GCSE Chemistry C2 Edexcel
From the CGP Revision Guide
5.0 / 5 based on 7 ratings
- Created by: johnpithers
- Created on: 08-06-14 14:37
Describe the nucleus in the atom?
It's in the middloe of the atom, it contains protons and neutrons, has an overall positive charge (because of protons), accounts for nearly all of the atoms mass, tiny compared to the atom as a whole
1 of 147
Describe the electrons in the atom?
They move around the nucleus, have a negative charge, tiny compared to nucleus but move around and cover alot of space, the size of their orbits determines how big the atom is, virtually no mass and occupy shells around the nucleus
2 of 147
What's a shell?
An energy level around the nucleus
3 of 147
How does the number of protons compare to the number of electrons?
They are the same
4 of 147
What charge do protons, neutrons and electrons have?
+1, 0 and -1
5 of 147
How does the number of neutrons relate to the number of protons/electrons?
It isn't fixed, but usually around the same number
6 of 147
What is the mass of protons, neutrons and electrons?
1,1 and 1/2000
7 of 147
What are the 5 electron shell rules?
Electrons always occupy shells, the shells closest to the nucleus are filled first, only 2 electrons in the first shell then 8 per shell, atoms are happier with a full outer shell, in most atoms the outer shell isn't full so they want to react
8 of 147
What part of the atom determines what element it is?
The number of protons
9 of 147
What's the atomic number?
How many protons/electrons in an atom
10 of 147
Which elements share atomic numbers?
None, each element has its own unique atomic number
11 of 147
What's the mass number?
The total number of protons and neutrons in the atom
12 of 147
Why doesn't mass number account for electrons?
They have a negligible mass
13 of 147
How do find the number of neutrons?
Mass number-atomic number
14 of 147
What are isotopes?
Isotopes are different forms of the same element which have the same number of protons but a different number of neutrons
15 of 147
What's relative atomic mass?
The average mass of the isotopes of an element
16 of 147
What's relative abundance?
How much there is of an isotope compared to the total amount of the element in the world
17 of 147
How do you calculate relative atomic mass?
(mass 1 x abundance 1)+(mass 2 x abundance 2)/(abundance 1+ abundance 2)
18 of 147
Who arranged the elements in groups?
Dmitri Mendeleev
19 of 147
When did Mendeleev first arrange elements in to groups?
1869
20 of 147
How did Mendeleev arrange elements into groups?
Grouped them according to their properties in vertical groups
21 of 147
Why were the gaps in Mendeleev's table clever?
They predicted the properties of undiscovered elements
22 of 147
3 examples of elements found that fit Mendeleev's gaps?
Scandium, gallium and germanium
23 of 147
Where are metals and non metals on the periodic table?
On opposite sides
24 of 147
What are the rows in the periodic table called?
Periods
25 of 147
Describe how periods relate to the periodic table?
The elements are arranged in order of increasing atomic number along each period, the period number is the same as the number of shells (period 3=3 shells), element properties change along a period
26 of 147
What are the vertical columns in the periodic table called?
Groups
27 of 147
Describe how groups relate to the periodic table?
Elements in the same group have similar properties, group number is equal to number of electrons in the outer shell (group 2=2 electrons on outer shell, element properties change gradually down a group
28 of 147
What is ionic bonding?
Transfer of electrons to form charged atoms called ions
29 of 147
What are charged atoms called?
Cations (positive) and anions (negative)
30 of 147
Why are ionic bonds strong?
The attraction of opposite charges
31 of 147
What do metals do in ionic bonding?
Give away one or two electrons to have a full outer shell, they become cations after this
32 of 147
What do non metals do in ionic bonding?
Gain one or two electrons to have a full outer shell, they become anions after this
33 of 147
Which 4 groups are most likely to form ions?
1,2,6 and 7
34 of 147
What are ionic bonds always between?
A metal and a non metal
35 of 147
What happens when cations join with anions?
They form ionic bonds
36 of 147
Describe the structure of ionic compounds?
Regular lattice structure, ions form a closely packed regular lattice arrangement
37 of 147
Why do ionic compounds have a lattice structure?
Ionic bonds are very strong electrostatic forces of attraction between oppositely charged ions
38 of 147
What are 2 properties of ionic compounds?
High melting/boiling point, conduct electricity when aqueous or molten
39 of 147
What's the reason for ionic compounds having the 2 named properties?
Very strong bonds between the ions means lots of energy is required to break the bonds, when aqueous the ions separate and are free to move and carry electric current, the same happens when they melt
40 of 147
What's the rule for naming compounds when 2 different elements combine?
The name ends in 'ide'
41 of 147
What's the rule for naming compounds when 3+ elements combine and one is oxygen?
The name ends in 'ate'
42 of 147
How do you work out a compound's formula?
Look at the charges of the ions involved and make the charge neutral
43 of 147
What are the rules of solubility for common salts of sodium, potassium and ammonium?
Always soluble
44 of 147
What are the rules of solubility for nitrates?
Always soluble
45 of 147
What are the rules of solubility for common chlorides?
Soluble except silver chloride and lead chloride
46 of 147
What are the rules of solubility for common sulfates?
Soluble except lead sulfate, barium sulfate and calcium sulfate
47 of 147
What are the rules of solubility for common carbonates and hydroxides?
Insoluble except for sodium, potassium and ammonium ones
48 of 147
Describe the practical to make insoluble salts?
Pick the right 2 soluble salts, mix solutions in a beaker, filter out precipitate, wash with distilled water, dry
49 of 147
An example of an insoluble salt?
Barium sulfate
50 of 147
How do you choose the right 2 salts?
They must be soluble, one's name beginning must be same as desired product, one's name end must be same as desired product
51 of 147
How is barium sulfate used?
X rays, shows up the gut, called a barium meal
52 of 147
What colour flame would sodium produce during a flame test?
Yellow/orange
53 of 147
What colour flame would calcium produce during a flame test?
Red
54 of 147
What colour flame would copper produce during a flame test?
Blue/green
55 of 147
Do flame tests work with compounds?
Yes
56 of 147
How do you perform a flame test?
Dip clean wire loop in compound and observe colour, with solids dip in hydrochloric acid to moisten so it sticks
57 of 147
What's a flame test used for?
To test for calcium, potassium, sulfate and copper ions
58 of 147
How do you test for carbonates?
Bubble gas through lime water, lime water turns milky if carbon dioxide is present, also can test solids because reacts with acid to form co2, acid+carbonate into salt+water+carbon dioxide
59 of 147
How do you test for sulfate ions?
Add dilute hydrochloric acid to barium chloride solution, a white precipitate of barium sulfate means original compound was a sulfate
60 of 147
How do you test for chloride ions?
Add dilute nitric acid to silver nitrate solution, a chloride gives a white precipitate of silver chloride
61 of 147
What is spectroscopy?
Similar to flame test, sample heated, light patterns looked at, each element produces different patterns
62 of 147
Describe spectroscopy?
Fast and reliable, can detect small amounts of an element, led to discovery of rubidium and caesium because they produced unseen patterns
63 of 147
What's covalent bonding?
Sharing pairs of electrons between atoms
64 of 147
What's it called when atoms make covalent bonds with others?
A molecule
65 of 147
What are the 2 kinds of covalent substance?
Simple molecular and giant molecular
66 of 147
Describe simple molecular covalent substances?
Atoms make strong covalent bonds to form molecules, forces of attraction between molecules is weak, low melting/boiling point because of weak molecular attraction, , most are gas/liquid at room temperature, don't conduct electricity (no ions)
67 of 147
Describe giant molecular covalent substances?
Similar to ionic lattices but without charged ions, atoms bonded by strong covalent bonds, high melting/boiling points, never conduct electricity (except graphite), insoluble in water
68 of 147
2 examples of giant molecular covalent substances?
Diamond and graphite, both made from carbon
69 of 147
What is the hardest natural substance?
Diamond
70 of 147
How is diamond formed?
Carbon atoms form 4 covalent bonds in a very rigid giant covalent structure, doesn't conduct electricity because there are no free electrons
71 of 147
Describe graphites ability to conduct electricity?
Each carbon atom only forms 3 covalent bonds which creates sheets of carbon atoms which can slide over each other (lubricant), layers held very loosely together, lots of spare electrons which can move so can conduct electricity
72 of 147
What does immiscible mean?
2 liquids cannot mix
73 of 147
How would you separate immiscible liquids?
2 liquids shaken then form layers, separating funnel, open tap to drain denser layer
74 of 147
How would you separate miscible liquids?
Liquids must have different boiling points, liquids condense at different temperatures for separate collection, fractional distillation
75 of 147
Describe how liquid air is fractionally distilled?
Filtered to remove dust, cooled to -200 to become miscible liquid mixture, during cooling water vapour condenses and is removed, carbon dioxide freezes and is removed, liquid heated slowly, gases move up then condense at different levels
76 of 147
What 2 gases come out together during fractional distillation of air?
Oxygen and argon
77 of 147
What's chromatography used for?
To identify substances
78 of 147
Describe paper chromatography?
Used to identify substances in a mixture, based on the fact that different substances go through water at different rates
79 of 147
Describe THE METHOD of paper chromatography?
Put spots of each mixture on a pencil baseline on filter paper, roll up paper then put in a beaker containing a solvent (eg water/ethanol), solvent moves up paper and moves samples, different chemicals form different spots, produce chromatogra
80 of 147
What's an RF value?
Ratio of distance travelled by substance compared to solvent
81 of 147
How do you calculate RF value?
Distance travelled by substance/distance travelled by solvent
82 of 147
Which industries are RF values used in?
Food and forensic science
83 of 147
Where are the metals on the periodic table?
Left and middle
84 of 147
What are 2 properties of most metals?
Conduct electricity well (eg used in wires), malleable meaning they can be bent or hammered into shapes (eg car bodies)
85 of 147
What are the 2 additional properties of transition metals?
High melting points, form very colourful compounds (eg used in hair dyes)
86 of 147
What 'gives' metals their properties?
Their structure, layers of electrons can slide
87 of 147
Describe the structure of metals?
Regular arrangement of atoms held together with metallic bonds, metallic bonds give metals a giant structure consisting of positive ions and free electrons because metallic bonds let outer electrons move freely, creates 'sea' of free electrons
88 of 147
What are the elements in group 1 called?
Alkali metals
89 of 147
How are alkali metals different from other metals?
Soft (can be cut with a knife), low melting points
90 of 147
What's a property of alkali metals?
They react vigorously in water to form hydroxides and make an alkaline solution (hence the name)
91 of 147
What's the trend of reactivity with alkali metals?
Further down the group they're more reactive because electrons are further form nucleus so weaker attraction so easier to get rid of, elements in group 1 get more reactive as atomic number increases
92 of 147
What do group 1 reactions with water produce?
Hydrogen gas which fizzes and can be identified by placing a lighted splint over the reaction and hearing a squeaky pop
93 of 147
What are the elements in group 7 called?
Halogens
94 of 147
What's true of all halogens?
They all have 7 electrons in their outer shell
95 of 147
Describe the reaction between halogens and metals?
Halogens react with metals to form salts called metal halides
96 of 147
Describe the reaction between halogens and hydrogen?
Halogens can react with hydrogen to form hydrogen halides
97 of 147
Describe hydrogen halides?
Soluble in water, when dissolved in water they form acidic solutions
98 of 147
What's the trend of reactivity with halogens?
Higher up group 7 means more reactive because outer shell closer to nucleus so pull for other electrons is stronger, when halides dissolve in water the halide ions are free to react, more reactive halogen will displace others in halide solution
99 of 147
What are the elements in group 0/8 called?
Noble gases
100 of 147
Describe noble gases at room temperature?
Colourless gases
101 of 147
What do noble gases react with?
Noble gases are inert because they have a full outer shell, they're also non flammable and hard to observe
102 of 147
How were noble gases discovered?
Chemists noticed that nitrogen from the air had a different density to nitrogen taken from chemical reactions therefore other gases must be mixed in, discovered using fractional distillation of air
103 of 147
Uses of argon?
Argon provides an inert atmosphere in filament lamps, prevents filament from burning, protects metals from burning when melding
104 of 147
Uses of helium?
Airships and party balloons, has lower density than air so floats
105 of 147
What's the trend of with noble gases?
Higher densities and boiling points as you move down the group
106 of 147
What must happen to break bonds?
Energy must be supplied
107 of 147
What's the process of bond breaking?
Endothermic reaction
108 of 147
What's the process of bond making?
Exothermic reaction
109 of 147
What's an exothermic reaction?
Gives out energy in the form of heat to the surroundings
110 of 147
Why do exothermic reactions cause a rise in temperature?
The energy released in forming bonds is greater than the energy used in breaking old bonds in the reactants
111 of 147
An example of an exothermic reaction?
Burning fuels, making new bonds of water with carbon dioxide gives out more energy than breaking bonds in the fuel
112 of 147
What's an endothermic reaction?
Takes in heat energy from surroundings
113 of 147
Why do endothermic reactions consume heat?
The energy required to break old bonds in the reactants is greater than the heat energy released by forming new bonds
114 of 147
Which of the 2 reactions is more common?
Exothermic
115 of 147
2 examples of endothermic reactions?
Photosynthesis, ammonium nitrate dissolving in water
116 of 147
Which reaction has happened if the products are at a lower energy than the reactants?
Exothermic
117 of 147
Which reaction has happened if the products are at a higher energy than the reactants?
Encodthermic
118 of 147
Which 4 reaction types would you need to measure the temperature for?
Dissolving salts in water, neutralization (acid+base), displacement, precipitation
119 of 147
How do you measure the energy produced by a chemical reaction?
Take temperature of reactants, mix in polystyrene cup then measure at end of reaction
120 of 147
How do you combat heat loss in temperature measurements?
Put cotton wool around the cup
121 of 147
What's one of the slowest reactions?
The rusting of iron
122 of 147
What 4 things does the rate of reaction depend on?
Temperature, concentration (pressure for gases), catalyst, surface area of a solid (or size of particles)
123 of 147
How do you tell which reaction is quicker on a graph?
The line that goes flat the quickest
124 of 147
Describe the practical to investigate effect of surface area and concentration on reaction rate?
Hydrochloric acid+marble chips, measure gas produced by a gas syringe, repeat with same variables but crush chips more, repeat with powdered chips
125 of 147
Describe the practical to investigate affect of temperature on reaction rate?
Sodium thiosulfate and HCL, react to form yellow sulfur precipitate, look at black paper through solution, reaction ends when mark not visible, repeat at different temperatures
126 of 147
How do catalysts affect rate of reaction?
Catalysts lower the energy required by the reactants to react, makes it easier for reaction to happen and increases reaction rate, allows lower temperature to be used
127 of 147
Use of catalysts?
Catalytic converters in vehicle exhausts, speeds up carbon monoxide into carbon dioxide+water reaction
128 of 147
What's the generic reason that reaction rate increases?
Increased collisions
129 of 147
Why does higher temperature increase reaction rate?
The particles have more energy and move quicker so there are more frequent collisions
130 of 147
Why does higher concentration (or pressure) increase reaction rate?
More particles of reactant leading to more likely collisions, in a gas the particles are squashed more closely so more frequent collisions
131 of 147
Why does larger surface area increase reaction rate?
Particles have a larger area to react with so more frequent collisions
132 of 147
How do catalysts increase reaction rate in terms of collisions?
Gives reacting particles a surface to stick to leading to increased successful collisions by lowering required energy
133 of 147
What do reactions need in order to happen?
Enough energy to collide with
134 of 147
How do you find the relative atomic mass (RAM)?
Look at the mass number (it's the same)
135 of 147
What is relative formula mass (RFM)?
All of the RAM's added together in a compound
136 of 147
How do you work out RFM?
Add all RAM's together, including the quantities of each element (eg cl2 requires RAM x2)
137 of 147
How do you calculate percent mass of an element in a compound?
RAM x number of atoms (of element)/ RFM (of whole compound) x 100
138 of 147
What is the empirical formula?
The exact formula of a compound worked out bu finding ratios of elements to each othet
139 of 147
How do you calculate empirical formula from masses?
List all elements in the compound, write given masses for the experiment, divide mass by RAM (individually), divide answer by lowest answer of all elements
140 of 147
How do you calculate masses in reactions?
Write out the balanced equation, work out RFM (for the 2 bits you want), divide one RFM by itself to get 1 then multiply to work out any mass, do the same to both sides
141 of 147
What is percentage yield?
A comparison of actual and theoretical yield
142 of 147
What's reaction yield?
The mass of a product it produces
143 of 147
How do you calculate percentage yield?
actual yield/theoretical yield then x 100(all units in grams)
144 of 147
How often do you get a 100% yield
Almost never
145 of 147
What are 3 reasons for less than 100% yield?
Incomplete reactions (not all reactants converted to product), practical losses during experiment (eg transferring liquid between containers), unwanted reactions (other reactions using up reactants)
146 of 147
What do chemists look for in reactions for an industry?
High percentage yield so no expensive raw materials are wasted, all products are commercially useful, suitable speed (quickly and safely)
147 of 147
Other cards in this set
Card 2
Front
Describe the electrons in the atom?
Back
They move around the nucleus, have a negative charge, tiny compared to nucleus but move around and cover alot of space, the size of their orbits determines how big the atom is, virtually no mass and occupy shells around the nucleus
Card 3
Front
What's a shell?
Back
Card 4
Front
How does the number of protons compare to the number of electrons?
Back
Card 5
Front
What charge do protons, neutrons and electrons have?
Back
Similar Chemistry resources:
2.0 / 5 based on 1 rating
3.5 / 5 based on 2 ratings
2.0 / 5 based on 1 rating
4.0 / 5 based on 17 ratings
4.0 / 5 based on 13 ratings
0.0 / 5
5.0 / 5 based on 1 rating
4.0 / 5 based on 1 rating
Comments
No comments have yet been made