, glass and building materials

Heated with clay = cement

Cement + sand = mortar

Sand + gravel = concrete

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8
Q

What is a quarry, and what are the pros and cons of quarrying for materials?

A

A quarry is a place where large amounts of raw materials such as ores and limestone are removed from the ground

Pros – employment / economic benefits

Cons – noisy / ugly / habitat destruction

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9
Q

What is the equation for when a metal reacts with water?

A

Metal + Water → Metal Hydroxide + Hydrogen

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10
Q

What is the equation for when a metal reacts with air?

A

Metal + Oxygen → Metal Oxide

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11
Q

What are cations?

A

Cations are atoms which lose electrons (having less electrons than protons) which have a positive charge

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12
Q

What are anions?

A

Anions are atoms which gain electrons (having more electrons than protons) which have a negative charge

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13
Q

Do metal atoms lose or gain electrons?

A

Metal atoms lose electrons becoming positive in charge (cations)

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14
Q

Do non-metal atoms lose or gain electrons?

A

Non-metal atoms gain electrons becoming negative in charge (anions)

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15
Q

How does an electrostatic precipitator work?

A
  1. Smoke particles pick up a negative charge
  2. Smoke particles are attracted to the collecting plates
  3. Collecting plates are knocked to remove the smoke particles
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16
Q

What happens in the reaction between sodium and chlorine?

A

sodium + chlorine → sodium chloride

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17
Q

What happens in the reaction between magnesium and oxygen?

A

magnesium + oxygen → magnesium oxide

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18
Q

What happens in the reaction between calcium and chlorine?

A

calcium + chlorine → calcium chloride

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19
Q

How is pure iron made into steel?

How does the change in structure affect its properties?

A

Add carbon – this means the atoms cannot slide past one another as easily, making it stronger (steel)

High carbon steel = hard

Low carbon steel = easily shaped

Stainless steel = resistant to corrosion

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20
Q

Why is the extraction of aluminium and titanium so expensive?

A

There are many stages and lots of energy is needed

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21
Q

What is an alloy and why are they used?

Give some examples

A

Alloys are mixtures of metals with other elements, e.g. iron + carbon → steel

They have a combination of properties, e.g. bronze, brass, steel etc…

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22
Q

What is a smart alloy and why are they used?

Give some examples

A

Smart alloys can return to their original shape after being deformed – e.g. glasses and braces

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23
Q

Where are the transition metals found on the periodic table?

What are the general properties of the transition metals, and what are they used for?

A

Transition metals are found in the middle of the periodic table and used for building materials

Easily shaped

Hard (strong)

Good conductors (heat + electricity)

Less reactive

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24
Q

How is copper usually extracted?

What is it used for?

A

Electrolysis extracts copper

Copper is used for electrical cables

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25
Q

What is an ore?

A

A rock with enough metal to make it worthwhile extracting the metal from

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26
Q

Why is it important to recycle?

A

Because we only have a limited supply of resources, e.g. oil (recycle plastic) and aluminium (recycle ores) and it is better for the environment

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27
Q

Some metals can be extracted from ores using carbon – how does this work?

A

If carbon is more reactive that the metal, it reacts with the oxygen to purify it

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28
Q

Give 2 metals that carbon can be used to extract

Give 2 metals that carbon cannot be used to extract

A

Carbon can extract anything less reactive than itself (e.g. iron and lead)

Carbon cannot extract anything more reactive than itself (e.g. magnesium and aluminium)

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29
Q

Why are aluminium and titanium such useful metals?

Why can they not be extracted with carbon?

A

They have low density and are resistant to corrosion

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30
Q

What are the properties of pure iron?

Explain why this is

A

Easily shaped and too soft for most jobs because of the regular arrangement of the atoms (they can slide past one another)

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31
Q

What is a covalent bond?

A

A bond formed between two non-metal atoms, sharing electrons

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32
Q

Draw an electron diagram showing how hydrogen bonds

A

Hydrogen atoms can each form one covalent bond

One pair of electrons is shared in a hydrogen molecule (H2)

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33
Q

Draw an electron diagram showing how oxygen bonds

A

Oxygen atoms can each form two covalent bonds

Two pairs of electrons are shared in an oxygen molecule (O2) – a double bond

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34
Q

Draw an electron diagram showing how water bonds

A

Hydrogen atoms can each form one covalent bond, while oxygen atoms can each form two covalent bonds

Two pairs of electrons are shared in a water molecule (H2O)

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35
Q

What are they signs of a chemical reaction

A

Signs of a chemical reaction include: -

A change in colour

A gas coming off (you may see fizzing or bubbling)

A change in temperature (the reaction mixture may get hotter)

A solid may be formed when two solutions are mixed together

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36
Q

What are the properties of the transition metals?

A

They are metals
They form coloured compounds

They are good conductors of heat and electricity

They can be hammered or bent into shape easily

They are less reactive than alkali metals

They have high melting points (but mercury is a liquid at room temperature)

They are hard and tough

They have high densities

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37
Q

Where are the transition metals found on the periodic table?

A

The transition metals are found in the large block between groups II and groups III in the periodic table

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38
Q

What is electrolysis?

A

Electrolysis is a way to extract reactive metals from their ores, however it is very expensive as a large amount of electricity is required

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39
Q

What are the steps involved in electrolysis?

A

Make the metal ore molten to release the metal ions so they can move

Electrodes cause the metal ions (+ve) to flow to the –ve electrode

At the cathode the ions pick up spare electrons turning from ions into atoms where they sink and can be collected

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40
Q

Where do the ions go during electrolysis?

A

Positively charged ions move to the –ve electrode whilst negatively charged ions move to the +ve electrode

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41
Q

What is phytomining?

A

Phytomining uses plants to absorb naturally occurring metal compounds (including copper) when they grow

Once a significant amount of metal compound has been absorbed the plants are burned, producing ash which contains the metal compounds

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42
Q

What is bioleaching?

A

Bioleaching uses bacteria to produce leachate solutions that contain metal compounds…

Some bacteria can live by using the energy of the bonds between sulfur and copper – in doing so this separates the metal from the ore

The process is efficient, but very slow!

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43
Q

What is the overall charge of an atom and what are the charges of the sub-atomic particles?

A

Atoms have a neutral charge (they have the same number of protons as electrons)

Protons are positive

Electrons are negative

Neutrons are neutral

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44
Q

How can we work out the proton, electron and neutron numbers of an atom, e.g. potassium: -

A

The periodic table shows us the atomic number (bottom number = protons (and therefore electrons) as well as the atomic mass (top number = protons + neutrons)

Proton number = atomic number

Electron number = atomic number

Neutron number = atomic mass – atomic number

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45
Q

How do electrons fill up in their shells?

How many electrons would you find in the outer shell of a group 1, group 2, group 7 and group 8 element?

A

Electrons occupy the lowest energy shell before filling the next, with a maximum of 2 e- in shell 1; 8 e- in shell 2; 8 e- in shell 3

Group 1 elements = 1 e- in outer shell

Group 2 elements = 2 e- in outer shell

Group 7 elements = 7 e- in outer shell

Group 8 elements = 8 e- in outer shell

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46
Q

Where are the metals and non-metals found on the periodic table?

A

Metals are found on the left hand side, non-metals on the right

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47
Q

What happens to the mass of materials during a chemical reaction?

A

Mass stays the same – it does not change in a chemical reaction

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48
Q

Why are the noble gases in group 8 unreactive?

*(Group 8 also known as group 0)

A

They have a full outer shell so do not need to gain or lose any electrons, so are unreactive

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49
Q

Why are some metals such as gold and silver found as the metal itself within the Earth without the need for extraction?

A

Some metals such as gold and silver are extremely unreactive, and can be found within the Earth as the metal itself without the need for chemical extraction from an ore

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50
Q

How pure is iron from a blast furnace and what is the effect of the impurities?

A

96% pure – the impurities cause brittleness in the iron

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51
Q

What are the properties of copper?

A

Good conductor of heat and electricity, hard but malleable, does not react with water etc…

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52
Q

What is the chemical name and chemical formula for limestone

A

CaCO3

53
Q

What happens during the thermal decomposition of limestone?

What does calcium oxide and water react to form?

A

Calcium Carbonate → Calcium Oxide + Carbon Dioxide

Calcium hydroxide (a base to neutralise acids)

54
Q

What do metal carbonates and acids form?

A

Carbon dioxide, water and salt

55
Q

What is calcium hydroxide?

How is it used and what does it test for?

A

Calcium hydroxide is limewater

It tests for the presence of carbon dioxide (goes cloudy)

56
Q

What does calcium hydroxide + carbon dioxide form?

A

Calcium carbonate

57
Q

How can hydrocarbons be broken down into smaller molecules?

A

Cracking

58
Q

What is an alkane?

Give an example and draw it

A

An alkane is a hydrocarbon, e.g. ethane

59
Q

What kind of reaction happens when large hydrocarbons are broken down?

A

Thermal decomposition

60
Q

What is the general formula for an alkane?

A

CnH2n+2

61
Q

What is the general formula for an alkene?

Give an example and draw it

A

CnH2n – e.g. propene

62
Q

How can you test for an alkene?

A

Bromine water – goes clear

63
Q

What conditions are needed for cracking of large hydrocarbons?

A

Cracking – heat hydrocarbons and vapourise them, then pass these vapours over a catalyst

64
Q

What are the products of cracking useful for?

A

Useful as fuels

65
Q

How can ethanol be made from ethene?

A

Ethene reacted with steam and in the presence of a catalyst = ethanol

66
Q

What is polymerisation?

A

Polymerisation is when small molecules are joined to make longer, more useful molecules (e.g. ethane makes poly(ethane))

67
Q

Give 2 examples of polymers

A

Poly(ethane) and poly(propene)

68
Q

What determines the properties of polymers?

A

What they are made from and the conditions under which they are made

69
Q

Give 6 uses of polymers

A

New packaging, waterproof coatings, dental-polymers, hydrogels, smart materials (shape memory polymers)

70
Q

What are the problems with polymers?

A

Often polymers are not biodegradable causing issues with disposal

71
Q

How can vegetable oil be extracted from fruit and seeds?

A

Crushing, pressing and distilling

72
Q

Why are vegetable oils an important part of our diet?

A

They provide us with nutrient and energy

73
Q

Why are emulsions useful?

A

They are thicker than oil or water and have uses dependent on their special properties – an emulsion is a suspension of fat droplets in water (or some other liquid)

74
Q

What uses do emulsions have?

A

Better texture, coating ability and appearance used in salad dressings and ice cream

75
Q

Vegetable oils that contain double bonds can be detected by what?

A

Reacting with bromine water which changes from orange to colourless

76
Q

How can vegetable oils that are unsaturated be hardened?

A

React them with hydrogen, pass over a nickel catalyst and heat at 60°C

77
Q

What are hydrogenated oils?

A

Hydrogenated oils are vegetable oils that have extra hydrogen in them, making them harder

78
Q

Why are hydrogenated oils useful?

A

They have a higher melting point and so are solid at room temperature, making them useful as spreads (cakes and pastries)

79
Q

What is thermal decomposition?

A

The breaking up of a molecule using heat

80
Q

What is a monomer?

What is a polymer?

A

Monomer – single molecule of a chemical such as ethane

Polymer – more than one monomer joined together such as poly(ethane)

81
Q

What conditions are needed to make ethanol?

Ethanol can also be made by fermenting yeast – what is the equation for this?

A

Steam and a catalyst

Glucose → Carbon dioxide + Ethanol

82
Q

What conditions are needed for hydrogenation?

A

React them with hydrogen, pass over a nickel catalyst and heat at 60°C

83
Q

Give some examples of emulsions

A

Mayonnaise, milk, ice cream, salad dressing etc…

84
Q

What are the benefits, drawbacks and risks of using vegetable oil to make fuel?

A

Advantages: carbon emissions reduced; better for the car; readily available

Disadvantages: specialist equipment needed; unknown risks

85
Q

What are the issues associated with disposing of polymers?

A

Polymers are not biodegradable and so are difficult to dispose of

86
Q

What raw material is used to make plastics?

A

Crude oil

87
Q

What is fractional distillation?

A

A way to separate a mixture into different fractions, based on boiling point

Different hydrocarbons evaporate at different temperatures, after which they are condensed

88
Q

Where is a fractional distillation column the coolest?

A

It is coolest at the top

89
Q

Why is cornstarch used as a replacement for some previous polymers?

A

It is a biodegradable polymer which breaks down more easily

90
Q

Why can combustion be termed as an oxidation reaction?

A

Combustion involves oxygen being added to the fuel (the carbon and hydrogen are oxidised)

91
Q

What causes incomplete combustion

A

A lack of oxygen

92
Q

What potentially dangerous gases are released in the combustion of fossil fuels?

A

Carbon dioxide / monoxide / sulfur dioxides / nitrogen oxides / un-burnt hydrocarbons / particulates

93
Q

Why was Wegener’s continental drift theory not accepted for some time?

A

Continental drift was not accepted for a long time as it was thought the world was shrinking

94
Q

What does the Earth consist of?

A

Crust, mantle, outer core, and inner core

95
Q

How did scientists originally think mountains were formed?

A

Scientists believed that the shrinking of the Earth as it cooled caused the mountains

96
Q

What are tectonic plates?

A

The Earth’s crust and upper part of the mantle is cracked into a number of large pieces, known as tectonic plates

97
Q

What causes the tectonic plates to move?

A

Convection currents cause the movements of the tectonic plates

98
Q

What causes the convection currents?

A

Natural radioactive processes release heat

99
Q

What can happen if the tectonic plates move?

A

Earthquakes and volcanoes

100
Q

How do earthquakes occur?

A

Earthquakes are causes by tectonic plates rubbing against one another

101
Q

How long have the proportions of gases in the atmosphere been as they are?

A

200 million years

102
Q

What gases are in the atmosphere?

A

Nitrogen, oxygen, carbon dioxide, noble gases, and water vapour

103
Q

What are the proportions of the gases in the atmosphere?

A

78% nitrogen

21% oxygen

  1. 04% carbon dioxide
  2. 9% argon

+ small amounts water vapour + noble gases

104
Q

What is distillation?

A

Distillation is when the solution is boiled and the vapour is cooled and collected

105
Q

What chemicals can be used to identify double carbon bonds?

A

Bromine and iodine

106
Q

How do materials biodegrade?

A

If materials biodegrade they are broken down by microorganisms

107
Q

What happened on Earth in the first one billion years?

A

Violent volcanic activity

108
Q

How did the oceans form?

A

The water vapour from the volcanic activity condensed and formed the oceans

109
Q

What was the Earth’s early atmosphere mainly made of?

A

Mainly carbon dioxide with little or no oxygen

110
Q

Which planets are similar to Earth’s early atmosphere?

A

Mars and Venus

111
Q

What was there very little of in the early atmosphere?

A

Oxygen

112
Q

What were there small amounts of in the early atmosphere?

A

Methane and water vapour

113
Q

What produces oxygen?

A

Plants

114
Q

How has the carbon from carbon dioxide been ‘locked up’?

A

Most of the carbon dioxide is locked up in sedimentary rocks as carbonates and fossil fuels

115
Q

How do levels of carbon dioxide rise today?

A

Burning fossil fuels

116
Q

Why is the burning of fossil fuels bad environmentally?

A

Carbon dioxide is thought to be responsible for climate change

Sulfur dioxide and oxides of nitrogen cause acid rain

Solid particles cause global dimming

117
Q

What impact do humans have on the Earth?

A

Humans burn fossil fuels making carbon dioxide

Plastics are difficult to dispose of properly

118
Q

What foods contain hydrogenated oils and why?

A

Margarine – this hardens the vegetable oil, turning it more solid so it can be spread

119
Q

Why are long hydrocarbon chains ‘cracked’?

A

Long hydrocarbon chains are not as useful as short hydrocarbon chains so they are ‘cracked’ into smaller chains

120
Q

What do cars have to reduce carbon monoxide, nitrogen oxides and un-burnt hydrocarbons?

A

Catalytic converters

Carbon Monoxide + Nitrogen Oxide → Nitrogen + Carbon Dioxide

Nitrogen Oxides → Nitrogen + Oxygen

Hydrocarbon + Oxygen → Carbon Dioxide + Water

121
Q

What alternatives are there to fossil fuels?

A

Hydrogen (although requires energy to split in the first place) and bio-fuels (controversy growing plants for fuel when land could be used for food)

122
Q

What is the Miler and Urey experiment of 1952?

A

An experiment to recreate life replicating the early conditions on Earth (ammonia, methane, hydrogen, water and electrical sparks simulating lightning)

Carbon compounds had formed (amino acids) which make proteins suggesting this is how life began (bacteria)

123
Q

Crude oil is a mixture – what is a mixture

A

2 or more elements or compounds which are not chemically joined

124
Q

What is the formula for methane, ethane, propane and butane?

A

Methane – CH4

Ethane – C2H6

Propane – C3H8

Butane – C4H10

125
Q

How do the properties of long and short chain hydrocarbons differ in terms of boiling point, viscosity and flammability?

A

As hydrocarbon length increases the boiling point increases, the hydrocarbon becomes more viscous and less flammable

126
Q

What is the formula for ethene and how would polyethene be represented?

A

Ethene – C2H4

127
Q

What are the advantages and disadvantages of cooking in oil rather than in water?

A

Advantages: vegetable oils have higher boiling points than water so can be used to cook foods at higher temperatures producing quicker cooking

Disadvantages: cooking in oil increases the energy the food releases when eaten

128
Q

How can sulfur dioxide gas released during the burning of fossil fuels be prevented?

A

Sulfur can be removed before burning as well as sulfur dioxide being removed after combustion

Science A (Core): Chemistry (I) (1 decks)

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