Equipment Slide 2 printed per student Slide 3 printed per student – optional task Green pens Circus of activities – see technician notes.

Reversible or irreversible? Physical or chemical change? Experiment Reversible or irreversible? Physical or chemical change? How can you tell? What is happening to the particles? Burning toast Ice melting Dissolving sugar Water boiling Cooking an egg Magnesium in acid Bunsen burner on

Retrieval practice 1) What is the missing gap 1. 2) What is missing gap 2. 3) Describe the change of state ‘condensing’ in terms of closeness, arrangement and motion of particles? 4) What state are these at RT? Nitrogen -209.86 -195.79 Osmium 3027 5012 Oxygen -226.65 -182.95 Mercury -38.72 357 1 2

What is happening? Can they be reversed? TWWL: about chemical and physical changes SO THAT I CAN… Identify physical and chemical changes Describe the difference between chemical and physical changes Explain what happens to the particles during chemical and physical changes 14/11/2018 What is happening? Can they be reversed? Energy and direction

Reactions How can we tell if a chemical reaction has happened? Noises Flames or sparks Smells Change in temperature How can we tell if a chemical reaction has happened? Light energy given out Change in colour The mass changes – a gas has escaped Change in colour Bubbles of a gas are made

Reactions Chemical change Physical change In the physical change the molecules look the same but are arranged differently In the chemical change the molecules are different

Chemical or physical? Can you change a raw egg into a cooked egg? Forwards Backwards Can you change a cooked egg into a raw egg? Discuss whether you can go backwards from this previously seen picture. Get students to pronounce irreversible and ask if anyone knows what it is before telling.

Chemical or physical? Can you change water into ice? Forwards Backwards Can you change ice into water? Discuss whether both of these steps are possible.

Reversible or irreversible? Physical or chemical change? Experiment Reversible or irreversible? Physical or chemical change? How can you tell? What is happening to the particles? Burning toast Fireworks Ice cream melting Dissolving sugar Water boiling Cooking an egg Magnesium in acid Melting chocolate Copper sulphate and zinc Bunsen burner on

Rules Task: Write 4 rules to help someone who hasn’t done this lesson work out whether a reaction is: Physical Chemical Irreversible Reversible

Reflection How do you feel about today’s objectives? Choose a face and write why you feel this way (I think I can now _______ because ______________) Identify physical and chemical changes   Describe the difference between chemical and physical changes Explain what happens to the particles during chemical and physical changes.

Optional task

Chemical or physical? The candle has been burning for a while The wax is the fuel Has the wax been used up? Is there any physical or chemical change?