1. What is the Conservation of Mass?

2. Learning Objectives
Aiming for 4: Define the use of a normal script number before a chemical formula and a subscript number within a formula.
Aiming for 6: Use multipliers in equations in normal script before a chemical formula and subscript within a formula.
Aiming for 8: Balance complex equations and add state symbols.

3. Demonstration
Answer the following questions relating to the demonstration:
1. Has a chemical reaction occurred? (Explain what you can see to support your answer)
2. Complete the word equation:
potassium iodide + lead nitrate → ______________ + ___________
3. Comment on the results.
A colour change has occurred which symbolises a reaction has taken place
potassium nitrate lead iodide
Although at some degree of accuracy the experiment appears to show a mass change this is within the limits of experimental error.

4. What is the Conservation of Mass?
Think, pair, share
Watch the video clip
Now edit your understanding of the question and add extra detail in a DIFFERENT COLOURED PEN.

5. Modelling kit practice!
Aiming for 4-6: Make a molecule of hydrogen, oxygen and carbon dioxide
Aiming for 6-9: Make a molecule of carbon dioxide, water, methane and trichloromethane
Question: What is the relative formula mass of each of these molecules?

6. Subscript and Superscript
Subscript: H2O – The small 2 symbolises there are 2 hydrogen atoms in this molecule. The number is always AFTER the element that it refers to. Superscript: Mg2+ - The small 2+ states how many electrons the ion has lost or gained. In this case the magnesium ion has lost 2 electrons (negatively charged) leaving an overall positive charge. SO42- Write down the number of S and O atoms in this ion and the overall charge!

7. Balancing Equations
2Li + 2H2O  2LiOH + H2 The large number in front of the symbol indicates how many of that molecule there are. Use the modelling kit or draw molecular diagrams to represent this reaction.

8. Balancing Equations
Aiming for 4: Use the modelling kit and balancing equations 1 worksheet
Aiming for 6: Use the modelling kit and balancing equations 2 & 3 worksheets
Aiming for 8: Use the balancing equations 4 & 5 worksheet
CHALLENGE: Using your knowledge of ions and reactivity of metals, write some of your own balanced equations.

9. Plenary: Reflection Question
If you were going to teach this lesson to ​younger students, what would you identify ​as the key things they would need to ​know? Highlight these things in the work done today!