C2 AQA Revision Notes

I'm sorry if these aren't quite finished but these notes got me 100/100 on my C2 exam last summer

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Structures and Bonding
The Atomic Structure
Contains the same amount of protons and electrons, making the charge 0.
Protons +1
Neutrons 0
Electrons 1
The Arrangement of electrons in atoms
Each shell represents a different energy level. Lowest energy level is shown by the shell which is nearest to the nucleus.
Electrons in the outer shells have more energy than those closer to the nucleus.
First shell can only hold 2 electrons
2nd shell onwards can only hold 8 electrons
Electronic structure of carbon written as 2, 4 2 electrons on the inner shell and 4 on the outer shell
PERIODIC TABLE horizontal rows called periods vertical columns called groups
As we move across a period each element has one more electron in its outer shell than the element before it.
All elements in group 1 have one electron in their outer shell. The noble gases, except helium, have 8 electrons in their
outer shell.
Chemical Bonding
When an atom has a full outer shell, it is stable and unreactive. When atoms react they take part in changes which give
them a stable arrangement of electrons
Sharing electrons covalent bonding
Transferring electrons ionic bonding
By gaining electrons the element turns negative. By releasing electrons the element turns positive.
Ionic Bonding
Strong forces of attraction between oppositely charged ions electrostatic force acts in all directions ionic bond
The ionic bonds can result in the particles arranging in a giant structure
The force exerted by an ion on other ions in the lattice is exerted equally
In some cases one of the atoms needs to gain or lose more electrons than the other has to lose or gain. In this case, two
or more atoms of each element may react. For example, think about calcium chloride. Each calcium atom needs to lose
two electrons but each chlorine atom needs to gain only one electron. This means that two chlorine atoms react with every
one calcium atom to for calcium chloride. So the formula of calcium chloride is CaCl2

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Covalent Bonding
When nonmetals react together, they share electrons and form molecules
The atoms of nonmetal generally need to gain electrons to achieve a stable outer shell. When they react together neither
atom can give away electrons, so they get the electronic structure of a noble gas by sharing electrons.…read more

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Higher ­ Covalent bonds are very strong. So the atoms within a molecule are held tightly together, even though they are
quite separate from its neighbouring molecules. There is a small amount of attraction between the individual
molecules in a covalent compound overcoming these forces does not take very much energy ­ weak
intermolecular forces
Although a substance that is made up of simple molecules may be a liquid at room temperature, it will not conduct
electricity.…read more

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Moles ­ Writing Ar and Mr may seem clumsy ­ shorthand = moles. 1 mole = Ar/Mr in grams. A mole of any substance
always contains the same number of particles.
Percentages and Formulae
To calculate the percentage of an element in a compound:
Write down the formula of the compound.
Using the relative atomic masses from your data sheet work out the relative formula mass of the compound.
Write down the mass of each element making up the compound as you work it out.…read more

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Our balanced equation tells us that 2 moles of hydrogen react with one mole of oxygen to give 2 moles of water. So turning
this into masses we get:
2 moles of hydrogen = 2x2g = 4g
1 mole of oxygen = 1x32g = 32g
2 moles of water = 2x18g = 36g
The following formula can be used to find out how much of two chemicals are used to react together. Sodium
hydroxide reacts with chlorine gas to make bleach.…read more

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It means that making as much product as possible is made ­ good news
for company's finances + environment
We can calculate percentage atom economy using this equation:
Percentage atom economy = x100
Example ­ Ethanol (C2H5OH) can be converted into ethene (C2H4) which can be used to make polyethene
C2H5OH C2H4 + H2O
(12x2)+ (1x4) (1x2) + (16x1)
=28 =18
Percentage atom economy = x100 = 61%
Reversible Reactions
= equilibrium sign ­ products can react together to produce the original reactants again ­…read more

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The reaction in the Haber process is reversible. The Haber process is carried out in conditions that have been carefully
chosen to give a reasonable yield of ammonia as quickly as possible.
How Fast?
Rate of reaction is very important in the chemical industry. Any industrial process has to make money by producing useful
products ­ make as much of the product as possible as cheaply as possible.…read more

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Particles collide more often
When we heat up a substance, energy is transferred to the particles that make up the substance. This
means that they move faster. And when particles move faster they have more collisions.
2. Particles collide with more energy
Particles that are moving quickly have more energy, which means that the collisions they have are more
energetic. When we increase the temperature of a reaction, the particles have more collisions and they have
more energy. This speeds up the reaction.…read more


Khadija Siddiqui

thank you this really helped me!

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