D. Crowley, 2007

 To understand the term element and compound

 In small groups, look at the list of substances - how can we group these?  Copper; Carbon Dioxide; Oxygen; Chlorine; Air; Water; Magnesium; Hydrogen; Iron Oxide (Rust); Calcium Chloride; Calcium; Magnesium Oxide; Copper Carbonate; Nitrogen; Iron and Carbon

 The best way to group that list would have been to split them into elements and compounds  There are approximately 100 elements - these are used to make every other substance we know…

 What do you know by the term atom?  Everything is made from atoms - tiny particles  We draw atoms like small circles We usually imagine atoms as being like tiny ball And we draw atoms like small circles

 There are over 150 types of atom…  A substance which contains just one type of atom is known as an element  As there are over 150 types of atom, there are types types of element

 There are over 150 types of atom…  A substance which contains just one type of atom is known as an element  As there are over 150 types of atom, there are 150 types types of element

 An element is made up of one type of atom  An atom is the smallest part of an element you can get  Note - elements consist of just one type of atom (but there are countless numbers of atoms, not just one)!  + they all have their own symbol

 E.g. lead and gold are different elements  Lead contains only lead atoms  Gold contains only gold atoms  You cannot change one element into another element, or anything simpler, using chemical reactions  This is why you cannot turn lead into gold!

 There are only around 150 elements (150 types of atom), but there are millions of different substances - why is this?  The atoms of different elements can join together in chemical reactions, forming compounds

 E.g. oxygen and hydrogen are elements  They react together forming water  Water is therefore a compound - it is made up of oxygen atoms and hydrogen atoms which have joined together by a chemical reaction

 The properties of compounds are usually very different from the properties of the elements they contain  E.g. the elements hydrogen and oxygen are both gases at room temperature, but the compound they form (water) is a liquid at room temperature

 E.g. iron and sulphur are both elements (made of one type of atom)  If you heat them, you can make the compound iron sulphide (they undergo a chemical reaction) + Carbon Oxygen Carbon Dioxide + + CC O O O Another example is in the production of carbon dioxide, from carbon and oxygen elements O

 Look at the table below - copy it out and tick if you think the substance is a single element, or more than one element SubstanceMolecule Formula Single element? More than one element? OxygenO2O2 Carbon monoxideCO HeliumHe WaterH2OH2O Sodium chlorideNaCl Carbon dioxideCO 2 YES NO YES NO

See if you can draw out a particle theory box for copper (solid) aluminium (solid) mercury (liquid) oxygen (gas)

Copper Element

Aluminium Element

Copper ElementMercury Element Aluminium Element

Copper ElementMercury Element Aluminium ElementOxygen Element

What would the particle boxes look like for water (liquid with 2 hydrogen atoms for every 1 oxygen atom) carbon dioxide (2 oxygen atoms for every 1 carbon atom) iron sulphide (solid with and equal number of iron and sulphur atoms)

Water (H 2 O)

Carbon dioxide (CO 2 )

Water (H 2 O) Carbon dioxide (CO 2 ) Iron sulphide (FeS)