Grade 8 · Science · Unit 2 of 22
Particles & Matter
Kinetic theory and the atom
What your child practises
How the movement of particles explains solids, liquids and gases and changes of state, the parts of an atom (including the quarks inside protons and neutrons, and electrons as leptons), elements and compounds, and telling physical from chemical changes.
Alberta Curriculum learning outcome: Unit A: Mix and Flow of Matter · pure substances, mixtures and the particle model of matter
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Which is a physical change?
- Milk turning sour
- Ice melting
- Wood burning
- Iron rusting
Show answer
Ice melting
Hint: In a physical change, no new substance forms.
Question 2
Why do scientists keep changing their models of the atom?
- Old models were never tested.
- Atoms change shape every year.
- New evidence shows something the old model cannot explain.
- Scientists vote on a new model each decade.
Show answer
New evidence shows something the old model cannot explain.
Hint: A model is the best explanation we have so far. It is revised when experiments give new evidence.
Question 3
An atom's centre is called the…
- molecule
- nucleus
- electron
- shell
Show answer
nucleus
Hint: The nucleus holds protons and neutrons.
Question 4
Which particle has a negative charge?
- electron
- nucleus
- neutron
- proton
Show answer
electron
Hint: Electrons are negative, protons positive and neutrons have no charge.
Question 5
Why does a gas get compressed more easily than a solid?
- Gas particles are stuck together.
- Gas particles have no mass.
- Gas particles are heavier.
- There is lots of empty space between gas particles.
Show answer
There is lots of empty space between gas particles.
Hint: Particles in a gas are far apart, so they can be pushed closer.
Question 6
Physical change or chemical change? Sort each example.
Sort into: 🧊 Physical change · 🔥 Chemical change
- 🧊ice melts
- 🫧baking soda fizzes in vinegar
- ♨️water boils into steam
- 🔩an iron nail rusts
- 🪵a log burns
- 🥛a glass is smashed
- 🧂salt dissolves in water
- 🍳an egg cooks
Show answer
🧊 Physical change: ice melts, water boils into steam, a glass is smashed, salt dissolves in water · 🔥 Chemical change: baking soda fizzes in vinegar, an iron nail rusts, a log burns, an egg cooks
Hint: In a physical change the substance stays the same (just a different shape or state). In a chemical change a new substance forms.