25/10/2015 Compounds and Mixtures

25/10/2015Elements 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

25/10/2015Compounds Compounds are different to elements. They contain different atoms. Here are some examples: Glucose Methane Sodium chloride (salt)

25/10/2015 Some simple compounds… Methane, CH 4 Water, H 2 O Carbon dioxide, CO 2 Ethyne, C 2 H 2 Sulphuric acid, H 2 SO 4 Key Hydrogen Oxygen Carbon Sulphur

25/10/2015 Making compounds Compounds are made when two or more elements (or compounds) go through a chemical reaction. For example: 1)When carbon reacts with oxygen it usually forms ____ _________ 2)When oxygen reacts with hydrogen it could form ______ 3)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?

25/10/2015 Naming compounds Rule 1 – When two elements join the end is usually _______ide. e.g. Magnesium + oxygen magnesium oxide 1)Sodium + chlorine 2)Magnesium + fluorine 3)Lithium + iodine 4)Chlorine + copper 5)Oxygen + iron 6)KBr 7)LiCl 8)CaO 9)MgO 2 10)KF

25/10/2015 Naming compounds Rule 2 – When three or more elements combine and one of them is oxygen the ending is _____ate e.g. Copper + sulphur + oxygenCopper sulphate 1)Calcium + carbon + oxygen 2)Potassium + carbon + oxygen 3)Calcium + sulphur + oxygen 4)Magnesium + chlorine + oxygen 5)Calcium + oxygen + nitrogen 6)AgNO 3 7)H 2 SO 4 8)K 2 CO 3

25/10/2015 Naming compounds Rule 3 – If two identical elements combine then the name doesn’t change This happens with the following elements: 1)H 2 2)N 2 3)O 2 4)F 2 5)Cl 2 6)Br 2 These elements always go around in pairs. For example, hydrogen looks like this:

25/10/2015Mixtures 100 g 105 g Before After

25/10/2015 Element, mixture or compound? Salty waterHydrogen Hydrochloric acid Sodium chloride (salt) Diamond Air

25/10/2015Air Air is a mixture… 79% 21%18% 0.03% 1%

25/10/2015 Liquid air Separating air Air can be separated into the different gases that make it up. To do this you first have to cool air down to C and turn it into a liquid: Fractional distillation 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 Oxygen Argon Nitrogen