Atomic Foundations of Matter
Class 9 · Science
3 ideas in Class 9 Science, explained in plain words, with games and quizzes to practise.
Conservation and Composition
Part of: Conservation and Composition
During a chemical change, atoms rearrange, so the total mass stays the same in a closed system. A compound also contains its elements in a fixed mass ratio, whatever its source.
Why it matters. These patterns help distinguish a chemical compound from a mixture and explain why an open setup can seem to lose mass.
Try it in two minutes
- Dissolve a little salt in water and compare the closed container before and after.
- Discuss what happens if gas can escape.
- Compare the same compound from different sources.
Try at home. Look for a sealed container when discussing mass changes during reactions.
Molecules, Ions and Bonds
Part of: Molecules, Ions and Bonds
Atoms can share electrons to form covalent bonds or transfer electrons to form oppositely charged ions. A molecule is a neutral group of atoms that can exist independently.
Why it matters. Knowing how bonds form helps explain why substances have different particle arrangements and properties.
Try it in two minutes
- Use dots or small counters to represent outer electrons.
- Show two atoms sharing a pair.
- Then model one atom giving an electron to another.
Try at home. When you see a formula, count which atoms are present before naming the bond type.
Formulas and Particle Mass
Part of: Formulas and Particle Mass
A chemical formula shows the kinds and relative numbers of atoms or ions. Molecular mass is found by adding the atomic masses in a molecule; ionic compounds use formula-unit mass.
Why it matters. Formula reading connects particle structure with composition and gives a way to compare masses.
Try it in two minutes
- Write a simple formula with counters for each atom.
- Add the listed atomic masses.
- Compare a molecule with an ionic formula unit.
Try at home. Practise counting subscripts and parentheses in familiar formulas.
What your child will practise
- Conservation and Composition: Desert Puzzle (Clue Puzzle)
- Conservation and Composition: Mission Control Quest (Collect the Answer)
- Conservation and Composition: Ocean Quick Fire (Quick Fire)
- Formulas and Particle Mass: Jungle Quick Fire (Quick Fire)
- Molecules, Ions and Bonds: Lab Explorer Sort (Sort It Out)
- Quiz: Conservation and Composition (8 questions)
- Quiz: Formulas and Particle Mass (8 questions)
- Quiz: Molecules, Ions and Bonds (8 questions)