C4 Flashcards
(151 cards)
1
Q
What are atoms?
A
Tiny particles of matter that make up everything in the universe
2
Q
At the start of the 19th century what did John Dalton describe atoms as?
A
Solid spheres and the different spheres made up the different elements
3
Q
In 1897 what did J J Thomson conclude from his experiment?
A
That atoms weren’t solid spheres. His measurements of charge and mass showed that an atom must contain even smaller, negatively charged particles - electrons.
This was known at the plumb pudding model.
4
Q
Who showed that the ‘plumb pudding model’ was wrong?
A
Ernest Rutherford, and his students Hans Geiger and Ernest Marsden.
They conducted the famous gold foil experiment.
5
Q
What is the famous gold foil experiment?
A
They fired positively charged particles at an extremely thin sheet of gold. From the plumb pudding model, they were expecting most of the particles to be deflected by the positive ‘pudding’ that made up most of the atom. In fact, most of the particles passed straight through the gold atoms, and a very small number were deflected backwards. so the plumb pudding model couldn’t be right.
6
Q
What new theory did Rutherford come up with?
A
The theory of the nuclear atom.
In this there’s a tiny, positively charged nucleus at the centre, surrounded by a ‘cloud’ of negative electrons - most of the atom is empty space.
7
Q
Most scientists realised that the ‘cloud’ around the atom would be attracted to the nucleus causing the atom to collapse. What did Bohr decide instead?
A
That the electrons can only exist in fixed orbits, or shells, and not anywhere between. Each shell had a fixed energy.
It contained a nucleus in the middle and was pretty close to the structure we have today.
8
Q
Give 4 facts about the nucleus
A
It’s in the middle of the atom
It contains protons and neutrons
It has a positive charge because of the protons
Almost the whole mass of the atom is concentrated in the nucleus
9
Q
Give 5 facts about electrons
A
They move around the nucleus in electron shells
They’re negatively charged
They’re tiny, but they cover a lot of space
The volume of their orbits determines the size of the atom
Electrons have virtually no mass
10
Q
What are protons?
A
Heavy and positively charged
11
Q
What are neutrons?
A
They are heavy and neutral
12
Q
What are electrons?
A
Tiny and negatively charged
13
Q
What is the number of protons equal to in an atom?
A
Electrons
14
Q
What charge do neutral atoms have?
A
No charge
15
Q
Wanna hear a joke…? :P
A
A neutron walks into a bar and asks how much for a drink.
The bar man says, “For you, no charge.”
16
Q
Why are atoms neutral?
A
The charge on the electrons is the same size as the charge on the protons but opposite - so the charges cancel out
17
Q
What is ‘The Mass Number’?
A
The top number next to the symbol on the periodic table.
It is the total number of protons and neutrons in the atom
18
Q
What is ‘The Atomic Number’?
A
The bottom number next to the symbol on the periodic table.
It is the number of protons in the atom
19
Q
How can you get the number of neutrons in an atom?
A
By subtracting the atomic number from the mass number
20
Q
Which number is always the biggest number when looking at an atom on the periodic table?
A
The mass number
21
Q
What is the ‘relative atomic mass’?
A
The mass number, the top number when looking at an atom on the periodic table
22
Q
What are elements?
A
Substances made up of only one type of atom.
23
Q
How many elements are there?
A
100 ish, more are still being discovered
24
Q
What does the modern periodic table show the elements in order of?
A
Ascending atomic number
25
What do all of the atoms in the same columns share?
Similar properties
26
What are the vertical columns in the periodic table called?
Groups
27
What does the group of an atom correspond with?
The number of electrons on its outer shell
28
How many electrons do group 1 elements have on their outer shell?
1
29
How many electrons do group 7 elements have on their outer shell?
7
30
What are rows in the periodic table called and what does each new row represent?
Periods, each new period represents another full shell of electrons
31
What are isotopes?
Different forms of the same element, which have the same number of protons but a different number of neutrons.
32
What are the similarities and differences between atomic numbers and mass numbers in isotopes?
Isotopes have the same atomic number but different mass numbers
33
Give an example of a popular pair of isotopes
Carbon-12 and carbon-14
34
In the 1800's what was the only thing they could measure?
Relative atomic mass
35
What did Dobereiner do to try and organise the elements?
Put them in groups of three called triads. The average relative atomic mass of the top and bottom one was equal to the relative atomic mass of the middle one
36
What was the first good effort of trying to organise the atoms called?
Newlands' Law of Octaves
37
Give some problems of Newlands' Law of Octaves
The pattern broke down on the third row
He left no gaps for the elements that were yet to be discovered
His groups contained elements that didn't have similar properties
He mixed up metals and non metals
38
Who's theory do we still use for our periodic table today?
Dmitri Mendeleev, he left gaps where he thought elements should be and when new ones were found they fitted the pattern. Yay!
39
What are the three electron shell rules?
Electrons always occupy shells
The lowest energy levels are always filled first
Only a certain number of electrons are allowed in each shell.
40
How many electrons are allowed in the first shell?
2
41
How many electrons are allowed in the first and second shells?
8 in each
42
What is electron configuration?
How the electrons occupy the shells around an atom
43
What is the electron configuration for nitrogen if the atomic number is 7?
2.5
44
What is the electron configuration for aluminium if the atomic number is 13?
2.8.3
45
What can you use electron configuration to work out?
The period, group and atomic number of an element
46
What is an ion?
An atom which has lost or gained electrons causing it to become positively or negatively charged
47
What happens in ionic bonding?
Atoms lose or gain electrons to form charged particles (or ions) which are then strongly attracted to one another (because of the attraction of opposite charges, + and - )
48
How many electrons to the group 1 elements have on their outer shells and why does this make them very reactive?
They only have one, the main aim for an atom is to have a full outer shell so they are keen to get rid of that extra electron and turn into a positive ion.
49
What do positive ions want to bond to?
Negative ions
50
What do group 6 or 7 elements want to do?
Gain one or two electrons
51
What do group 7 elements become when they gain an extra electron?
A negative ion
52
What do ionic compounds form?
Giant ionic lattices
53
Give 3 properties of ionic compounds
The ions are closely packed together
The ions are not free to move meaning they don't conduct electricity in solid form
There are very strong chemical bonds between all the ions
54
Give two names of giant ionic structures
Magnesium oxide
| Sodium chloride
55
Give two properties of both magnesium oxide and sodium chlordie
They both have high melting points
| They both have high boiling points
56
Why do magnesium oxide and sodium chloride both have high melting and boiling points?
Because they have very strong attractions between oppositely charged ions in the giant structures
57
Which has a higher melting point:
Mg2+ + O2-
or
Na+ + Cl-
Mg2+ + O2-
This is because the forces are double the strength of the other one, so the attraction between them is harder to overcome
Also the O2- ions are smaller than Cl- ions, so the ions in MgO can pack together more closely, this also makes the attraction between them harder to overcome.
58
What happens when MgO melts?
The ions are free to move and they'll conduct electricity
59
When metals form ions what do they do?
They lose electrons to form positive ions
60
When non-metals form ions what do they do?
They gain electrons to form negative ions
61
K+ + Cl- ---> ?
KCl
62
2K+ + O2- ---> ?
K(little 2) O
63
What are covalent bonds?
When two atoms share electrons so that their outer shells are complete
64
How many more electrons do hydrogen atoms need to have a complete outer shell? Because of this, how many covalent bonds do they need to form?
one more
| This means they only need to form one covalent bond between them to become H2
65
How many electrons do chlorine atoms need to complete their outer shells, how many covalent bonds do they form with other atoms and what does it form after?
one
one
Cl2
66
How many electrons are on the outer shell of a carbon atom, how many covalent bonds form with it and what does it form after?
4
4
Methane, CH4
67
How many more electrons does an oxygen atom need on its outer shell, how many covalent bonds does it from with other atoms and what does it make after?
2
2
H2O
68
How many more electrons does a carbon atom need on its outer shell, how many covalent bonds does it form with oxygen and what does it create afterwards?
4
2 - because oxygen shares two electrons per covalent bond
CO2
69
What do substances formed from covalent bonds usually have?
simple molecular structures
This is because the atoms within the molecules are held together by very strong covalent bonds, but in contrast the forces of attraction between these molecules are very weak
70
What is a result of feeble intermolecular forces?
The melting and boiling points are very low, this is because the molecules are very easily parted form each other
71
What are most molecular substances in the form of at room temperature?
Gases or liquids
72
Why don't most molecular substances conduct electricity?
There are no free electrons or ions
73
What are group 7 elements called?
Halogens
74
What is group 7 made up of?
```
Fluorine
Chlorine
Bromine
Iodine
Astatine
```
75
What happens as you go down group 7 in the periodic table?
They become less reactive
This is because there's less inclination to gain the extra electron to fill the outer shell when its further out from the nucleus.
Also the melting points and boiling points of them increase as you go down the group 7 elements
76
What is chlorine like at room temperature?
Fairly reactive
Poisonous
Dense green gas
Low boiling point
77
What is bromine like at room temperature?
Dense
Poisonous
Orange liquid
78
What is iodine like at room temperature?
A dark grey crystalline solid
| High boiling point
79
What is reduction?
The gain of electrons
80
What does a halogen molecule turn into when it gains electrons?
A halide ion
81
Halogens react vigorously with alkali metals to form what?
Salts called 'metal halides'
82
2Na + Cl2 ---> ?
| Sodium + Chlorine ---> ?
2NaCl
| Sodium chloride
83
2K + Br2 ---> ?
| Potassium + Bromine ---> ?
2KBr
| Potassium bromide
84
What can more reactive halogens do?
Displace less reactive ones
85
What can chlorine displace?
Bromine and iodine from a solution of bromide or iodide
86
What can bromine displace?
Iodine
87
Chlorine + Potassium iodide --->
Iodine + Potassium chloride
88
Chlorine + Potassium bromide --->
Bromine + Potassium chloride
89
What are the group 1 metals called?
Alkali metals
90
What happens as you go down group 1?
They become more reactive
91
What are the physical properties of the group 1 elements?
Low melting point
Low boiling point
Low density
Very soft
92
What bonds to group 1 elements from?
Ionic ones only
93
What is oxidation?
The loss of electrons
94
What happens when you put group 1 elements in the water?
They react very vigorously and produce hydrogen gas
95
What do sodium and potassium do in the heat of the reaction?
Melt
96
What are the first 5 group 1 elements?
```
Lithium
Sodium
Potassium
Rubidium
Caesium
```
97
2Na H2O ---> ?
| Sodium + water ---> ?
2NaOH H2
| Sodium hydroxide + Hydrogen
98
What do all the alkali metals form when they react with water?
Their symbol and then OH
Lithium produces LiOH
Potassium forms KOH
(they also all produce H2 as a product too)
99
How can you test to see which alkali metal you have?
Dip a wire loop into some hydrochloric acid to clean and moisten it
Put the loop into a powdered sample of the compound to be tested, then place the end in a blue bunsen flame
Alkali metal ions will give pretty coloured flames - the colour of the flame tells you which alkali metal is present.
100
What colour flame does lithium produce?
Red
101
What colour flame does sodium produce?
Yellow/orange
102
What colour flame does potassium produce?
Lilac
103
What structure do all metals have?
A crystal structure
104
What are metallic bonds?
The bonds allow the outer electron(s) of each atom to more freely. This creates a 'sea' of delocalised electrons throughout the metal.
105
Give ___ properties of metals?
```
Very hard, dense and lustrous (shiny)
They have a high tensile strength
They're malleable
High melting points and boiling points
Good conductors of heat and electricity
```
106
In what conditions does the strength of a metallic bond decrease?
When the atomic radius increases
107
Give the properties of a saucepan and the metal that they are made from
Good conductor of heat, doesn't rust easily
| Stainless steel - its cheap too
108
Give the properties of electrical wiring and the metal that is used for them
Good conductor of electricity, easily bent
| Copper. One of the best conductors around
109
Give the properties of aeroplanes and the metal used for them
Low density, strong, doesn't corrode
| Aluminium. Titanium is sometimes used, but it's a lot more expensive
110
Give the properties of bridges and the metal used for them
Strong
| Steel - this is mostly iron, but it's got a little bit of carbon in it, which makes it a lot less brittle
111
At what temperatures are some metals super conductors?
Very low temperatures
112
What is electrical resistance?
Where metals that conduct electricity have the draw backs of losing their power through heat as they are used
113
Do superconductors have electrical resistance?
NO
114
What can you make using super conductors?
Power cables that transmit electricity without any power loss
Really strong electromagnets that don't need a constant power source
Electronic circuits that work really fast, because there's no resistance to slow them down
115
What's the catch of superconductors?
They only start superconducting at less than -265 degrees C
| Getting things what cold is very hard and very expensive
116
What are scientists trying to do regarding super conductors?
They are trying to develop them to work at room temperature. So far they've got up to -135 degrees C which is much cheaper but the ideal is 20 degrees C
117
What are the metals in the middle of the periodic table?
Transition metals
118
What do transition metals make?
Googd catalysts
119
What is an iron catalyst used for?
Making ammonia in the Haber process
120
What is a nickel catalyst used for?
The hydrogenation of alkenes (e.g. to make margerine)
121
What colours are Iron (II) compounds usually?
Light green
122
What colours are Iron (III) compounds usually?
Orange/brown
123
What colours are copper compounds usually?
Blue
124
What is thermal decomposition?
The breaking down of something with heat
125
Can transition metals thermally decompose?
Yes
126
What do transition metal carbonates always include some of?
CO3
127
What do transition metal oxides break down into when they are thermally decomposed?
They make a metal oxide and carbon dioxide.
| This usually results in a colour change
128
Give the word and symbol equation for the thermal decomposition of copper (II) carbonate
Copper(II) carbonate ---> Copper oxide + carbon dioxide
| CuCO3 CuO CO2
129
What is a precipitation reaction?
Where two solutions react and an insoluble solid forms in the solution
130
What do transition metal compounds form when they react with sodium hydroxide?
An insoluble hydroxide with then precipitates out
131
CuSO4 + 2NaOH ---> ?
| copper(II) sulphate + sodium hydroxide ---> ?
Cu(OH)2 Na2SO4
| copper(II) hydroxide + sodium sulphate
132
What is the ionic equation for the precipitation reaction of coper sulphate and sodium hydroxide?
Cu2+ + 2OH- ---> Cu(OH)2
133
How can you test for transition metal ions?
Using precipitation reactions
134
What transition metal hydroxide produces a blue solid?
Copper (II) hydroxide
135
What transition metal hydroxide produces a grey/green solid?
Iron (II) hydroxide
136
What transition metal hydroxide produces a orange/brown solid?
Iron (III) hydroxide
137
What happens if you add sodium hydroxide to an unknown soluble salt?
The colour that is produced is an indicator of what the unknown soluble salt is. (if its orange/brown the salt will be iron (III) hydroxide)
138
Where do we get our water from in the UK?
Surface water: lakes, rivers and reservoirs (artificial lakes) But these start to run dry during the summer months.
Groundwater: aquifers (rocks that trap water underground)
139
What are water resources limited by?
Annual rainfall
140
What are the three stages of water purification?
Filtration - a wire mesh screens out large twigs and then gravel and sand beds filter out any other solid bits
Sedimentation - iron sulphate or aluminium sulphate is added to the water, which makes fine particles clump together and settle at the bottom
Chlorination - chlorine gas is bubbled through to kill harmful bacteria and other microbes
141
What various pollutants are still in our tap water?
Nitrate residues (from excess fertiliser 'run off' into rivers and lakes
Lead compounds from old lead pipes
Pesticide residues from spraying too near to rivers and lakes
142
What is wrong with water distillation?
It needs lots of energy
It's really expensive
Not practical for producing large quantities of fresh water
143
How can you test for sulphate ions in water?
Using Barium Chloride
1. add some dilute hydrochloric acid to the test sample
2. Then add 10 drops of barium chloride solution
3. If you see a white precipitate, there are sulphate ions in the sample
144
Give an example of where potassium sulphate is present in the sample of water
barium chloride + potassium sulphate ---> barium sulphate + potassium chloride
(BaCl2 + K2SO4 ---> BaSO4 + 2KCl)
145
How can you test for halide ions in water?
Using silver nitrate
1. add some dilute nitric acid to the test sample
2. then add 10 drops of silver nitrate solution
3. if halide ions are present a precipitate will form
146
When testing for chloride ions in water what colour precipitate will form?
white
147
When testing for bromide ions in water what colour precipitate will form?
cream
148
When testing for iodide ions in water what colour precipitate will form?
pale yellow
149
Silver nitrate + sodium chloride ---> ?
| AgNO3 NaCl
Silver chloride + sodium nitrate
| AgCl NaNO3
150
Silver nitrate + sodium bromide ---> ?
| AgNO3 NaBr
Silver bromide + Sodium nitrate
| AgBr NaNO3
151
Silver nitrate + sodium iodide ---> ?
| AgNO3 NaI
Silver iodide + sodium nitrate
| AgI NaNO3
