Compounds and Mixtures 14/05/2018 Compounds and Mixtures

These atoms are ALL iron – there’s nothing else in here Elements 14/05/2018 If a solid, liquid or gas is made up of only one type of atom we say it is an element. For example, consider a tripod made up of iron: These atoms are ALL iron – there’s nothing else in here

Sodium chloride (salt) Compounds 14/05/2018 Compounds are different to elements. They contain different atoms. Here are some examples: Sodium chloride (salt) Methane Glucose

Some simple compounds… 14/05/2018 Methane, CH4 Carbon dioxide, CO2 Water, H2O Key Hydrogen Oxygen Carbon Sulphur Sulphuric acid, H2SO4 Ethyne, C2H2

Water, iron oxide or carbon dioxide? Making compounds 14/05/2018 Compounds are made when two or more elements (or compounds) go through a chemical reaction. For example: When carbon reacts with oxygen it usually forms ____ _________ When oxygen reacts with hydrogen it could form ______ When iron reacts with oxygen it could form ______ ______ There are usually “tell-tale” signs to show when a compound is being made, such as bubbling, heat given off, colour changes, fizzing etc. Water, iron oxide or carbon dioxide?

Rule 1 – When two elements join the end is usually _______ide. Naming compounds 14/05/2018 Rule 1 – When two elements join the end is usually _______ide. e.g. Magnesium + oxygen magnesium oxide Sodium + chlorine Magnesium + fluorine Lithium + iodine Chlorine + copper Oxygen + iron KBr LiCl CaO MgO2 KF

e.g. Copper + sulphur + oxygen Copper sulphate Naming compounds 14/05/2018 Rule 2 – When three or more elements combine and one of them is oxygen the ending is _____ate e.g. Copper + sulphur + oxygen Copper sulphate Calcium + carbon + oxygen Potassium + carbon + oxygen Calcium + sulphur + oxygen Magnesium + chlorine + oxygen Calcium + oxygen + nitrogen AgNO3 H2SO4 K2CO3

Naming compounds 14/05/2018 Rule 3 – If two identical elements combine then the name doesn’t change This happens with the following elements: H2 N2 O2 F2 Cl2 Br2 These elements always go around in pairs. For example, hydrogen looks like this:

Mixtures 14/05/2018 Before After 100 g 105 g

Element, mixture or compound? 14/05/2018 Salty water Hydrogen Hydrochloric acid Air Diamond Sodium chloride (salt)

Air 14/05/2018 Air is a mixture… 1% 21% 18% 0.03% 79% 79%

Fractional distillation Separating air 14/05/2018 Air can be separated into the different gases that make it up. To do this you first have to cool air down to -2000C and turn it into a liquid: Fractional distillation Nitrogen Liquid air Argon Oxygen In this chamber the air is gradually heated up again and the different parts of air “distil” off at different temperatures according to their boiling points