Presentation on theme: "Teacher’s Notes A slide contains teacher’s notes wherever this icon is displayed - To access these notes go to ‘Notes Page View’ (PowerPoint 97) or ‘Normal."— Presentation transcript:
2 Teacher’s NotesA slide contains teacher’s notes wherever this icon is displayed -To access these notes go to ‘Notes Page View’ (PowerPoint 97) or ‘Normal View’ (PowerPoint 2000).Notes Page ViewNormal ViewFlash FilesA flash file has been embedded into the PowerPoint slide wherever this icon is displayed –These files are not editable.
3 Elements and Compounds Elements are materials made up of one type of atom only.Hydrogen molecule contains two hydrogen atoms bonded together, so the formula is H2.It follows that compounds contain two or more types of atom.The water molecule contains two hydrogen atoms bonded to one oxygen atom, so the formula is H2O.
4 Compounds: WaterCompounds are produced when elements combine. For example, water is produced in the following reaction.+Two water molecules react with one oxygen molecule to give water.Word EquationHydrogen Oxygen Water
5 Compounds – not mixtures The atoms in compounds are NOT mixed together. A mixture of hydrogen and oxygen would look like:They become bonded together during a chemical reaction. Because of this compounds have properties that are very different to the elements that they are made from.HYDROGENFlammable gas.OXYGENGas in which many substances burn.WATERLiquid that extinguishes most fires.+
6 Compounds – not mixtures Black solid used as barbecue fuelGas in which many substances burnGas used in fizzy drinks and fire extinguisherscarbon oxygen carbon dioxide
7 Naming Simple compounds. It is easy to name simple compounds of metals and non-metals.Write down the name of the metalWrite down the name of the non-metal but change the ending to “ide.”1) magnesium 2) oxygen =magnesiumoxide1) sodium 2) chlorine =sodiumchlorideoxygencalciumsulphursilverbrominecopperName of compoundElement 2Element 1copper bromidesilver sulphidecalcium oxide
8 Naming Simple compounds. Name the compound formed from these elementsnitrogenlithiumsulphurzinciodinenickelbrominealuminiumoxygentinchlorinesodiummagnesiumironName of compoundElement 2Element 1iron sulphidemagnesium nitridesodium chloridetin oxidealuminium bromidenickel iodidezinc sulphidelithium nitride
9 Naming more complicated Compounds Many compounds contain more than two elements. Naming them can get complicated but for those containing two elements plus oxygen the name ending usually changes to –ate.oxygenbrominealuminiumsulphurcopperElement 3nitrogensodiummagnesium nitratemagnesiumnickel sulphatenickelName of compoundElement 2Element 1sodium nitratecopper sulphatealuminium bromate
10 The composition of compounds. Compounds are very different to the elements from which they are made but there is another way in which compounds are different to mixtures.In a mixture you can add any amount of the ingredients.Compounds always contain a definite amount of each element. They have a fixed composition.This is not really surprising as looking at the word equations you will have seen they always have a definite number of element atoms joined together.NaClOHOCMgO
11 The formula of compounds This means that every compound can have a formula that tells us how many of each type of atom are present. We include small slightly dropped numbers if there are more of one atom than the other.Carbon dioxideOne carbon atomTwo oxygen atomsFormula CO2OCWaterOne oxygen atomTwo hydrogen atomsFormula H2OOH
12 The formula of compounds ActivityThe formula of compoundsWhat is the formulae of each of the compounds shown?(As with names, put the metal first.)1. Titanium oxide? titanium atom? oxygen atomsFormulaTiO1 titanium atomFormulaTiO22 oxygen atoms2. Lithium OxideLiO? oxygen atom? lithium atomsFormula?3. Aluminium chloride? aluminium atom? chlorine atomsFormulaAlCl2 lithium atoms1 aluminium atomFormulaLi2O1 oxygen atomFormula AlCl33 chlorine atoms
13 The formula of compounds ActivityThe formula of compoundsSilicon chloride? silicon atom? chlorine atomsFormulaClWhat is the formulaeof each of the compoundsshown?ClSiCl1 silicon atomCl4 chlorine atomsFormula SiCl4Aluminium oxideManganese oxideOOOOMnOAlAl1 manganese atom? manganese atom2 aluminium atom? aluminium atomFormula Al2O3FormulaFormula MnO2Formula? oxygen atoms2 oxygen atoms3 oxygen atoms? oxygen atoms
14 Word EquationsWord equations can be used to describe any chemical change. (i.e. any process where the atoms become joined (bonded) in different ways).The steps are:Write down the name of the reactant(s) linking them with a + sign if there is more than one.Write down an arrowWrite down the names of the products linking them with a + sign if there is more than one
15 Word Equations Write out word equations for this reaction ActivityWord EquationsWrite out word equations for this reactionLead reacts with oxygen to form lead oxideLead oxygen lead oxideLeadLead oxideIt hasn’t just mixed.It has reacted and atoms are joined differently.Why is lead oxide so different to both lead and oxygen?
16 Word Equations Write out word equations for the following reactions. ActivityWord EquationsWrite out word equations for the following reactions.Limestone (calcium carbonate) is heated to make calcium oxide and carbon dioxide.Magnesium reacts with hydrochloric acid to make magnesium chloride and hydrogen.Methane is burnt to make carbon dioxide and water.calcium carbonate calcium oxide +carbon dioxidemagnesium + hydrochloric acid magnesium chloride + hydrogenmethane + oxygen carbon dioxide + water
17 sea water: a mixture of salts and water MixturesMixtures are, as the name indicates, mixed rather than reacted together.This means that, unlike compounds:1 They do not have to have any particular proportions of the various ingredients.2 Their properties are often “an average” of the properties of their ingredients. (eg. a mixture of a black and white powder is grey!)sea water: a mixture of salts and water3 They are mixed, not bonded, and so are usually not too hard to separate back into their ingredients. (For example, it is easy to get salt from sea water.)
19 Separating Mixtures Immiscible liquids Immiscible means “doesn’t mix” and so we are talking about “mixtures” like water with cooking oil or water with petrol.On a small scale you can simply remove the top layer using a pipette.oilwateroilwater
20 Separating Mixtures Miscible liquids Miscible means “does mix” and so we are talking about mixtures like water and alcohol or petrol with kerosine.These are separated by boiling them as it is unlikely that they will boil at exactly the same temperature.In order to “get back” the liquids we use a condenser. This is a tube that has cold water circulating through the outside. It cools down vapours and condenses them back to a liquid. Substances with low boiling points collect first, while those with higher boiling points collect later.
22 Separations Mixture Wanted Method Glass and water glass Sea water salt How would you get this?MixtureWantedMethodGlass and waterglassSea watersaltwaterCooking oil & watercooking oilAlcohol and wateralcoholfilterevaporatedistilpipettedistil
23 Separation Experiment John has been given a mixture of salt, sand and water. He needs to separate them but cannot remember how.Can you help him?Write an experimental plan for John to follow so that he can have the sand, salt and water in separate containers.Make sure you start off by telling him what equipment he will need.Then he will need a step by step plan that is easy to follow.
25 1. Which of these is a compound? brominecoppercarbon dioxideuranium
26 Which of these best describes a compound? Two or more atoms bonded together.Two or more elements mixed together.Two or elements bonded together.Two or more types of molecule mixed together.
27 Which of these could best describe compounds? Substances that: are similar to the elements that they are made from.can be formed when elements react together.can be formed when elements decompose into two or more new substances.substances with symbols in the Periodic Table.
28 What would be the name of a compound formed from sulphur, oxygen and zinc? sulphur zincidesulphur zincatezinc sulphidezinc sulphate
29 What would be the formula of a compound containing two aluminium atoms for every three sulphur atoms?A. Al2S3 B. Al3S2C. Al2S3 D. Al3S2
30 How would you separate a mixture of water and alcohol How would you separate a mixture of water and alcohol. (Two miscible liquids)filteringchromatographyevaporationdistillation
31 What is the main technique you would use when separating a mixture of salt and sand? filteringchromatographyevaporationdistillation
32 Use the chromatogram to decide which dyes are in the ink. A B C D Ink