1. C2 Topic 1 and 2

2. C2.1 Mendeleev He arranged them by the following properties:
Mendeleev created the periodic table in 1871.
He arranged elements in order of their properties.
-groups = down.
-period= across
Metals are on the left hand side of the periodic table.
He arranged them by the following properties:
Atomic mass
Density
Melting Point
Formula of the oxide
Patterns emerged down the groups and across the periods which confirmed his predictions.

3. The group number corresponds to the number of electrons in the outer shell.
C2.2 Structure of the atom
Electron shells
Atoms are made up of PROTONS, NEUTRONS and ELECTRONS.
They are found in the positions shown on the diagram.
Atom is the smallest of particles.
Particle
Relative Mass
Relative Charge
Proton 1 +1
Neutron
Electron
1/1840 -1
Electrons fill shells from the middle in the order of
2, 8, 8, 18 (how many elements are in each period)
Nucleus containing protons and neutrons

4. C2.3 The Modern Periodic Table
Top number – MASS NUMBER
The number of protons and neutrons
Bottom number – ATOMIC NUMBER
The number of protons
(also the same as electrons)
Isotope -
Elements with the same number of protons and electrons but different number of neutrons. Al 27 13
Protons = 13
Electrons = 13
Neutrons = = 14
Protons and neutrons are packed together tightly in the nucleus (high density)
Electrons are spread out in shells (low density)

5. C2.4 Electron shells Electron located in the shell.
Electronic configuration = how the electrons are arranged in an atom.

6. + C2.5 Ionic Bonding Ionic bonds form between METALS and NON-METALS.
Ionic bonding involves the transfer of ELECTRONS.
Metallic Ions are POSITIVELY charged (CATIONs).
Non-metallic elements are NEGATIVELY charged (ANIONS). +
Loose electron

7. Common Ions Charged Particles.
To become positively charged an atom must lose electrons. To become negatively charged and atom must gain electrons.
Common Ions Charged Particles.

8. C2.5 Ionic compounds- non metal and a metal.
Conduct electricity when MOLTEN (melted) and in an AQUEOUS SOLUTION (dissolved in water)
DO NOT conduct electricity as a SOLID
Have high MELTING and BOILING points
Usually SOLID at ROOM TEMPERATURE
Ion = an atom with a positive or negative charge.
Cations = metal atoms lose electrons to form positively charged ions called cations.
Anions = Non-metal atoms gain electrons to form negatively ions called anions.
Transferring electrons = ionic bonds.
Ionic compounds have a lattice structure, with a regular arrangement of ions, held together by electrostatic forces between oppositely charged ions.

9. C2.6 Ionic compounds
Compound ions = contain more than one element.
Names of ionic compounds =
If the compound contains oxygen it ends with an –ate…..eg….. Iron sulfate = Fe SO4
If no oxygen then they end in an –ide…….Iron Sulfide….FeS
Ionic compounds contain ions. Below are some of the common ones.

10. C2.7 Properties of ionic Compounds
Solid = does not conduct electricity
Liquid = conduct electricity…WHY….ions are free to move around and they are charged.
Melting points = when a substance changes from solid to liquid.
Boiling point = changes from a liquid to a gas.
Ionic substances = high boiling points and high melting points.
Ionic bonds = strong and lots of them to break so needs lots of energy.

11. C2.8 Solubility Soluble = substance dissolves.
Insoluble = does not dissolve
Salt = Acid + alkali
Table explains which salts are soluble and which are not.

12. AgNO3 (aq) + NaCl (aq)→ AgCl (s) + NaNO3 (aq)
2.10 Precipitations.
silver nitrate (soluble) + sodium chloride (soluble)   →   silver chloride (insoluble) + sodium nitrate (soluble)
AgNO3 (aq) + NaCl (aq)→   AgCl (s) + NaNO3 (aq)
Precipitation reaction - An insoluble solid formed when two soluble substances are mixed.
Barium sulfate is used as a ‘barium meal’ to x-ray patients because it is
Opaque to x-rays
Safe to use
Insoluble so doesn’t enter the blood

13. C2.10 Precipitates
Precipitates are SALTS that are formed in chemical reactions that DO NOT DISSOLVE in the solvent used in the reaction.

14. C2.11 Ion Tests
Ion tests for metals (ANIONS) are usually done by FLAME TESTS.
Each ION produces a certain flame colour.
Testing for CATIONS is done through chemical testing.
Chloride – add nitric acid and silver nitrate, if a white precipitate forms then chloride ions are present.
Sulphate – add hydrochloric acid and barium chloride, if a white precipitate forms then sulphate ions are present.
Carbonate – add an acid and if the gas produced turns limewater MILKY the carbonate ions were present.
(carbonate release carbon dioxide)

15. C2 Topic 3 & 4

16. C2.12 Covalent Compounds
Covalent bond is when a pair of electrons are shared between two atoms forming a molecule.
Learn these covalent molecules. Be able to draw them using dot and cross diagrams.
Water H2O
Hydrogen Chloride HCl
Oxygen O2
Methane CH4
Carbon Dioxide CO2
Hydrogen H2

17. C2.13 Properties of Covalent Substances
Simple Covalent Substances
Giant Covalent Substances
Low melting point
Low boiling point
Poor conductor of electricity
Why?
Because there are weak forces between molecules.
High melting point
High boiling point
Why?
Because there are strong forces between molecules.

18. 2.13 Diamond vs. Graphite Diamond Graphite Used to make cutting tools.
Both examples of giant covalent molecules. Both made from CARBON.
2.13 Diamond vs. Graphite
Diamond
Graphite
Used to make cutting tools.
Very hard with strong bonds between molecules.
Does not conduct electricity because there are no free electrons.
Used to make electrodes and lubricant.
There are strong forces between molecules within the layers – but there are weak forces between the layers.
There is one free electron for each carbon atom meaning it can conduct electricity.

19. C2.15 Miscible or Immiscible?
Key definitions Miscible – Liquids that completely mix to form a solution. Immiscible – Liquids that do not form a solution but separate into two layers e.g. oil and water.
Separating two immiscible liquids
Use a separating funnel.
Open the tap and let the lower liquid flow out and collect in a beaker.
Close the tap before the upper liquid starts to run out.
Change the beaker and then let the other liquid flow out.
Separating two miscible liquids
Use fractional distillation to separate liquid air to form nitrogen and oxygen.
Exploits the fact they have different boiling points.
Cool air to -200oC to liquefy it.
Warm up to -185oC to evaporate the nitrogen and keep the oxygen liquid.

20. Rf = distance moved by the compound ÷ distance moved by the solvent
C2.16 Chromatography
Used to separate mixtures of coloured compounds including inks, dyes and colouring agents in food.
A spot of the mixture is placed near the bottom of a piece of chromatography paper and the paper is then placed upright in a suitable solvent, e.g. water.
As the solvent soaks up the paper, it carries the mixtures with it.
Different components of the mixture will move at different rates.
This separates the mixture out.
Rf values
Different chromatograms and the separated components of the mixtures can be identified by calculating the Rf value using the equation:
The Rf value of a particular compound is always the same - if the chromatography has been carried out in the same way. This allows industry to use chromatography to identify compounds in mixtures.
Rf = distance moved by the compound ÷ distance moved by the solvent

21. C2.17 Chemical Classification
Type of bonding
Melting Point
Boiling Point
Solubility in Water
Conductivity
Ionic
High
Most Dissolve
Conduct electricity when molten or in solution, not when solid
Simple molecular covalent
low
Some dissolve in water
Do not conduct electricity
Giant molecular covalent
Insoluble
Do not conduct except graphite
Metallic
High except mercury
Good conductors

22. C2.14 Classifying Substances
Could you classify these substances based on their properties?
Know these examples!
Substance
Melting Point
Boiling Point
Electrical Conductivity
Solubility in water
Type of Bonding
Sodium Chloride
High
Yes in solution or molten
Soluble
IONIC
Magnesium Sulfate
Hexane
Low No
Insoluble
SIMPLE COVALENT
Paraffin
Silicon dioxide
GIANT COVALENT
Copper sulphate
Sucrose

23. C2.18 Metallic Bonding and Transition Metals
The structure of metals – a regular arrangement of positive ions surrounded by a sea of delocalised electrons.
Metals are malleable because ions can slide over each other if a large enough force is applied. The electrons hold the ions together meaning the metal spreads out rather than breaks.
Metals conduct electricity because the delocalised electrons are free to move. If a voltage is applied, the electrons all move in the same direction and this is called a current.
Most metals are transition metals and they typically have high melting points and produce coloured compounds.

24. C2.19 Alkali Metals
Alkali metals are soft with relatively low melting points. Lithium, Sodium and Potassium react with water to form hydroxides (which are alkaline) and hydrogen gas.
Lithium + water  Lithium Hydroxide + Hydrogen
Sodium + water  Sodium Hydroxide + Hydrogen
Potassium + water  Potassium Hydroxide + Hydrogen
Alkali metals get more reactive as you move down the groups because the atoms lower down have more electron shells. This means the outer electron is further away from the nucleus, not held in place as strongly, and easier to lose – making it more reactive.

25. C2.20 Halogens Halogen Colour State at room temperature Fluorine
Pale Yellow
Gas
Chlorine
Green/yellow
Bromine
Brown
Liquid
Iodine
Grey
Solid
Metal + Halogen  Metal Halide
Potassium + Bromine  Potassium Bromide
2K(s) + Br2(l)  2KBr2(S)
Calcium + Chlorine  Calcium Chloride
2Ca(s) + Cl2(l)  2KCl2(S)
They all follow the same pattern. Learn them.

26. C2.21 Displacement of the halogens
Displacement reactions – a more reactive element will displace (take the place of) a less reactive element.
Chlorine is more reactive than bromine so will displace the bromine.
Potassium Bromide + Chlorine  Potassium Chloride
Potassium Chloride + Bromine  No reaction
Chlorine is more reactive than iodine so will displace the iodine.
Sodium Iodide + Chlorine  Potassium Chloride
Sodium Chloride + Iodine  No reaction

27. C2.22 More halogen reactions
Halogens react with hydrogen to make hydrogen halides which will dissolve in water to make acidic solutions.
Hydrogen + Fluorine  Hydrogen Fluoride
H2(g) + F2(g)  2HF(g)
Hydrogen + Chlorine  Hydrogen Chloride
H2(g) + Cl2(g)  2HCl(g)
Salt
Sodium fluoride
Sodium chloride
Sodium bromide
Sodium iodide
Halogen
Fluorine
Reaction
Chlorine
No reaction
Bromine
Iodine
Displacement reactions can be used to work out the relative reactivity of halogens.

28. C2.23 Noble gases
Noble gases are chemically inert (unreactive) because they have a full outer shell of electrons.
Uses of Noble Gases
Reason
Xenon and Argon inside filament lamps
To stop the hot filament reacting with oxygen and burning away
Argon and Helium used in welding
To form a blanket over the hot metal to stop it reacting with oxygen in the air
Argon used in fire extinguishing systems
It is non flammable and can be used to fill a computer server room (for example) if a fire breaks out.
Helium used to fill balloons and air ships
It has low density
Neon in fluorescent lamps
Produces a red light when electric current is passed through it under low pressure
Discovery of Noble Gases
Chemists noticed the density of nitrogen made in a reaction was different from that of nitrogen in the air.
Chemists made a hypothesis about the composition of the air.
Chemists performed tests to show the presence of the Noble gases in the air.

29. Topic 5 Chemical Reactions

30. C2.24 and C2.25 Temperature changes
Facts:
During a chemical reaction there is usually a transfer of energy between the reactant and the surroundings.
C2.24 and C2.25 Temperature changes
Keywords
Endothermic – reaction that takes heat energy in, decreasing the temperature of the reaction mixture and its surroundings
Exothermic – reaction that releases heat energy, increasing the temperature of the reaction mixture and its surroundings
Endothermic
Not many reactions are endothermic
E.g.
Sodium hydrogen carbonate + Hydrochloric acid Sodium Chloride + Water + Carbon dioxide
Other endothermic reactions include:
Photosynthesis
Dissolving ammonium nitrate
Takes in heat energy
Making/breaking bonds
Energy needed to break bond
Energy released when bonds made
Exothermic
Gives out heat
Most reactions are exothermic
Temperature increase
All combustion reactions are exothermic
E.g. Methane + Oxygen
Explosions – release a lot of heat and gases very quickly

31. C2.26, 2.27 and 2.28 Rates of Reactions and Collision Theory
Keywords
Rate of reaction – The speed at which a reaction takes place
Concentration – A measure of how much solute is dissolved in a fixed volume of solvent.
Surface area– The total area of all the surfaces of an object or substance
Examples
Fast reactions = Burning, explosions
Slow reaction = Rusting, apple browning
2. Temperature
Higher temperature = faster reaction
e.g. And egg cooks faster in boiling water than warm water
Particles have more energy = move faster
More effective collisions (collide with more energy)
Collide more frequently
Factors affecting Rate
Concentration
More concentrated = more particles
More particles = more collisions = faster reaction
3. Surface area (SA)
Solid broken up into smaller pieces = larger SA
Greater surface area = faster reaction
More surface area = more particles on the surface therefore more frequent collisions
A = Smaller SA (block)
B = Larger SA (powder)

32. C2.29 Catalysts
Keywords
Catalyst – A substance that speeds up the rate of a reaction without being used up in the reaction
Catalytic converter – Device fitted to car exhausts with a thin layer of transition metal catalyst on a honeycomb structure giving a large surface area.. The catalyst speeds up the reaction to combine Carbon monoxide and unburned petrol into carbon dioxide and water.
Catalysts
Many chemical processes use catalysts to increase rate of production of products
Catalysts help to lower the temperature and pressure needed = less energy needed = saves money
Catalytic converters
Reduce pollutants in exhaust gases
Combine Carbon monoxide (CO) with oxygen
Carbon dioxide and water released instead
Contain transition metals (platinum, rhodium or palladium)
Expensive metals so small amounts used
Catalyst spread over a honeycomb structure = large Surface Area
Works faster with the hot gases from the engine heat it up

33. Topic 6 Quantitative ChemistryB2
Topic 6 Quantitative Chemistry

34. C2.30 and 2.31 Relative Mass Keywords
RAM
Compares mass to that of carbon 12
E.g. Hydrogen is 12X lighter that carbon
RFM
Sum of all masses in the formula
E.g. EF
Simplest whole number ratio of atoms/ions
E.g. H2O there are double the number of hydrogens to oxygen
Keywords
Relative Atomic mass (RAM) – The mean mass of an atom relative to the mass of an atom of carbon-12, which has a mass of 12.
Empirical formula (EF) – The simplest whole number ration of atoms of each element in a compound
Molecular formula (MF) - The actual of atoms of each element that combine to make a molecule of a compound.
Relative formula mass (RFM)– The sum of the relative atomic masses of all the atoms in a formula

35. B2.32 Percentage composition
Percentage by mass of an element in a compound
Number of atoms of element A M = X X
100
No atoms are lost or made in a chemical reaction.
They are rearranged into new substances
You can use relative mass and balanced equations to calculate the mass of a reactant or product.

36. C2.33 Yields
Keywords
Yield – the amount of useful product obtained from a reaction.
Products need to be make as cheaply as possible. Chemists need to make sure the reaction creates as much product as possible.
Theoretical Yield
Maximum calculated amount of a product that could be formed from a given amount of reactants.
Can be calculated from the balanced equation
Assumes all reactant are turned into products and all products harvested
Actual Yield
The actual amount of product obtained from a chemical reaction.
Percentage Yield
The actual yield divided by the theoretical yield as a percentage
Yield usually less than expected – 3 reasons:
Reaction may be incomplete
Some product is lost
Other unwanted reactions may occur making a different product.

37. C2.34 Waste and Profit Cost Effective Process
Keywords
By-products – Any product formed in a reaction in addition to the required product
Waste products – By-products that have no uses
C2.34 Waste and Profit
Disposal of Waste Products
Industry make many useful substances (cement, pesticides, plastics)
Many of the reactions make waste products:
Not useful
Must be disposed of following strict laws
Expensive to dispose
Can cause environmental problems
Can cause social problems (house prices drop or unpleasant smells)
Cost Effective Process
All factories must consider environmental impacts including disposal of waste.
Companies want the most profit
Reactions need to be
High in percentage yield
All products are useful so there are no waste products (or uses found for waste products – econimically viable)
Reactions are fast (quick to make lots of product)