C2 AQA Revision Notes

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…

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.…

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…

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…

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 =…

much product as possible means less waste. 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)…

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…

1. 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…