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Chemistry PPE revision Flashcards

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1
Q

what is an atom?

A

smallest part of an element that can exist

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2
Q

What is the radius of an atom?

A

1x10 to the power of -10 m

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3
Q

What is the radius of the nucleus of an atom?

A

1x10 to the power of -14 m

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4
Q

What is an element?

A

Substances made up of only one type of atom

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5
Q

what is a compound?

A

.A substance containing two or more different elements, chemically combined

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6
Q

What is the only way compounds can be separated into elements?

A

By chemical reactions

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7
Q

What is a chemical reaction?

A

Always involves the formation of one or more new substances and often involve an energy change

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8
Q

What is the charge of a proton and where are they found?

A

Positively charged and found in the nucleus

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9
Q

What is the charge of a neutron and where are they found?

A

No charge (neutral) and found in the nucleus

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10
Q

What is the charge of an electron and where are they found?

A

Negatively charged and found in shells around the nucleus

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11
Q

What is the relative charge and relative mass of a proton?

A

Relative charge: +1
Relative mass: 1

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12
Q

What is the relative charge and relative mass of a neutron?

A

Relative charge: 0
Relative mass: 1

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13
Q

What is the relative charge and relative mass of an electron?

A

Relative charge: -1
Relative mass: 1/2000 (very small)

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14
Q

Where is almost all of the mass of an atom found?

A

In the nucleus

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15
Q

What is an isotope?

A

Atoms of the same element that have the same number of protons but a different number of neutrons

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16
Q

What is an ion?

A

A charged particle that forms when an atom or molecule gains or loses electrons

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17
Q

Where are electrons found?

A

In shells (sometimes referred to as energy levels)

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18
Q

How many electrons can fit in the first shell of an electron?

A

Up to 2

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19
Q

How many electrons can fit in the second shell of an electron?

A

Up to 8

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20
Q

How many electrons can fit in the third shell of an electron?

A

Up to 8

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21
Q

What is the mass number?

A

The number of protons + neutrons

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22
Q

What is the atomic number?

A

The number of protons

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23
Q

Why do atoms have no overall charge?

A

There is the same number of positive protons and negative electrons that cancel each other out

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24
Q

What must negatively charged ions have?

A

One more electron than proton

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25
Q

What is relative atomic mass?

A

The average mass of all the atoms of an element

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26
Q

What is the equation to calculate relative atomic mass?

A

Relative atomic mass = (mass of isotope 1 x percent abundance of isotope 1) + (mass number of isotope 2 x percent abundance of isotope 2) / 100

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27
Q

What is a mixture?

A

A mixture consists of two or more elements or compounds not chemically combined

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28
Q

What are the different ways mixtures can be separated?

A

.filtration
.crystallisation
.simple distillation
.fractional distillation
.chromatography

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29
Q

What is filtration used for?

A

To separate mixtures of insoluble solids (eg sand) and liquids (eg water)

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30
Q

what happens during filtration?

A

.pour a mixture of insoluble solid and liquid through some filter paper
.the insoluble solid will then stay in the filter paper because its particles are to large to pass through
.and the liquid passes through the filter paper and will gather in the flask

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31
Q

When is simple distillation used?

A

To separate a solvent from a solution when we want to keep the liquid

Eg. producing water from salt solution

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32
Q

What happens during simple distillation?

A

.the solution is heated using a Bunsen burner
.the liquid part evaporates and becomes a vapour, rising up
.the vapour passes through the condenser where it is cooled
.when the vapour is cools it will condense back down to a liquid
.this then separates the liquid from the dissolved solid

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33
Q

When is fractional distillation used?

A

To separate two or more liquids with different boiling points

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34
Q

What happens during fractional distillation?

A

.The mixture is heated to the temperature of the liquid with the lowest boiling point
.the liquid with the lowest boiling point will evaporate first
.it will pass up through the fractionating column and through condenser where it cool and condenses
.when all of this substance has evaporated and condensed we have the two liquids

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35
Q

When is crystallised used?

A

to separate a dissolved solid from a solution

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36
Q

What happens during crystallisation?

A

.gently heat the mixture in a evaporating basin
.some of the solvent (eg water) will evaporate making the solution more concentrated
.remove from heat when crystals begin to form
.leave to cool and filter to remove excess liquid
.leave the crystal to dry

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37
Q

When is chromatography used?

A

To separate mixtures of coloured compounds

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38
Q

What happens during chromatography?

A

.A spot of the mixture is placed on a pencil line near the bottom of a piece of chromatography paper
.paper is placed vertically upright in a solvent (eg water)
.the solvent is soaked up by the paper, carrying the different components with it
.different components move at different rates. This separates them
.if we had a mixture, we would see the spot move up the chromatography paper, and separate and give us two different spots or more

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39
Q

Why is pencil used in chromatography?

A

It is insoluble in water so it doesn’t move

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40
Q

What was Daltons model of the atom like?

A

.an atom is a solid sphere that cannot be created, destroyed or divided into smaller parts
.different types of spheres make up different elements
.the sphere does not contain protons, neutrons or electrons

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41
Q

Who made the plum pudding model?

A

J.J Thomson

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42
Q

Who made the plum pudding model?

A

J.J Thomson

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43
Q

What did J.J Thomson discover about the atom?

A

.The atom is not a solid sphere
.A cloud of positive charge with negative electrons embedded within it

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44
Q

Who made the nuclear model?

A

Rutherford

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45
Q

What is rutherfords alpha scattering experiment?

A

.He fired alpha particles at a thin sheet of gold foil
.If the plum pudding model was true, the alpha particles would bounce back
.however, most passed straight through
.some were deflected and very few bounced straight back

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46
Q

What were the results of the alpha scattering experiment?

A

.The mass of an atom is concentrated in a central nucleus
.the nucleus had to be positively charged to repel the positive alpha particles
.most of the atom was empty space as most passed straight through

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47
Q

Who made the electron shell model?

A

Bohr

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48
Q

Who made the electron shell model?

A

Bohr

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49
Q

What did Bohr discover about atoms?

A

.electrons orbit the nucleus at specific distances in shells/energy levels

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50
Q

Who discovered the neutron?

A

James Chadwick carried out experiments that provided evidence to show the existence of neutrons in the nucleus

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51
Q

Why is it called the periodic table?

A

Similar properties occur at regular intervals

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52
Q

What are the columns called on the periodic table?

A

Groups

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53
Q

What are the rows called on the periodic table?

A

Periods

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54
Q

What are groups within the periodic table?

A

Elements with similar properties are arranged in columns known as as groups

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55
Q

What do elements in the same group have?

A

The same number of electrons in their outer shell

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56
Q

What does the group number tell us about an element?

A

How many electrons are in the outer shell of

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57
Q

What do elements in the same period have?

A

The same number of electron shells

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58
Q

How did scientists arrange elements before the discovery of protons, neutrons and electrons? And what was the fault of this?

A

.In order of atomic weight

.some elements were placed into incorrect groups as their chemical properties were ignored

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59
Q

Why did Mendeleev leave gaps in his periodic table?

A

To leave room for undiscovered elements

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60
Q

What are elements that react to form positive ions?

A

Metals

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61
Q

What are elements that react to form negative ions?

A

Non-metals

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62
Q

Where are metals found on the periodic table?

A

To the left hand side of the periodic table

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63
Q

Where are non metals found on the periodic table?

A

To the right hand side of the periodic table

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64
Q

What are the properties of group 0 elements?

A

.full outer shell of electrons
.unreactive
.do not form molecules. They exist as Ne, He, etc

65
Q

Why are group 0 elements unreactive?

A

Because they have a full outer shell of electrons

66
Q

How does the boiling point of the group 0 elements change down the group?

A

The boiling point increases

67
Q

What are the properties of group 1 elements?

A

.1 electron in their outer shell
.react with oxygen, chlorine and water

68
Q

What are the properties of group 1 elements?

A

.1 electron in their outer shell
.react with oxygen, chlorine and water

69
Q

How does the reactivity of the group 1 elements change down the group? And why does this happen?

A

.Reactivity increases

.the atoms increase in size
.there are more shells, so the outer shell is further away from the nucleus
.the electrostatic attraction between the nucleus and the electron is weaker
.so it is easier to lose the one outer electron

70
Q

What is the equation for reactions with water in group 1?

A

Metal + water -> metal hydroxide + hydrogen

71
Q

why do group 1 elements get given the name “alkali metals”?

A

When they react with water, they form an alkali

72
Q

What is given off during reactions with water?

A

Heat

73
Q

What is observed when alkali metals react with water?

A

.fizzing due to the formation of hydrogen gas
.the solid metal disappears because the metal gets used up

74
Q

What is the equation for reactions with oxygen in group 1?

A

Metal + oxygen -> metal oxide

75
Q

What is the equation for reactions with chlorine in group 1?

A

Metal + chlorine -> metal chloride

76
Q

What are the properties of group 7 elements?

A

.have 7 electrons in their outer shell
.they are non metals
.consists of pairs of atoms

77
Q

How does the reactivity of group 7 elements change down the group?

A

Reactivity decreases

78
Q

Why does the reactivity of the group 7 elements decrease down the group?

A

.the atoms increase in size
.more shells so the outer shell is further away from the nucleus
.the electrostatic attraction between the nucleus and the outer shell is weaker
.its harder to gain an electron to fill the outer shell

79
Q

Why does the melting and boiling point of the group 7 elements increase down the group?

A

.the molecules increase ib size
.the intermolecular forces become stronger
.more energy required to overcome the forces of attraction

80
Q

What is the state of fluorine, chlorine, bromine and iodine at room temperature?

A

Fluorine- Gas
Chlorine- Gas
Bromine- Liquid
Iodine- Solid

81
Q

How does the relative molecular mass change down group 7 elements?

A

Increases down the group

82
Q

What is the appearance of group 7 elements at room temperature?

A

Fluorine- yellow
Chlorine- yellow-green
Bromine-red-brown
Iodine- grey

83
Q

What is the colour in solution of group 7 elements?

A

Chlorine- pale green
Bromine- orange
Iodine- dark brown

84
Q

What happens with group 7 reactions with metals?

A

They react with metals to produce salts

85
Q

What happens with group 7 reactions with non metals?

A

When they react with hydrogen they form hydrogen halides

86
Q

What is a displacement reaction?

A

When more reactive elements can take the place of less reactive elements in a compound

87
Q

What happens when we react potassium chloride with bromine or iodine?

A

No reaction

88
Q

What happens when we react potassium bromide with chlorine or iodine?

A

Chlorine- displaces bromine ions, orange colour observed

Iodine- no reaction

89
Q

What happens when we react potassium iodide with chlorine and bromine?

A

Chlorine- chlorine displaces iodide ions, brown colour observed

Bromine- bromine displaces iodide ions, brown colour observed

90
Q

what is melting?

A

going form a solid to a liquid

91
Q

What is boiling?

A

going from a liquid to a gas

92
Q

what is condensing?

A

Going from a gas to a liquid

93
Q

What is freezing?

A

Going from a liquid to a solid

94
Q

What is ionic bonding? And what does it occur between?

A

.the strong electrostatic attraction between oppositely charged ions

.metals and non metals

95
Q

What happens during ionic bonding?

A

When a metal reacts with a non metal atom electrons from the outer shell of the metal atom are transferred. Metal atoms lose electrons and become positively charged ions, also known as cations

Non metals gain electrons and become negatively charged ions, also known as anions

after reacting both the metal and non metal ions have a full outer shell

96
Q

What is an ionic compound?

A

.a giant lattice structure of ions held together by strong electrostatic forces of attraction between oppositely charged ions

97
Q

What is an empirical formula?

A

The simplest whole number ratio of atoms or ions in a structure

98
Q

What are advantages and disadvantages of a dot and cross diagram for ionic compounds?

A

Advantages:
Shows the transfer of electrons
Disadvantages:
.Doesn’t show hot the ions are arranged in 3D space
.doesn’t show relative sizes of the ions

99
Q

What are advantages and disadvantages of the 3D ball and stick diagram for ionic compounds?

A

Advantages:
.shows the arrangement of ions in 3D space
Disadvantages:
.uses sticks for bonds which is misleading because the forces of attraction between ions act in all directions
.shows lots of free space between ions which isn’t actually there

100
Q

What are advantages and disadvantages of a 2D diagram for ionic compounds?

A

Advantages:
.shows the arrangement of ions in one layer
Disadvantages:
.doesnt show the different layers of ions
.doesnt show the 3D arrangement in space

101
Q

What are advantages and disadvantages of a 3D diagram for ionic compounds?

A

Advantages:
.shows the 3D arrangement in space
Disadvantages:
.not to scale
.gives no information about the forces of attraction between ions

102
Q

What are the properties of ionic compounds

A

.high melting points
.high boiling points
.conducts electricity when melted or dissolved in water
.do not conduct electricity when in the solid state

103
Q

Why do ionic compounds have high melting or boiling points?

A

.strong electrostatic attractions between oppositely charged ions
.large amounts of energy needed to overcome the forces of attraction

104
Q

why do ionic compounds conduct electricity when melted or dissolved in water?

A

The ions are free to move and the charge can flow freely

105
Q

What is a covalent bond?

A

A bond formed when electrons are shared between non metal atoms

106
Q

What are substances with giant covalent structures?

A

Solids with very high melting points

107
Q

What are examples of giant covalent structures?

A

.diamond- one of the hardest substances
.graphite- conducts electricity
.silicon dioxide- naturally found in sand- high melting and boiling point

108
Q

Why do giant covalent structures have high melting points?

A

Because the many strong covalent bonds between atoms must be broken, this requires a lot of energy

109
Q

Why do most giant covalent structures not conduct electricity?

A

Because they have no delocalised electrons or ions, they are free to move to carry charge.

110
Q

What happens when boiling or melting substances made up of small molecules?

A

The weak intermolecular forces between molecules are overcome and this doesn’t require a lot of energy

111
Q

What do bigger molecules have?

A

Stronger intermolecular forces, so they have higher melting and boiling points

112
Q

Why do small molecules not conduct electricity?

A

They have no charge

113
Q

What are polymers?

A

Very large molecules made up of many repeating units joined by covalent bonds

114
Q

What are polymer chains held together by?

A

Intermolecular forces

115
Q

Why are intermolecular forces between polymers really strong? And what does this mean?

A

.Because the polymer is such a long molecule

.this means polymers have higher melting points compared to smaller molecules and are solid at room temperature

116
Q

What are polymers used for?

A

To make plastic

117
Q

What are some advantages and disadvantages of using a dot and cross diagram for covalent compounds?

A

Advantages:
.show the transfer of electrons
.shows which atom the bonding electrons come from
Disadvantages:
.doesn’t show how the atoms are arranged in 3D space
.doesn’t show relative sizes of the atoms

118
Q

What are some advantages and disadvantages of using a 3D ball and stick diagram for covalent compounds?

A

Advantages:
.shows the arrangement of atoms in 3D space
.shows shape of the molecule
Disadvantages:
.used sticks for bonds and doesn’t show that the bonds are forces
.atoms placed far apart from each other but in reality gaps are much smaller

119
Q

What are some advantages and disadvantages of using a 2D diagram for covalent compounds?

A

Advantages:
.shows what atoms are in a molecule and how they are connected
Disadvantages:
.doesn’t show the relative size of the atoms and bonds
.doesnt show the 3D arrangement in space

120
Q

What are some advantages and disadvantages of using a 3D diagram for covalent compounds?

A

Advantages:
.shows the 3D arrangement in space
Disadvantages:
.not scale
.gives no information about the forces of attraction between atoms

121
Q

Describe the structure and bonding in diamond?

A

.giant covalent structure
.every carbon atom forms 4 strong covalent bonds with other carbon atoms

122
Q

Why is diamond so hard?

A

.giant covalent structure
.every carbon atom forms 4 string covalent bonds with other carbon atoms so it requires a lot of energy to break

123
Q

Why does diamond not conduct electricity?

A

.Every carbon atom forms 4 strong covalent bonds with other carbon atoms
.so there are no delocalised electrons or ions free to move

124
Q

Describe the bonding and structure in graphite

A

.made of only carbon atoms
.forms hexagonal rings arranged in layers
.each carbon atom forms strong covalent bonds with 3 other atoms , this leaves carbon with one spare electron, this is delocalised and free to move through the layers

125
Q

What are group 1 elements know as?

A

Alkali metals

126
Q

What are group 2 elements known as?

A

Alkali Earth metals

127
Q

What are group 7 elements know as?

A

The halogens

128
Q

What are group 0 elements know as?

A

Noble gasses

129
Q

What does graphite conduct electricity?

A

Each carbon carbon atom has one spare electron which is delocalised and free to move around and carry electrical charge through the layers

130
Q

Why is graphite slippery?

A

The layers have weak intermolecular forces between them so it doesn’t require much energy to overcome

131
Q

What is graphene?

A

A single layer of graphite

132
Q

Graphene has strong covalent bonds between carbon atoms, what does this mean?

A

.it is very strong
.has high melting and boiling points
This is because it will take a lot of energy to break the strong covalent bonds

133
Q

How many carbon atoms is graphene bonded to?

A

3

134
Q

Is graphene a conductor of electricity?

A

Yes

135
Q

What are fullerenes?

A

Molecules of carbon atoms with hollow shapes

136
Q

How can fullerenes be arranged?

A

As a tube or as a ball

137
Q

What is a property of a nano tube?

A

A high tensile strength so are difficult to break

138
Q

What is a property of a nano tube?

A

A high tensile strength so are difficult to break

139
Q

What are nanotubes useful for?

A

Nanotechnology, electronics and materials

140
Q

What is a nanotube?

A

Cylindrical fullerenes with very high length to diameter ratios

141
Q

What is a buckmister fullerene?

A

A molecule made up of 60 carbon atoms covalently bonded into a spherical shape

142
Q

What are properties of buckmister fullerenes?

A

There are weak intermolecular forces between the molecules- this means buckmister fullerene has a low melting point and is slippery

143
Q

What are buckmister fullerenes used for?

A

As a lubricant and for drug delivery

144
Q

Why do metals have high melting and boiling points?

A

Because metals have giant structures of atoms with strong metallic bonding which means it requires a lot of energy to overcome to strong bonds

145
Q

What are some properties, advantages and disadvantages of pure metals

A

.atoms are arranged in layers
.these layers can slide over each other which means that they can be bent and shaped
.pure metals can be to soft

146
Q

How are alloys made and why are they better than pure metals

A

.If we mix pure metals with other elements we can make an alloy
.atoms of different elements are different sizes.The distorts the layers
.the layers can’t slide over each other as easily- more force is required
.this makes alloys harder and stronger than pure metals

147
Q

What are properties of metals?

A

.made up of giant structures of atoms arranged in a regular pattern
.the electrons in the outer shell of the metal atoms are delocalised, forming metal ions
.these delocalised electrons are free to move through the layers of metal ions

148
Q

Why can metals conduct electricity?

A

The delocalised electrons are free to move between the layers

149
Q

Why are metals good conductors of thermal energy?

A

The delocalised electrons transfer energy

150
Q

What causes metallic bonding?

A

The sharing of delocalised electrons

151
Q

What is the law of conservation of mass?

A

No atoms are lost or made during a chemical reaction. The mass of the products equals the mass of the reactants

152
Q

What happens to mass in an in closed system?

A

Mass will be observed to be conserved

153
Q

What happens to mass in a non-enclosed system?

A

Gasses can enter and leave the system, this will make it look like the mass has changed when it hasn’t

154
Q

What is relative formula mass?

A

The sum of the relative atomic masses of the atoms in the numbers shown in its formula

155
Q

What is the equation to calculate percentage by mass?

A

Total relative atomic mass of atoms of the element/relative formula mass of compound x100

156
Q

How can we calculate uncertainty?

A

.using the range of a set of repeated experiments
.looking at the resolution of the measuring instrument

157
Q

How do we calculate uncertainty?

A

.work out the range of the results
.the uncertainty is half of the range

158
Q

What is resolution?

A

The smallest division in apparatus

Science (9 decks)

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