1. Building Blocks (Year 8) Mike Turner, Jan. 2004 Building Blocks (Year 8) Click to move on

2. Building Blocks (Year 8) Mike Turner, Jan. 2004 Particle and Kinetic Theory Substances are made up of particles. The state of the substance depends on the arrangement of the particles. Solid  Particles held tightly  Very close together  Regular arrangement  Vibrate  Can’t move from place to place Liquid  Particles held weakly  Very close together  Random arrangement  Vibrate  Constantly move past each other Gas  No attraction between particles  Far apart  Random arrangement  Vibrate  Move quickly in all directions The Three States of Matter Click to move on

3. Building Blocks (Year 8) Mike Turner, Jan. 2004 Atoms and Elements Elements consist of only one type of particle. We call these particles atoms. They cannot be split into simpler, smaller particles by chemical methods. There are about 109 elements known at the moment (2004). Don’t worry, you don’t have to learn them all! The elements each have a name and a symbol. By the end of year 9, you must know the first twenty elements off by heart, so it is a good idea to start learning them now! Click to move on

4. Building Blocks (Year 8) Mike Turner, Jan. 2004 The First Twenty Elements Atomic Number SymbolName Atomic Number SymbolName 1Hhydrogen11Nasodium 2Hehelium12Mgmagnesium 3Lilithium13Alaluminium 4Beberyllium14Sisilicon 5Bboron15Pphosphorus 6Ccarbon16Ssulphur 7Nnitrogen17Clchlorine 8Ooxygen18Arargon 9Ffluorine19Kpotassium 10Neneon20Cacalcium Click to move on

5. Building Blocks (Year 8) Mike Turner, Jan. 2004 Arranging the Elements As you know, the elements are arranged in the Periodic Table. Click to move on The elements were first arranged in this way by Dmitri Mendeleev, a professor at St. Petersburg University, in 1869. His arrangement was based on atomic mass. When Mendeleev was setting out the table, only 63 elements had been discovered. His big idea was to leave gaps for yet to be discovered elements. He was able to predict the properties of some of these elements, including silicon and boron. When his predictions were shown to be accurate his table became accepted, and it is the basis of the one we use today. ‘Maybe one day we’ll understand why Dmitri always lays out his blocks this way!’

6. Building Blocks (Year 8) Mike Turner, Jan. 2004 Arranging the Elements : Metals and Non-Metals Most of the elements are metals. The non-metals are found to the top right of the periodic table. The metals and non-metals are separated by a sort of ‘stair case’. Click to move on

7. Building Blocks (Year 8) Mike Turner, Jan. 2004 Arranging the Elements : Groups and Periods The columns of the periodic table are called Groups. Elements in a group have similar properties. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 0 Group 1 : Alkali metalsGroup 2 : Alkaline earth metalsGroup 7 : HalogensGroup 0 : Noble gases Transition metals The horizontal rows are called Periods. Click to move on

8. Building Blocks (Year 8) Mike Turner, Jan. 2004 Properties of Metals Metals have the following properties :  They conduct electrical energy well  They conduct thermal energy well  They are shiny  They are malleable (can be hammered into shape)  They are ductile (can be drawn out into wires)  They are sonorous (make a ringing sound when hit)  All except mercury are solids at room temperature Only a few metals are magnetic. Magnetism is not a property of most metals! Click to move on

9. Building Blocks (Year 8) Mike Turner, Jan. 2004 Properties of Non-Metals Non-metals have the following properties :  They are poor conductors of electrical energy  They are poor conductors of thermal energy  Many of them are gases  They are brittle if they are solid Both a diamond and a pencil ‘lead’ are made of the same element – carbon. Click to move on

10. Building Blocks (Year 8) Mike Turner, Jan. 2004 Elements, Molecules and Compounds Some elements, such as the noble gases, exist as individual atoms. Often, elements consist of two or more atoms joined together. We call these molecules. If more than one type of atom is in a molecule, we call it a compound. Click to move on

11. Building Blocks (Year 8) Mike Turner, Jan. 2004 Mixtures This is a mixture of elements made up of atoms, elements made up of molecules, and compounds. In a mixture, the particles are not joined together. Atom, molecule or compound? (click for answer) Atom, molecule or compound? (click for answer) Atom, molecule or compound? (click for answer) atom molecule compound Click to move on

12. Building Blocks (Year 8) Mike Turner, Jan. 2004 magnesium + oxygen  (click for answer) magnesium + oxygen  magnesium oxide Naming Compounds If we heat copper in air, it reacts with the oxygen to make a new compound. We call this compound copper oxide. We can write a word equation for this : copper + oxygen  copper oxide Most metals will react with oxygen to form an oxide. For example : When metals react with oxygen we often say they are corroding. Iron is a very common metal (steel is mostly made of iron), and it reacts with oxygen to make the compound iron oxide. This is such a common reaction that we give the compound iron oxide a common name – rust! Iron is the only metal that rusts. The correct term to use for other metals is that they corrode. Click to move on

13. Building Blocks (Year 8) Mike Turner, Jan. 2004 More Oxygen Compounds Oxygen also reacts with some non-metals to form compounds. When carbon burns, the following reaction happens : carbon + oxygen  carbon dioxide C + O 2  CO 2 And of course, oxygen reacts with hydrogen to form a very common compound! hydrogen + oxygen  water 2H 2 + O 2  2H 2 O A molecule of carbon dioxide – one atom of carbon and two atoms of oxygen A molecule of water – one atom of oxygen and two atoms of hydrogen Click to move on

14. Building Blocks (Year 8) Mike Turner, Jan. 2004 magnesium + sulphur  (click for answer) magnesium + sulphur  magnesium sulphide More Compounds Naming compounds is quite straightforward when you get used to it. When metals react with chlorine, they form chlorides. sodium + chlorine  sodium chloride lithium + chlorine  (click for answer) lithium + chlorine  lithium chloride With sulphur, sulphides are formed. iron + sulphur  iron sulphide Salt (sodium chloride) crystals are made up of millions of sodium and chlorine atoms. Click to move on

15. Building Blocks (Year 8) Mike Turner, Jan. 2004 Element or Compound? methane, CH 4 (Click for answer) compound sulphur, S 8 (Click for answer) element hydrogen peroxide, H 2 O 2 (Click for answer) compound sulphuric acid, H 2 SO 4 (Click for answer) compound oxygen (ozone), O 3 (Click for answer) element carbon (buckyball), C 60 (Click for answer) element Click to move on

16. Building Blocks (Year 8) Mike Turner, Jan. 2004 Testing for Gases In some chemical reactions, gases are given off. There are several simple tests we can do to find out which element or compound a gas is. Here are two of them. Carbon dioxide Bubble the gas through lime water. If the lime water turns milky, the gas is CO 2. Oxygen Hold a glowing splint in the gas. If the splint relights, the gas is O 2. Click to move on

17. Building Blocks (Year 8) Mike Turner, Jan. 2004 You have now reached the end of the revision presentation for the ‘Building Blocks’ topic. I hope you have found it useful. If you have any ideas to improve this presentation please let Mr. Turner know. Thank you for looking at this work, and good luck in your test. Click to finish