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Fundamentals – Topic 1
The structure of an atomLO: understand the structure of atoms
In each atom, the number of protons will ALWAYS be the same as the number of electrons. This makes sure that the overall charge is zero.
Particle Charge
Proton +1
Neutron 0
Electron -1
Atomic and Mass numberLO: understand how to interpret the periodic table
The Atomic number is ALWAYS the smaller number next to the element. The mass number is always the bigger number.
Example Calculate the following quantities for the element below(i) Atomic number(ii) Mass number(iii) Number of protons(iv) Number of electrons(v) Number of neutrons
LO: understand how to interpret the periodic table
Electron shells
Consider Calcium. Calcium has an atomic number of 20.
How many electronsdoes it have?
All of calcium’s 20 electrons can NOT fit in one orbit. Therefore, there must be
multiple orbits for electrons to occupy
LO: understand how to interpret the periodic table
Shell break down
Atoms have 4 shells where electrons can live
Shell 1 – 2 electronsShell 2 – 8 electronsShell 3 – 8 electronsShell 4 – Whatever is left!
LO: understand how to interpret the periodic table
Example 1
Draw the electron arrangement for sodium
LO: understand how to interpret the periodic table
Example 2
Draw the electron arrangement for oxygen
LO: understand how to interpret the periodic table
Reacting with oxygenWhen something reacts with oxygen, it always form an oxide. e.g.• Magnesium Magnesium oxide• Sodium Sodium oxide• Calcium Calcium oxide• Potassium Potassium oxide
LO: understand why chemical reactions occur
Why do chemical reactions happen?
When elements react together, they do so for a reason. They are trying to achieve a FULL OUTER ELECTRON
SHELL.
Consider the following reaction:
LO: understand why chemical reactions occur
The Noble Gases
LO: understand why chemical reactions occur
The group 8 elements are also known as ‘Noble Gases’. These elements are very unreactive. Why do you think this is?
They are unreactive as they already have a full outer shell. Therefore, they don’t need to try to gain/lose any electrons through reacting to get a full outer shell.
Limestone – Topic 2
What is limestone?
Limestone is a sedimentary rock that is formed over millions of
years from the remains of dead sea creatures.
The chemical name for limestone is CALCIUM
CARBONATE and its formula is CaCO3.
LO: understand the uses and reactions of limestone
Quarrying
To get limestone, it must be dug out of the ground through a process called quarrying.
The limestone can be buried deep underground and the stone covering it must be removed using explosives.
LO: understand the uses and reactions of limestone
The Limestone cycle
The limestone cycle is a set of reactions that allow us to start at limestone and end up back with limestone. For your GCSE course, you need to know details of the three reactions, the word and symbol equations and how to balance them.
LO: understand the reactions of limestone
Thermal decomposition
Calcium carbonate Calcium oxide + Carbon dioxide
LO: understand the reactions of limestone
Calcium Hydroxide
Calcium oxide + Water Calcium Hydroxide
LO: understand the reactions of limestone
Limewater
Limewater can be made from calcium hydroxide solution by diluting it with additional water.
LO: understand the reactions of limestone
Limewater
Limewater is commonly used to test for carbon dioxide. When there is carbon dioxide present, the limewater goes from being clear to milky/cloudy
LO: understand the reactions of limestone
Calcium Hydroxide
Calcium Hydroxide + Carbon dioxide Calcium Carbonate
LO: understand the reactions of limestone
Check:LO: understand the reactions of limestone
CaCO3
CaO
Ca(OH)2
Limewater Ca(OH)2
