Rashid School for Boys. Year 7 Science. Particles. Name: Form:

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1 Rashid School for Boys Year Science Particles Name: Form: 1

2 By the end of this topic.. Unit Particles Level 3 I know that ice melts when it gets too warm and that liquid water turns into solid water (ice) when it gets too cold. I can say that ice is a solid, milk is a liquid and air is a gas. Level 4 I can group a range of materials into solids, liquids & gases. I know that when water is heated or cooled the change involved is reversible. I know that solids have a fixed shape and you cannot walk through them; liquids change shape and can be walked through; gases have no fixed shape and can easily be walked through. I can group things like: treacle, flour, and, salt. I know that all materials are made of particles: in a solid the particles are arranged in rows very close each other vibrating, in a liquid the particles are arranged randomly, very close to each other but they can move more freely, in a gas the particles are working freely and have lots of space between them. Level 5 I know the particle theory of matter including how heat affects the movement of the particles. I can understand why different materials are used for different jobs 2

3 Physical States Sheet 1a All substances are in the form of either a solid, liquid or gas. These are known as physical states. SOLIDS Carry out the following experiments: Feel how heavy it is Feel how hard it is Can you see through it? Answer these questions: 1. Does a solid change shape on its own?. 2. Does a solid always take up the same amount of space?. 3. Can you see through all solids?.. LIQUIDS Measure 100 cm 3 water into the measuring cylinder. Pour it into the flask ( every drop!) Pour the water from the flask into the beaker ( every drop!) Pour the water from the beaker into the measuring cylinder. Measure its volume. 3

4 Physical States 1. Does a liquid change shape? 2. Does a liquid always have the same volume?... GASES You must wear safety goggles for this experiment, Heat a few crystals of iodine carefully in a test tube as shown. 1. Does the shape of the gas change?.. 2. Does the volume of the gas change? Write the names of some solids, liquids and gases in the table below: SOLID LIQUID GAS SOLIDS: LIQUIDS: GASES: Have a fixed volume and fixed shape. Have a fixed volume and no fixed shape. Have no fixed volume and no fixed shape. 4

5 Mixing substances Sheet 2a Solids, liquids and gases are known as MATTER Carry out the following experiments: In each case you are asked to guess what the result will be. This is known as a PREDICTION. In many experiments you will be asked to make a prediction. 1. If you mix together 50 cm 3 of water and 50 cm 3 of water, predict the total volume: My prediction: cm 3 Actual volume cm 3 2. Mix together 50 cm 3 of peas and 50 cm 3 of sand. Predict the total volume: My prediction: cm 3 Actual volume cm 3 Was your prediction correct? Explain why:.. 3. Now try 50 cm 3 of water and 50 cm 3 of alcohol. My prediction: cm 3 Actual volume cm 3 Explain your results: 5

6 Arrangement of Particles All substances are made up of particles which are too small to be seen even with the most powerful microscope. There are spaces between the particles. How are the particles arranged? The tiny particles are arranged differently in solids, liquids and gases. Look at the models of a solid, liquid and gas and draw how the particles are arranged. Solid Liquid Gas In which of the 3 forms ( solid, liquid or gas ) do you think the spaces between the particles is biggest?.. In which of the 3 forms are the particles moving the fastest?.. The smallest particles are called atoms. When 2 or more of them are joined together, we call them molecules. 6

7 Evidence for Particles Sheet 3a Set up the following experiments. Your teacher may need to help you. For each experiment, draw a diagram to show what happens. Write down approximately how long it takes. Before After

8 Diffusion Fill the balloon with air. Tie a knot in it and make sure that it does not leak. Measure round it and record your measurement. Distance round balloon = Distance after 1 week = cm cm Explain what has happened... Your teacher will set up the tube shown below: has happened after about 15 minutes. On the diagram, show what Is the white gas formed in the middle of the tube? Why not? The movement of particles shown in these experiments is known as DIFFUSION. It is fastest in gases and slowest in solids. 8

9 Changing States Sheet 4a To turn a liquid into a gas you need to increase the movement of the particles. This is done by HEATING. Label the diagram. Measure the temperature of the ice/water mixture before you start heating. Put this down as the temperature at time 0 mins Light the Bunsen burner and half open the air hole. Measure the temperature every minute and record your results on the table provided. Keep heating and recording until the liquid has boiled for 2 minutes, then turn off the Bunsen burner. Time mins Temp o C Time mins Temp o C Results 0 9

10 Interpreting results Using the computer, 1. Plot your results as a line graph. Your teacher will show you how to do it. Make 2 copies of your graph One will be used for display, the other must be stuck in your folder. 2. Draw a labelled diagram of the apparatus you used. 3. Write out the method for the experiment. Stick a copy of the graph in the space below. Look carefully at the graph. What conclusions can you make by looking at its shape? 10

11 Heating solids Sheet 5a Take a ball and ring and check that the ball fits through the ring as shown Heat the ball carefully for 3 minutes in a Bunsen burner. Hold the ball using a pair of tongs. Check to see if the ball fits through the ring. What happens? Why? Heat the bi metallic strip in a Bunsen burner. What happens? When substances are heated they This is because 11

12 Problems of expansion When substances are heated, they expand. This can cause problems. Describe these problems below and explain how they are solved. 1. Expanding railway lines 2. Expanding overhead power cables 3. Expanding concrete in buildings 12

13 Using Expansion Sheet 6a Designing a fire alarm. You will be given the following items: 1. A bi metallic strip 2. A bell and some batteries 3. A nail 4. Some connecting wires and crocodile clips 5. A Bunsen burner Arrange the pieces of apparatus so that they could be used as a fire alarm. Draw a diagram of the electric circuit below. When you have had the circuit checked by your teacher, set it up and see if it works. 13

14 Bi metallic strips How could a bimetallic strip be used in a circuit to make the indicator lights on a car flash? Draw the circuit below to show a bulb, 12v battery, switch and a bi metallic strip. ( clue: when current flows through a bi metallic strip it gets hot ) 14

15 Kinetic Theory Sheet a You should now know that all substances are made from particles. You teacher will show you some models to show that the particles are moving. This is known as the kinetic theory of particles What evidence is there that these particles are moving? How fast do the molecules move? Explain how this model shows the movement of particles in a gas To show a higher temperature, the machine can be made to vibrate more vigorously. What happens to the speed of the particles? What happens to the volume of the gas 15

16 Changes of state When substances change from solids to liquids we need to supply them with energy. We do this by heating them. A pure solid will melt at a particular temperature...this is known as the melting point. It also changes from a liquid to a gas at a particular temperature this is known as the boiling point. Below are some melting points and boiling points of different substances: Melting point o C Boiling point o C Alcohol Water Mercury Lead Oxygen Salt Which of the substances above are: Solids at room temperature (20 o C ) Liquids at room temperature Gases at room temperatue If a substance is PURE it will melt and boil at an exact temperatures. For example PURE ice melts at 0 o C and PURE water boils at 100 o C 16

17 Changes of state When a solid turns to a liquid we call the process melting. This takes place at a definite temperature ( the melting point ). When a liquid turns into a solid we call the process freezing. This takes place at the same temperature as melting. A liquid turns into a gas ( boils ) and the gas turns back into a liquid ( condenses ) at the same temperature. What is the boiling point of pure water? What is the melting point of pure ice? Is a substance solid, liquid or gas at room temperature? To work this out we need to know 3 things: (i) (ii) Room temperature...normally taken as 20 o C or 25 o C The melting point of the substance (iii) The boiling point of the substance If the subtance s melting point AND boiling point are HIGHER than room temperature then the substance is a SOLID If the substance s melting point is lower and its boiling point is higher than room temperature then the substance is a LIQUID If the substance s melting point AND boiling point are LOWER than room temperature then the substance is a GAS 1

18 Solid liquid or gas? Melting point o C Boiling point o C Alcohol Water Mercury Lead Oxygen Salt Which of the substances above are: Solids at room temperature (20 o C ) Liquids at room temperature Gases at room temperatue 18

19 Wordbank Use this page to write down the meanings of any new science words you have come across in this topic. Some suggestions have already been added. Solubility Melting point Diffusion 19

20 Factsheet Go back through the booklet and produce a factsheet to help you revise for the test. Go onto a second page if necessary. 20

21 Factsheet 21

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23 Homework 1 Name 1. A substance has a fixed shape and a fixed volume. Is it a solid, liquid or gas?. 2. A substance has no fixed shape and no fixed volume. Is it a solid liquid or gas? 3. Think of 2 solids, 2 liquids and 2 gases and Complete the table below Name of substance Solid, liquid or gas? What is it used for? 23

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25 Homework 2 Name 1. In the boxes below, draw diagrams to show how particles are arranged in a solid, liquid and gas Solid Liquid Gas 2. How do we change a solid into a liquid? All substances are made of tiny particles which we cannot see. What do we call these particles? Particles are always moving from one place to another. What is the scientific name for movement of particles?. 25

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27 Homework 3 Name 1. A student heated ice cold water in a beaker and measured the temperature every minute. His results are shown below. Use the data in the table to draw a graph of temperature ( on the y axis against time on the x axis. Draw a smooth line of best fit through the points. Time ( mins ) Temperature ( o C )

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29 Homework 4 Name 1. When a substance is heated it gets bigger. What is the scientific name for this process?.. 2. We cannot stop this from happening so we must make sure that things don't break when they get bigger. Draw diagrams to show how we stop these problems with... Railway lines Overhead power cables Bridges 29

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