⚛ Chemistry Paper 1 Flashcards
1
Q
Chem: what is the equation for atom economy
A
2
Q
Chem: what type of atoms are used in and what happens in covalent bonding
A
2 or more non-metals, sharing electrons
3
Q
Chem: what happens in metallic bonding and in what type of atoms
A
Positive metal ions in a sea of delocalised negative electrons, in metals
4
Q
Chem: what happens in ionic bonding and in what type of atoms
A
Gives/takes electrons, metals and non-metals
5
Q
Chem: what is a activation energy
A
The minimum energy required to start a chemical reaction
6
Q
Chem: what is an energy profile
A
A graph showing energy change during a chemical reaction
7
Q
Chem: what is an exothermic reaction
A
A chemical reaction that releases energy
8
Q
Chem: what is an endothermic chemical reaction
A
A chemical reaction that takes in energy
9
Q
Chem: what happens in a chemical reaction
A
Bonds are broken and formed and atoms are rearranged
10
Q
Chem: how thick is one nm in terms of atoms
A
10 atoms thick
11
Q
Chem: order in terms of size, from smallest to largest, coarse particles, nano particles and fine particles
A
Smallest - largest: nanoparticles, fine particles, coarse particles
12
Q
Chem: what is the size of coarse particles
A
2500 to 10000 nm
13
Q
Chem: what is the size of fine particles
A
100 to 2500 nm
14
Q
Chem: what is the size of nano particles
A
1 to 100 nm thick
15
Q
Chem: is the anode the positive or negative electrode in electrolysis
A
Positive
16
Q
Chem: is the cathode positive or negative in electrolysis
A
Negative
17
Q
Chem: is an anion positive or negative
A
Negative
18
Q
Chem: is a cation positive or negative
A
Positive
19
Q
Chem: what happenes at the negative electrode in electrolysis of aqueous solutions
A
Hydrogen atom forms , only if the metal is more reactive than it
Also electrons transferred to ion to make it an atom
20
Q
Chem: is electrolysis of aqueous solutions what happens at the positive electrode
A
Oxygen produced, unless a halogen present then the halogen is produced
Electron transferred from ion to positive electrode
21
Q
Chem: what is an aqueous solution
A
Something dissolved in water
22
Q
Chem: what is the definition of electrolysis
A
Electrolysis is the process of splitting ionic compounds using electric current
23
Q
Chem: how do you work out moles of an atom
A
Moles= mass / formula mass
24
Q
Chem: how do you work out the formula mass (Mr) of a molecule
A
It is the sum of the elements in the molecule
25
Chem: work out the Mr of K ₂O if the formula mass of of K is 39 and O is 16
39+39+16=94
26
Chem: How do you write ionic equations
Split the equation so
- NaOH ( aq ) + HNO 3 ( aq ) → NaNO 3 ( aq ) + H 2 O ( l ) would become
- Na + OH ( aq ) + H + NO 3 ( aq ) → Na + NO 3 ( aq ) + H 2 + O ( l )
- Then cross out the portions that do not change their charge, this becomes
- OH ( aq ) + H → H 2 O ( l )
27
Chem: what is an ionic equation
It is a chemical equation with all of the things that do not change charge removed
28
Chem: what is oxidation
Oxidation is the loss of electrons and the gain of oxygen
29
Chem: what is reduction
It is the gain of electrons and possibly gain of hydrogen and the loss of oxygen
30
Chem: in electrolysis does reduction or oxidation occur at the positive electrode
Oxidation
31
Chem: in electrolysis does oxidation or reduction occur at the negative electrode
Reduction
32
Chem: what is a half equation
Electrons are represented, they are 2 equations that show how electrons are transferred at each electrode in electrolysis
33
Chem: what is the equation for complete combustion
Hydrocarbon + oxygen -> carbon doxide + water
34
Chem: what is the equation for incomplete combustion
Hydrocarbon + oxygen -> carbon doxide + water + carbon monoxide
35
Chem: what is the definition of carbon footprint
this is the total amount of carbon dioxide and other greenhouse gases that are emitted over the full lifecycle of a product, service or event
36
Chem: what is carbon footprint offsetting
Say you buy a plane ticket, planting trees to offset the greenhouse gasses released by the journey
37
Chem: what is the order of events for the formation of life
Volcanoes, oceans, algiae, plants, animals
38
Chem: what are the percentages of gasses in the atmosphere
Nitrogen-78, oxygen-21, other gasses-1
39
Chem: what are the 4 alkanes you need to remember
Methane, ethane, propane, butane
40
Chem: what is crude oil made of
Fossilised plankton that was buried in mud
41
Chem: what is the definition of a mixture
A substance composed of 2 or more differeent compounds or elements not chemically bonded
42
Chem: what is ionic bonding and in what types of elements does it occur
Giving/taking electrons
Between metals and non metals
43
Chem: what is covalent bonding and in what type of elements does it occur
Sharing electrons
2 non metals
44
Chem: what is metallic bonding and in what type of elements does it occur
Sea of delocalised electrons
Metals
45
Chem: what are the properties of covalently bonded substances
- Non-conductive(no charged particles that can carry a charge)
- low melting point
46
Chem: what are the properties of ionically bonded substances
- Conduct when dissolved in water
- hard and brittle
- high melting and boiling points.
47
Chem: what defines potable water
It is safe to drink, it should have low levels of dissolved salts and of microbes.
48
Chem: what are the 2 ways of getting potable water from salt water
Distillation , reverse osmosis
49
Chem: what is reverse osmosis
It is osmosis where the water moves from low to high concentration because of large amounts of pressure
50
Chem: what is distillation
Where a liquid is evaporated and collected from a mixture
51
Chem: what are the 3 ways water is steralized
UV, chlorine, ozone
52
Chem: what is pure water
Water that is not in a mixture
53
Chem: how many cm3 in a dm3
1000
54
Chem: how do catalysts work
They change the reaction pathway
55
Chem: what are the 5 factors that affect rate of reaction
- temp
- concentration
- catalyst
- pressure
- surface area
56
Chem/bio: how do enzymes make things react
They lower the activation energy
57
Chem: what is a the difference between weak and strong acids
Weak acids have low amounts of ionised hydrogen ions, whereas in strong acids there is a large amount of ionised hydrogen ions
58
chem: what is a mole
1 mol is the unit for amount of substance, its the 6.02 x10^23 atoms
59
chem: what is percentage yield
actual yield / theoretical yield x 100
60
chem: what is the equation for relative formula mass
adding up all of the relative atomic masses of the atoms in a formula
61
Chem: what is the difference in amount of hydrogen ions between PH 2 and PH 1
10x, each jump is a gap of 10x as it is a logarithmic scale
62
Chem: what hydrogen ions constitute acids, are they positive or negative
H+ ions
63
Chem: what hydrogen ions constitute alkalise, what charge are they
OH- ions
64
chem: in electrolysis does reduction happen at the cathode or anode
cathode
65
chem: in electrolysis does oxidation happen at the cathode or anode
anode
66
Chem: what is the difference between giant and simple covalent bonding
- **Simple covalent** - fixed number of atoms in the structure
- **giant covalent** - undefined amount of atoms.
67
Chem: why do simple covalent compounds have low melting and boiling points
The have weak intermolecular forces, this means less energy is needed to overcome these forces
68
Chem: what is the difference between atomic and intermolecular forces
Atomic forces are forces within an atom and intermolecular forces are the forces between atoms.
69
Chem: what are the properties of simple covalent compounds
Low melting and boiling point, do not conduct
70
Chem: what are the properties of giant covalent
High melting and boiling point.
71
Chem: what are the properties of ionic compounds
- High melting and boiling points
- when molten or dissolved they conduct
- when solid they have poor conductivity
72
Chem: what are the properties of metallic bonding
- Electrical/Thermal conductivity
- High melting/boiling point
- Malleability
73
Chem: define concentration
Amount of particles in a given volume
74
Chem: to increase the rate of reaction for an Exothermic reaction by changing temp what do you do, cool or heat? Why?
Cool, if there is less energy in the surroundings it is easier for the reaction to give out energy.
75
Chem: what is a solvent
A liquid in which a solid dissolves
76
Chem: what is a solute
Dissolved solid
77
Chem: what is a solution
A liquid which contains a dissolved solid
78
Chem: what are the 5 ways of separating mixtures
- crystallisation
- filtration
- chromatography
- simple distillation
- fractional distilation
79
Chem: explain fractional distillation
A mixture of several substances is separated by distilling the mixture and then evaporating and collecting the individual components using their individual boiling points
80
Chem: define distillation
Purifying a liquid by heating and cooling
81
Chem: explain simple distillation
It separates 2 liquids with different boiling points, the mixture with the lower boiling point is boiled off and collected
82
Chem: explain crystalization
To separate a soluble substance from a solvent, evaporate the solvent to form crystals of the solute
83
Chem: explain filtration
Used to separate an insoluble solid from a liquid, the mixture is put through a filtration device to collect the liquid and the solid/s
84
Chem: explain chromatography
Used to separate mixtures of soluble substances in a solution, paper chromatography this works on the principle that some substances are more soluble
85
Chem: what is the equation of concentration (used in titrations)
Concentration = moles / volume
86
Chem: define decomposition
The process of breaking down
87
Chem: what is thermal decomposition
A compound that breaks down when heated
88
Chem: what are the 2 catalysts used in catalytic converters
Palladium and platinum
89
chem: what are the properties of the transition metals
- they have high melting and boiling points
- higher dencity
- lower reactivity
- greater strength and hardness
- some of them can be used as catalysts
- form coloured compounds
90
chem: what is an acid
it is a substance that forms H+ ions when dissolved in water
91
chem: what is an alkali
it is a substance that forms OH- ions when dissolved in water
92
chem: when reacting with other substances what charged ions do metal atoms form
posotive
93
chem: what is the reactivity of a metal baced on
its ability to form its posotive ion
94
chem: what is an ion
it is an atom or group of them that has any charge
95
chem: what is a spectator ion
it is an ion that, in a reaction does not change its charge
96
chem: what is the difference between an alkali and a base
Alkalis are soluble (soluble metal hydroxides) and bases are insoluble (insoluble metal hydroxides and metal oxides)
97
chem: when lithium reacts with water what happens
fizzes steadily and floats
98
chem: when potassium reacts with water what happens
reacts quickly, hydrogen produced is instantly ignited and the metal ignites too, buring with a lilack flame
99
chem: when sodium reacts with water what happens
fizzes rapidly and melts, moves around on the waters surface
100
chem: **why** and **how** are metals less reactive than carbon extracted from their ore by carbon
the metal is reduced (looses its oxygen). carbon (in the form of coal) is used because it is cheap and abundent
101
chem: when acids react with metals what is formed
hydrogen and a salt
102
chem: what are the 3
types of base that acids can be neutralised with
- metal carbonates
- metal oxides
- metal hydroxides
103
chem: acid + metal oxide ->
salt + water
104
chem: acid + metal hydroxide ->
salt + water
105
chem: acid + metal carbonate ->
salt + water + carbon dioxide
106
chem: what are the 3 ways of detecting the acidity or alkalinity of a substance
- litmus paper
- universal indicator
- PH probe
107
chem: what litmus paper is used to determine alkalinity
red litmus paper turns blue
108
chem: what litmus paper is used to determine if a substance is acidic
blue litmus paper turns red
109
chem: define titration
it is a technique that measures the volumes of acid and alkali solutions needed in a neutralization reaction
110
chem: define a strong acid
it is an acid that when in water fully ionises, all of the acid breaks up to form H+ ions
111
chem: what is a weak acid
it is an acid that when in water does not fully ionise, most are weak
112
chem: what is the equation for fermentation (yeast)
glucse -> ethanol + carbon dioxide
113
chem: what is a limiting reactant and how do you find it
it is the reactant that is completely used up first, the reaction stops when this happens, you find it by finding the reactant with the lowest moles
114
chem: if i fill 3 ballons with gas, one with 1 mole methane, one with 1 mole argon and one with 1 mole chlorine, which baloon will be the largest
they will all be the same size because at the same temperature and pressure one mole of any gas will have the same volume because it is the same amount of atoms.
115
chem: for titrations what is the range for concordant results
0.1 cm3
116
chem: if a there is 20 cm3 of liquid in my measuring tube and it has an uncertanty of +/-1 cm3, write lower and upper bounds for the amount of liquid
19 < l < 21
117
chem: Name three factors that make the percentage yield of a reaction less than 100%?
reaction is incomplete
waste products
side reactions
118
chem: what makes a chemical cell have more voltage/potential difference
more difference in reactivity will result in more voltage
119
chem: what happens to a chemical cell when you change the electrode
changing the electrode will change the reactions that happen at each electrode and so change the voltage
120
chem: what makes a chemical cell non - rechargable
irreversable chemical reactions take place at the elctrodes, as soon as the one of the reactants has run out electrisity cannot be produced.
121
chem: what makes a chemical cell rechargable
connection to an electric current reverses the reactions that occured to produce electrisity and recharges the cell
122
chem: what are fuel cells
they produce electrical energy by reacting a fuel (often hydrogen) with oxygen (e.g. from the air), when this happens a current is produced and a current will continue to be produced unitll the fuel runs out.
123
chem: what are the pros of fuel cells
- they have high efficiency
- they can produce less polution
- they are reliable as they have no moving parts
- they can be compact
124
chem: hydrogen fuel cells vs petrol, which has a higher energy per gram
hydrogen fuel cells
125
Chem: if a change of state happens and the temperature increases during the change of state what can we say about the substance
It is impure or a mixture
126
Chem: what is Rf in chromatography
It is the retention factor, its equation is distance traveled by dye(compound) / distance traveled by solvent
127
Chem: what is chromatography used for
It is used to distinguish between pure and impure substances
128
chem: why are small covalent molecules liquids or gasses at room temperature
- when molecules melt or boil it is the intermolecular forces that break
- these intermolecular forces are weak in simple covalent substances
129
chem: define alloys
they are combinations of 2 or more elements when one of them is a metal
130
chem: what is the difference between metals and alloys (**in properties**)
alloys are:
- stronger than metals
- contain other elements
- harder
- the layers in alloys are distorted
131
chem: what are the 2 types of conducter
- heat - delocalized electrons can carry heat
- electrical
132
chem: what is an allotrope and what is an example of one
- it is a different form or an element
- diamond is an allotrope of carbon
133
chem: what are the properties of diamond
- they are hard, they have lots of covalent bonds
- covalent bonds, every carbon atom is bonded to 4 others
- diamond has not delocalized electrons that can conduct a charge
- high melting and boiling point, it is very hard to break strong covalent bonds, hence high melting and boiling point
134
chem: what are the properties of graphite
- covalent bonds, each carbon atom is bonded to 3 others
- soft, there are layers to graphene that are able to slide over one another
- conductivity, each carbon atom forms 3 bonds, there is a delocalized electron for every carbon atom
135
chem: what are the properties of graphene
- conducts, delocalized electron can conduct
- graphene is light but strong because it is one layer thick
136
chem: what is a fullerine
they are allotropes of carbon that take hollow structures
137
chem: what is the first spherical fullerene called
it is called buckminsterfullerene (C60)
138
chem: what are some uses of buckminsterfullerenes
- catalysts
- lubricants
- as vehicles for transporting drugs into our bodies
139
chem: what are some properties of cylindrical fullerenes
- strength, strong covalent bonds
- conductivity
140
chem: describe cylindrical fullerenes
they are called carbon nanotubes and take the shape of a cylinder, they are often called molecular wires because they have a tiny diameter but are very long
141
chem: what are some uses of cylindrical fullerenes
- electronics
- nanotechnology
- for strengthening materials
142
chem: what are clumps of particles
matter often 'clump' up into small particles, the size of the clump gives it a different name:
- nanoparticles
- fine particles
- coarse particles
143
Chem: why, when tennessine was discovered in 2010, was it not recognised as a new element until 2015
Because the discovery of the element must be repruducable
144
Chem. what is the dependent variable
The one that the depends on the other variables
145
Chem: how to calculate overall energy change
Energy in bonds of reactants - energy in the bonds of products = overall energy change
Energy in - energy out = overall energy change
146
Chem: why do alloys conduct electricity worse than pure metals
Because the different elements in the alloy interrupt the lattice structure and make it harder for the electrons to move through the structure
147
Chem: what equation links moles, volume and concentration
Conc = moles / volume
148
Chem: explain how aluminium conducts electricity in terms of electrons
- delocalised electrons
- they can carry a charge
- they flow through the substance
149
chem: who came up with the plum pudding model, when?
JJ thompson, 1897
150
chem: who thought the atom was a nucleus with all of the posotive charge in the center and a cloud of neagtive charge, when
Ernest Rutherford, 1909
151
chem: who came up with the idea that electrons were in shells with orbits, when?
Niels Bohr, 1913
152
chem: who came up with the idea of protons, when
Rutherford, 1919
153
chem: who came up with the idea of neutrons
James Chadwick, 1932
154
chem: what are all of the transition elements
they are metals
155
chem: what are the properties of the alkali metals
- low dencity
- relativly low melting point
- soft, can be cut with a scalpel
- very reactive
156
chem: what is a giant ionic latice
it is an ionic structure with an underined amount of ions
157
chem: what are the properties of giant ionic lattices
- each positive ion is surrounded by a negative ion
- they are 3d structures
- very strong forces of attraction between pos and neg ions (**electrostatic forces of attraction**) which hold the ions in place
- very high melting and boiling points
158
chem: what are electrostatic forces
they are the forces between posotive and negative ions
159
chem: what can ionic compounds do when molten or dissolved, how?
they can conduct electrisity, remember that it is the ions that move not the electrons
160
Chem: in diamond, graphite and graphene what are the bonds
covalent
161
chem: what is the main property of nanoparticles
very high surface area to volume ratio
162
chem: what is the empirical formula
The empirical formula of a compound is the simplest, whole number ratio of atoms of each element in a compound,
163
chem: what is an exothermic reaction profile
164
chem: what is an endothermic reaction profile
165
chem: what is the structure of a hydrogen fuel cell
166
chem: what type of equation shows electrons
Half equations
167
chem: what is the reactivity series
168
chem: what is the equation for moles involving Mr
Moles = mass / Mr
169
Chem: what are 4 types of Exothermic reactions
- neutralisation
- combustion
- oxidation
- hand warmer
170
Chem: what are the 3 types of endothermic reactions
- thermal decomposition
- citric acid + sodium hydrocarbonate
- sport injury packs
171
Chem: what are the 2 requirements for a reaction to occur
- collisions
- activation energy
172
Chem: through bond energy how do you find if a reaction is Exothermic or endothermic
You can subtract the bond energy from products and reactants, if the answer is pos then it is endothermic and if the answer is negative then it is Exothermic
173
Chem: how many electrodes are required to create a chemical cell
2
174
Chem: what is a battery
It is multiple cells joined in series
175
Chem: what are the 2 parts of chemical cells
Electrodes and electrolytes
176
Chem: how do you find the voltage of a battery
It is the sum of the voltages of the individual cells
177
Chem: what is the reason for a battery not being usable any more
Chemicals in the battery running out
178
Chem: what happens to the boiling point of water when it is impure
It is nit 100 degrees and will boil over a range of possible temperatures based on how impure and what the impurities are
179
Chem: what is limewater an aqueous solution of
Calcium hydroxide
180
Chem: what type of compounds do transition metals form
Coloured
181
Chem: where do delocalised electrons in metals come from
The outer shell, bonding of metals remember and put in answer
182
Chem: what type of bonds in metals give them high melting points
Strong metallic bonds
183
Chem: what are metallic bonds
They are the bonds between the ions and the delocalised electrons
184
Chem: why are pure metals soft and malliable
Because they have layers that can slide over one another
185
Chem: why are alloys harder than pure metals
Because the other elements in the structure interrupt it and impeded the layers from sliding over one annother
186
Chem: what is the method by which titrations are performed
In a titration one solution of a known concentration is added slowly to another solution with a know volume but unknown concentration, in order to find it
187
Chem: what is the table you use to perform titration calculations
188
Chem: what is the equation used by titrations using **only** moles and volume
189
Chem: what can acids be neutralised by
Alkalies, (soluable baces)
190
Chem: what are some examples of exothermic reactions
- neutralisation
- combustion
- oxidation
- hand warmers
191
Chem: what are some examples of endothermic reactions
- thermal decomposition
- citric acid + baking soda
- sport injury packs
192
Chem: what is required for simple electrical cells
2 electrodes
193
Chem: what is the stationary phase in paper chromatography
The paper
194
chem: what are coarse particles often referred to as
dust
195
Chem: what conclusions did the alpha scattering experiment disocver
- the mass of an atom was concentrated in the centre of the atom
- the nucleus was charged
196
Chem: how was the nucleus discovered
The alpha particle scattering experiment
197
chem: what was the nuclear model of the atom and what did it introduce
Electrons orbit the nucleus in energy levels (specific distances)
198
chem: what is the approximate radius of the atom
0.1 nm
199
Chem: what is the radius of the nucleus of the atom
The radius of the nucleus is less than 1/10000 of that of the atom (0.1 nm)
200
Chem: where is almost all of the mass of the atom
The nucleus
201
Chem: what is group 0
They are the noble gasses
202
Chem: what are the properties of group 0 (noble gasses)
They are unreactive as they have a full outer shell of electrons (8 electrons in the outer shell of all but the 2 in helium) and are also **gasses**, the boiling points of the noble gasses increase with increasing size (Mr)
203
Chem: how can a halogen be replaced in its salt
A more reactive halogen can replace a less reactive one from an aqueous solution of its salt (consider how to add another flashcard)
204
205
Chem: what are the properties of group 7, going down the group
- down the group higher melting and boiling point
- reactivity decreases
206
Chem: what are the 2 types of covalent bonding and what is an example of each
- simple covalent - oxygen
- giant covalent - diamond
207
Chem: what does a dot and cross diagram for ammonia look like
208
chem: what are the limitations of dot and cross and ball and stick diagrams
They fail the illustrate the 3D arrangement of atoms and their electrons orbits
209
Chem: what are the limitations of 3d models of ionic compounds
It is not to scale and gives no indication of the forces or transfer of electrons
210
Chem: what are some limitations of a 2d representation of ionic bonding
It only represents one layer of the structure
211
Chem: what are the limitations of these models of states of matter
It does not show the forces and all of the particles are represented as spheres
212
Chem: why do ionic compounds conduct when they are molten or dissolved
Because the ions are free to move
213
Chem: why are metals malliable
Because they are in layers that allow them to be bent and shaped
214
Chem: why are metals made into alloys
Alloys are much harder
215
chem: in diamond how many bonds do each carbon atom form and what properties does this give the structure
- 4
- increased melting and boiling point (I think adi check and remove when done so)
216
Chem: in graphene how many bonds do each carbon atom form and what structure do they take and what properties does this give the structure
- 3, they form hexagonal rings, there are no bonds between the layers
- conductivity
217
Chem: why is graphene similar to metals
Because it has delocalised electrons (they can carry a charge)
218
Chem: what do graphenes properties make it useful for
Composites and electronics
219
Chem: what is the mass of one mole of any substance equal to
It is numerically equal to its relative formula mass
220
221
Chem: what is Avogadro's constant
It is 6.02 X10^23 and is the number of atoms in a mole
222
Chem: what is the volume of 1 mol of any gas at room temperature and pressure (20 degrees and 1 atmos)
24 dm3
223
Chem: what is room temperature and pressure
- 20 degrees
- 1 atmosphere
224
Chem: what happens to some metals when they react with acids
They produce salts and hydrogen
225
Chem: what are redox reactions
It is a reaction where reduction and oxidation occur, displacement is one example, some of the atoms loose electrons and some gain them
226
Chem: what is the range for the PH scale
0 to 14
227
Chem: what are some examples of strong acids
- hydrochloric acid
- nitric acid
- sulfuric acid
228
Chem: what are some examples of weak acids
- ethanoic acid
- citric acid
- carbonic acids
229
Chem: what is the overall energy change of a reaction
It is the difference between the sum of the energy needed to break the bonds in the reactants and the sum of the energy released when bonds in the products are formed
230
Chem: what is an exothermic reaction in terms of the overall energy change
The energy released from forming new bonds is greater than the activation energy (energy required to break the bonds in the reactants)
231
Chem: what is an exothermic reaction in terms of the overall energy change
The energy released from forming new bonds is less than the activation energy (energy required to break the bonds in the reactants)
232
Chem: what 2 factors affect the voltage of a chemical cell
Electrodes and electrolytes
233
Chem: what is a simple way of making a chemical cell
Connecting 2 different metals in contact with an electrolyte
234
Chem: what type of chemical creates non rechargeable batteries
Alkaline batteries
235
Chem: what does connecting cells in series accomplish
Increasing the voltage of the battery
236
Chem: how are re-usable cells recharged
They are recharged when an external current is supplied
237
Chem: how can soluble salts be made form acids
They can be made from acids by reacting them with insoluble substances such as metals, metal oxides, hydroxides or carbonates, the solid is added until no more acid reacts and then the excess solid is filtered off to produce a solution of the salt
238
Chem: how can soluble salts solutions be made into solid salts
They can be crystallized
239
Chem: what happens when some acids react with metals
Salts and hydrogen are produced
240
241
Chem: what is an element that reacts to form a positive ion
A metal
242
Chem: what is an element that does **not** react to form a positive ion
A non-metal
243
Chem: how were elements arranged before protons neutrons and electrons were discovered
Scientists arranged elements by their weights
244
Chem: what did Mendeleev do to the periodic table that made it better
He left spaces for elements he thought had not yet been discovered, he also changed the order of some elements, so they were not ordered by atomic weights, elements with the properties that Mendeleev predicted filled the gaps and knowledge of isotopes explained why atomic weights were not always correct.
245
Chem: what is the relative atomic mass
It is an average value that takes into account the abundance of each isotope of the elements
246
Chem: what is the mass of an electron
It is **very small**
247
Chem: what are the elements in group 0 of the periodic table called
The noble gasses
248
Chem: what are the properties of the noble gasses
- they are unreactive as they have a full outer shell, eight for all but helium which has **2**
- with growing atomic mass, going down the group, the boiling points of the gasses increase
249
Chem: what are the properties of small molecules
- relatively low melting and boiling points
- do not conduct as they have no overall charge
- when they melt and boil it is not the covalent bonds but the intermolecular forces that are overcome
250
Chem: what is the shape fullerenes are baced upon
Hexagonal rings of carbon atoms, but they can also have rings with 5 or 7 carbon atoms
251
Chem: when the side of a cube decreases by a factor of 10 what happens to the surface area to volume ratio
It increases by a factor of 10
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Chem: what are spherical fullerenes also known as
buckyballs
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Chem: why can nanoparticles have different properties to those of the same material
Because of their high surface area to volume ratio, they might be more useful as less of them might be needed to be as effective as less "nano" particles of the same type
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Chem: what can nanoparticles be used for
- drug delivery
- sun creams
- antimicrobial coatings
- catalysts
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Chem:
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Chem: what type of metals are found in teh earth not as an ore
Un reactive ones like gold
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Chem: what happens in a neutralisation reaction
Hydrogen ions react with hydroxide ions to produce water
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Chem: what is the process to calculate the limiting reactant of a substance
259
Chem: when drawing a diagram of electrolysis what must you remember to draw
- **battery, circuit**
- electrodes
- electrolyte
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Chem: what is the reactivity series you have to remember
261
Chem: what is an electrolyte
When an ionic compound is melted or is dissolved in water the ions are free to move within the liquid or solution, these liquids can conduct and are called electrolytes
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Chem: what happens when an electric current is passed through an electrolyte
- the ions are free to move to the electrodes
- pos ions move to the negative electrode and vice versa
- ions are **discharged** at the electrodes and become elements, this is electrolysis
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Chem: when is electrolysis used to extract metals from their ores
When the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon, **large amounts of energy are used to** melt the metal and to produce the electrical current
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Chem: how can some metals more reactive than carbon be extracted from their ores
By melting them end electrolysing them
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Chem: how is aluminium manufactured with electrolysis
A molten mixture of aluminium oxide and cryolite is electrolysed with carbon as the positive electrode (anode)
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Chem: what are stronger intermolecular forces of attraction or covalent bonds
Covalent bonds
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Chem: why are mixture used as an electrolyte in aluminium elecrtolysis
Aluminium oxide is insoluble in water, so it must be molten to act as an electrolyte. However, the melting point of aluminium oxide is high. A lot of energy must be transferred to break its strong ionic bonds, and this is expensive. To reduce costs, powdered aluminium oxide is dissolved in molten cryolite.
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Chem: why in aluminium electrolysis why must the positive electrode be constantly replaced
At the positive carbon electrode carbon dioxide is formed, so the electrode must be replaced frequently
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chem: what is used to measure the volumes of acid and alkali solutions that react together in a titration reaction
a suitable indicator, check
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Chem: what is this model
The nuclear model
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Chem: what is this model
Bhor
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Chem: what is this model of the atom
Dalton
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Chem: what is daltons model
It is the model of the atom where atoms are tiny spheres that cannot be broken up
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Chem: an indicator used in titrations
Phenolphthalein indicator
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Chem: why does rate of reaction increase with temp
The temp increases, the particles have more ke and so there is a greater freq of collisions, so greater rate of reaction increase
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Chem: what are the colours for phenolphthalein
Colourless in acid and pink in base
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Chem: methyl orange indicator colours
Red acid yellow bace
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Chem: what empirical formula
279
Chem: why do ionic compound shave high melting and boiling points (same for giant covalent)
- **many/lots** of strong ionic (/covalent) bonds
- required lots of energy to overcome them
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Chem: why can / not ionic compounds conduct / not when molten or dissolved / solid
Ions in the ionic compounds cannot move and carry a charge when solid but can when liquid or dissolved
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Chem: what is ductile
It can be stretched into a wire
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Chem: what is malleable
It is where a material is shapable
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Chem: why is a metal mailable/ductile
- Layers can slide over one another
- layers are regular and uniform (so it is easier for them to slide over one another, unlike and alloy)
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Chem: what are polymers
- they are long chains of covalently bonded atoms
- their properties depend on monomers and intermolecular forces
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Chem: what does it mean for something to be stronger than something else
286
Chem: make cards on did properties of elements
