Atoms, periodic table and reactions

Science understanding — Australian Curriculum v9.0, Year 10 Science.

Achievement focus

Students explain patterns and trends in the periodic table and predict products of reactions and the effect of changing reactant and reaction conditions.

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AC9S10U06 — Structure, properties and the periodic table

Students learn to: explain how the structure and properties of atoms relate to the organisation of the elements in the periodic table.

Core ideas

• Electron shells and valence electrons influence reactivity and bonding; atomic number orders elements.
• Trends (e.g. across a period or down a group) connect to atomic radius, ionisation energy, and metallic/non-metallic character where appropriate at Year 10 level.

Learning checkpoints

1. Why do elements in the same group often show similar chemical properties?
   Sample answer: They have the same number of valence electrons, which governs how they tend to bond and react.

2. How does atomic number define an element?
   Sample answer: It is the number of protons in the nucleus; changing proton number changes the element.

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AC9S10U07 — Reaction types and rates

Students learn to: identify patterns in synthesis, decomposition and displacement reactions and investigate factors that affect reaction rates.

Core ideas

• Synthesis (combination): two or more reactants form a product. Decomposition: one substance breaks into simpler products. Displacement: a more reactive element replaces another in a compound (activity series applies).
• Rate can be influenced by concentration, temperature, surface area, catalysts, and (for some systems) pressure.

Learning checkpoints

1. Classify: .
   _Sample answer:_ Synthesis (combination).

2. Give two ways to speed up many classroom reactions without changing the identity of the reactants.
   Sample answer: Increase temperature; use finer powder or smaller pieces to increase surface area; increase concentration where safe and appropriate.