C4, C5, C6 OCR Complete GCSE Revision Notes

Everything you need to know for C4, C5 and C6 for the exam on 28th June.

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  • Created on: 06-06-11 22:37
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Chemistry Revision ­ C4, C5, C6
C4 ­ Chemical Patterns
The nucleus is made of protons (positive) and neutron (negative).
o It makes up the whole mass displayed on the periodic table.
o But size wise it's a small part of the atom.
The electrons move around the nucleus.
o They are negative.
o Arranged in shells.
o Virtually no mass.
o The shells explain the whole of chemistry.
Number of protons always equals the number of electrons.
o So atoms normally have no overall charge.
o Neutrons aren't fixed, but normally similar to the number of protons.
Each element has a different number of protons.
o Elements have different properties because of difference atomic structures.
Balancing Equations:
Atoms aren't lost or made in chemical reactions.
You have to make sure you have the same number of atoms on both sides of the arrow.
State symbols
o (s) ­ Solid
o (l) ­ Liquid
o (g) ­ Gas
o (aq) ­ Dissolved in water
Line Spectrums:
Some elements emit distinctive colours when heated.
o Lithium (Li) produces a red flame.
o Sodium (Na) produces a yellow/orange flame
o Potassium (K) produces a lilac flame.
Each element gives a characteristic line spectrum.
o So spectrums can be used to identify elements.
o New elements like caesium and rubidium have been discovered because of their line
The Periodic Table:
The periodic table puts elements with similar properties together.
o It's in increasing proton order.
o Metals found to the left, non metals to the right.
o Elements with similar properties are in columns.
o Groups go across the top, ignore the transition metals.
o So group 1 (Li, Na, K, Rb, Cs, Fr) react in a similar way. The reactivity increases as you
go down the group.

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But in group 7 it decreases as you go down the group.
o Each new period (row) represents another full shell of electrons.
Electron Shells:
Electron shell rules:
o Electrons occupy shells (sometimes called energy levels).
o Lowest energy levels fill first.
o 1st shell: 2 2nd shell: 8 3rd shell: 8
o Atoms like having a full outer shell. It makes them unreactive.
o Electron arrangement determines chemical properties.
Electrons fill up as you go across the periodic table.…read more

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Chlorine merks bacteria, like other halogens, so it's used in swimming pools.
o As you go down the halogens, they get less reactive, higher melting point and higher
boiling point.
Non-metals with coloured vapours.
o Fluorine is a very reactive, poisonous yellow gas at room temperature.
o Chlorine is a fairly reactive, poisonous dense green gas at room temperature.
o Bromine is a dense red-brown volatile liquid at room temp and forms a red brown
gas.…read more

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o Highly flammable
o Toxic
o Harmful
o Irritant
o Corrosive
Alkali metals are really reactive and combust spontaneously.
o If they meet water vapour the can react ;/
o Never touch with bare hands.
o If you use them, keep everything dry.
Halogen are harmful, chlorine and iodine are very toxic.
o Fluorine is the most reactive halogen; it's too dangerous for use in the lab.
o Liquid bromine is corrosive, so don't touch with skin.…read more

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Covalent Bonding:
Covalent bonds share electrons.
o This way both atoms feel they have a full outer shell.
o The atoms bond due to electrostatic attraction between the positive nuclei and the
negative electrons shared between them.
Hydrogen, H
o Hydrogen need 1 more electron, so 2 H's share their outer electron and they have a
full outer shell.
Carbon Dioxide, CO
o Carbon needs 4 more, oxygen needs 2.
o So two double covalent bonds are formed.…read more

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Metals from Minerals:
Ores contain enough metal to make extraction worthwhile.
o Rocks are made or minerals, which are solid elements and compounds.
o Metal ores are rocks that contain various amounts of minerals from which metals can
be extracted.
More reactive elements are hard to get.
o Most elements are in compound form, so they need to be extracted from their ores
in a chemical reaction.
o More reactive metals, like sodium are harder to extract, so they took longer to
discover.…read more

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Ores are finite resources.
o They'll run out.
o Good because useful production, money, jobs so transport and health services can
be improved.
o But it uses loads on energy, scars in landscape, destroys habitats also noise, dust and
pollution are caused by the traffic increase.
o Deep mines can be dangerous for a long time after it's been abandoned.
Recycling is important.
o Mining and extracting takes energy.
o Recycling uses a small proportion of the energy used to extract a new material.…read more

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An acid is a substance with pH below 7, acidic compounds from aqueous hydrogen
ions H.
o An alkali has a pH more than 7 and it makes aqueous hydroxide ions OH in water.
o When they react they make salt and water. The products are neutral, so its
o Acid + Alkali Salt + Water
Acids Reacting with Metals:
Acid + Metal Salt + Hydrogen.
o More reactive metals react faster.
o Copper doesn't react at all because it's less reactive that hydrogen.…read more

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Correct size and strength of apparatus and temperature of reaction and
whether you need to use a catalyst.
o Isolating the product:
After the reaction you might need to separate a mixture, evaporation,
filtration, drying ect.
o Purification:
As you isolate the product you're helping to purify it, crystallisation can help
with the process.
o Measuring yield and purity:
Overall success of process. It compares what you should get, with what you
get in practise.
Purity needs to be measured.…read more

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Titrations are carried out using a burette.
o A know volume of alkali in a flask with a few drops of indicator.
o Then add acid drop by drop until it changes colour.
o It's then neutralised.
Solids are weighed out into a titration flask.
o The add a solvent to make a liquid, but the amount depends on the solvent and the
amount of it.
Some products need to be very pure.…read more


Salsabiil Therese

This is not the new syllabus

Sasha Dean

This is brilliant.

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