Welcome to Week 4 of Year 7 Chemistry! This week, we’ll explore the differences between elements and compounds and learn how they combine to form the materials we use every day. You’ll also get hands-on experience with separating mixtures and observing compounds.
Hour 1: Understanding Elements and Compounds
Learning Objectives
By the end of this hour, you will:
Understand what elements and compounds are.
Learn how compounds are formed by chemical bonding.
Read and Watch
Read Chapter 4: "Home Sweet Home" and "The Atmosphere" from "How to Make a Universe with 92 Ingredients". Focus on being able to define what a noble gas is.
Read: pages 33-38 in "What's Chemistry all About?".
Watch: Atomic Hook-Ups (Crash Course). You need to know that there are three types of bonding; knowing their names would be great, but you will be revisiting bonding in years 8 and 9, so you do not need to understand the details yet.
Task: Elements vs. Compounds Chart
Create a two-column chart. Label one column "Elements" and the other "Compounds."
Write three examples of each (e.g., hydrogen, oxygen for elements; water, carbon dioxide for compounds).
Research and describe how compounds are different from mixtures.
Key Concepts
Ionic Bonding: Occurs when one atom transfers electrons to another, forming ions that attract each other (e.g., sodium chloride).
Covalent Bonding: Happens when atoms share electrons to form molecules (e.g., water, H₂O).
Practical Activity: Bonding Models
What You Need:
Mini marshmallows or coloured beads (to represent atoms).
Toothpicks (to represent bonds).
Steps:
Use the marshmallows or beads to represent different elements (e.g., small ones for hydrogen and larger ones for oxygen).
For ionic bonds, create separate positive and negative ions using two different colours, then pair them together.
For covalent bonds, connect two marshmallows/beads with a toothpick to represent shared electrons.
Label your models with the names of the compounds they represent.
Suggested Compounds for Models
Ionic Compounds:
Sodium chloride (NaCl): Sodium (one colour marshmallow/bead) and chlorine (another colour).
Magnesium oxide (MgO): Magnesium and oxygen ions.
Covalent Compounds:
Water (H₂O): Two hydrogens bonded to one oxygen.
Carbon dioxide (CO₂): Two oxygens bonded to one carbon.
Methane (CH₄): Four hydrogens bonded to one carbon.
Task: Reflection Questions
What are the key differences between ionic and covalent bonds?
Why do some atoms transfer electrons while others share them?
Can you think of an example of a compound you use daily that is formed by bonding?
Hour 2: Hands-On Experiment: Separating Mixtures
Learning Objectives
By the end of this hour, you will:
Learn the difference between mixtures and compounds.
Use a simple method to separate a mixture.
Practical Activity: Separate a Mixture
What You Need:
Salt
Sand
Water
A clear glass or jar
Filter paper (or a coffee filter)
A funnel
Steps:
Mix a small amount of sand and salt in a glass of water.
Stir the mixture and observe what happens.
Pour the mixture through the filter paper using the funnel.
Observe what is left in the filter and what passes through.
Reflection Questions:
What did you notice about the sand and salt in the mixture?
How is this different from a compound like water (H₂O)?
Hour 3: Antoine Lavoisier and the Law of Conservation of Mass
Learning Objectives
By the end of this hour, you will:
Learn about Antoine Lavoisier’s contributions to chemistry.
Understand the Law of Conservation of Mass.
Read and Watch
Read: A short biography of Antoine Lavoisier from "100 Scientists that Shaped the World" pages 36-37.
Watch: Conservation of Mass (Ted-Ed) for a quick explanation of his experiments.
Print out the poster.
Task: Conservation of Mass in Action
Write a short paragraph explaining how Lavoisier’s discovery of the conservation of mass changed the way scientists think about chemical reactions.
Reflect: Why is this principle important in modern chemistry?
Quick Activity: Mass Before and After
Measure a small amount of water and dissolve some salt in it.
Weigh the glass before and after dissolving the salt. Does the mass change? Write down your observations.
Summary and Reflection
Reflect on the Week:
What was the most surprising thing you learned about elements and compounds?
How do you think the ability to separate mixtures helps in real-life situations (e.g., water purification)?
Why is the Law of Conservation of Mass important?
Looking Ahead: Next week, we’ll dive into chemical reactions and learn how substances change when they react. Prepare for some exciting experiments with temperature changes and bubbling reactions!
Fantastic work, finishing week 4!
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