1. Year 9 Chemistry

2. Objectives You should be able to: 1)State that there are more than 100 different elements, each with its own symbol and properties and be to recall the names of the following elements: non-metals: H, O, N, C, S, Cl; metals: Na, Mg, Al, Fe, Pb, Zn, K, Ca and Cu. 2) Research aspects of the history of the atom and the periodic table. 3) State that everything is made up of atoms, or matter when considering the 3 states, solid, liquid and gas. 4) Use electronic balances and measuring cylinders to measure mass (g) and volume (L). Use mass and volume to calculate density. 5) Explain the 3 states of matter in terms of particle spacing, attraction between particles and of their movement (particle theory). Define the physical changes of these states in the terms of melting, evaporating, condensing, freezing (solidifying) and sublimation. * Use the particle theory of matter to explain special properties of matter. e.g., expansion, diffusion.

3. 6) Understand that substances are pure or mixtures. 7) Use the terms element, compound, atom, molecule. Recall some common molecules/compounds and represent them using symbols and/or diagrams. 8) Explain that a formula shows which atoms are present and how many of each. 9) Use the term mixture and illustrate with everyday examples. 10) Use the terms solute, solvent, solution, diluted, concentrated, soluble, insoluble. * insolubility/precipitation 11) Separate mixtures using decant, filter and evaporate and use these techniques. * chromatography, distillation, centrifuging

4. ATOMS What are atoms and how did scientists work out what they are like?

5. A little bit of history 2500 years ago the Greek philosophers like Aristotle thought all matter was one of the 4 elements Earth, Fire, Water and Air. However Democritus was the first one to have the idea that matter was made of small particles. He said that if gold was cut into smaller and smaller pieces eventually we would get to the smallest piece that we couldn’t cut. He called this the atom- meaning non (a) cut (tom). His ideas about the atom were forgotten about for about 2000 years

6. And then John Dalton in 1806 described atoms as small particles that couldn’t be made any smaller and that they make up elements. His drawings of atoms were like balls used on a pool table.

7. Later About 90 years later J.J.Thomson said that atoms had positive and negative charges all mixed around like a ‘plum pudding’.

8. But then…. NZ’s own Ernest Rutherford worked out that the atom had a small, dense central nucleus made of positive protons and neutral neutrons surrounded by an area of mostly empty space which had tiny negatively charged electrons whizzing around.

9. INSIDE THE ATOM! nucleus Electrons = negatively charged particles - very small compared to the others - orbit around the nucleus in rings Protons = positively charged particles Neutrons = neutral (uncharged) particles

10. How to draw an atom

11. Elements Elements always contain only one kind of atom Elements are written on the periodic table There are over 105 elements on the periodic table Each element has a name and can be represented by a symbol

12. Elements Chemical symbols begin with a capital letter and can also have one small (lower case) letter Eg sulfur has symbol S copper has symbol Cu. What would the symbol be for hydrogen, lithium and carbon? Mg

14. Metals Na = sodium Mg = magnesium Al = aluminium Fe = iron Pb =lead Zn = zinc K = potassium Ca = calcium Cu = copper Non-metals H = hydrogen O = oxygen N = nitrogen C = carbon S = sulfur Cl = chlorine Elements you need to know

15. Elements can be either Metals Or Non-metals

16. Metals and Non-metals

17. Physical Properties Metals Are solids (except mercury – a liquid) Are dense (atoms are closely packed) Are often silvery in colour and shiny Are bendy (malleable) Conduct electricity Non-metals Are solids, liquids or gases. Are less dense. Different colours and often dull. Are often brittle. Do not conduct electricity

18. So what do we know about elements Are made of a single kind of atom Eg carbon is made up of carbon atoms( and only carbon atoms) sulfur is made up of sulfur atoms (and only sulfur atoms)

19. These atoms may be separate atoms as in copper (Cu) or gold (Au) or joined together as in Hydrogen gas H 2 or oxygen gas O 2. We call H 2 and O 2 molecules because they contain more than one atom joined together

20. COMPOUND S These are substances that contain 2 or more different kinds of atoms that are chemically joined or bonded. They cannot be separated using physical methods like filtering, evaporation etc. Compounds can also be called molecules because they contain more than one atom joined together eg. CO 2 H 2 O

21. Chemical Formula The chemical formula is the shorthand way of writing the name of the compound Eg. CuSO 4 means 1 atom of copper Cu 1 atom of sulfur S 4 atoms of oxygen O Eg. (NH 4 ) 2 SO 4 means 2 atoms of nitrogen N 8 atoms of hydrogen H 1 atom of sulfur S 4 atoms of oxygen O

22. NameFormula Atoms in compound No. of each atom Total no. of atoms Carbon dioxide CO 2 Carbon Oxygen 1212 3 WaterH2OH2O Hydrogen Oxygen 2121 3 Salt (sodium chloride) NaCl Sodium chlorine 1111 2 Calcium carbonate CaCO 3 Calcium Carbon Oxygen 113113 5 Hydrochloric acid HCl Hydrogen chlorine 1111 2

23. States of Matter Everything is made of matter. Matter can be found in 3 different states -Solid…..particles very close together -Liquid…particles move apart slightly -Gas…particles are very far apart

24. Changing between the states of matter pg 45 GAS evaporation sublimation energy is added melting LIQUIDSOLID

25. Adding Energy to particles pg 46 Particles have more energy They speed up They move further apart and take up more space They bump into each other and other things more often – more collisions! (Heat things up if you want them to go faster).

26. Changing between the states of matter GAS Condensationsolidification energy is removed freezing LIQUIDSOLID

27. Removing energy from particles Particles have less energy Particles slow down Particles get closer together and take up less room Particles bump into each other less often, so fewer collisions. (Cool things down if you want them to go slower).

28. Changes of State game Water cycle game – stored in 205 (instruction book, game sheets and sets of words included)

29. Diffusion pg 53 A process that causes the particles in a liquid or a gas to spread out evenly Diffusion explains why perfume spreads through a room – or any smell! EXTENSION

30. Ball and Ring experiment Before heating ball could pass through the metal ring easily After heating the metal ball it would not fit through the ring……this is due to EXPANSION, particles had moved apart slightly making the ball a little bigger. When the ball cools down the particles contract (move closer together) so the ball can fit through the ring again. Expansion and Contraction EXTENSION

31. What is Mass? - Mass is the amount of matter in a substance, this doesn’t change where ever you are in the universe. Mass is measured in grams (g) and kilograms (kg). In our everyday language we actually use the word ‘weight’ incorrectly. - Weight is due to the force of gravity acting on us and changes if we move to the moon or another planet. Weight is measured in Newton's (N).

32. Density pg 40 This is the amount of mass packed into a measured volume. Feathers are less dense than gold! Density = mass (g) Volume (mL or cm 3 ) The unit of density = gmL -1 or gcm -3 Density animation http://ippex.pppl.gov/interactive/matter/denslab.html

33. To find the mass of an object use an electronic balance or a triple beam balance. To find the volume of a cube, multiply base x width x height To find the volume of an object with an odd shape, drop it into a measuring cylinder containing water and measure how much the water level goes up by. (1 cm 3 = 1ml) Find the mass and volume of the following objects (for those that float on the water, push them under with the thin piece of copper wire so an accurate measurement can be taken).

34. ObjectMass (g)Volume (cm3) Density Plastic dice Rubber bung Cork bung Marble Metal cube