The structure of an atom LO: 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. ParticleCharge Proton+1 Neutron0 Electron

Atomic and Mass number LO: 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. 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 electrons Shell 2 – 8 electrons Shell 3 – 8 electrons Shell 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 oxygen When 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.

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 CaCO 3. 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 CaCO 3 CaO Ca(OH) 2 Limewater Ca(OH) 2