AQA GCSE Chemistry Paper 1 Overview

This guide covers topics for Higher and Foundation Tier Chemistry, including:

• Atoms
• Bonding
• Quantitative Chemistry
• Chemical Changes
• Energy Changes

Key Concepts

Substances and Mixtures

• Atoms make up elements; represented by symbols on the periodic table.
• Compounds are two or more different types of atoms chemically bonded (e.g., H2O).
• Mixtures are combinations of different elements and compounds not chemically bonded (e.g., air, saltwater).

States of Matter

• Solid: Particles vibrate in fixed positions.
• Liquid: Particles are touching but free to move.
• Gas: Particles are far apart and move randomly.
• Phase changes are physical changes, not chemical reactions.

Balancing Equations

• Chemical reactions are represented with word and symbol equations.
• Atoms are not created or destroyed in reactions; equations must balance.
• Balance compounds before elements, starting with ones involving less complex molecules.

Atomic Structure and the Periodic Table

Atomic Models

• JJ Thompson: Plum pudding model.
• Ernest Rutherford discovered the nucleus.
• Niels Bohr: Electrons exist in shells.
• James Chadwick: Discovered neutrons.

Periodic Table

• Atomic Number: Number of protons, determines the element.
• Mass Number: Protons + neutrons.
• Isotopes: Same element, different neutrons.

Electron Configuration

• Electrons are arranged in shells (e.g., 2, 8, 8, 2 for calcium).

Periodicity and Groups

• Metals donate electrons, non-metals accept electrons.
• Group 1: Alkali metals, increase in reactivity down the group.
• Group 7: Halogens, decrease in reactivity down the group.
• Group 0: Noble gases, unreactive.

Chemical Bonding

Metallic Bonding

• Metal atoms in a lattice with delocalized electrons, conduct electricity.

Ionic Bonding

• Metal and non-metal bond; e.g., NaCl.
• Ionic compounds have high melting/boiling points and conduct electricity when liquid or dissolved.

Covalent Bonding

• Non-metals share electrons to form molecules (e.g., O2 has a double bond).
• Simple molecular structures have low boiling points.
• Giant covalent structures are strong (e.g., diamond, graphite).

Quantitative Chemistry

Moles

• Mole: A unit for amount of substance.
• Moles = Mass / Molar Mass.

Stoichiometry

• Balance equations using mole ratios.
• Predict amounts of reactants/products using balanced equations.

Reactions and Calculations

• Limiting reactant: Determines amount of product.
• Concentration: Moles of solute per volume of solution.

Chemical Changes

Reactivity Series

• More reactive metals displace less reactive metals from compounds.
• Extraction: Metals less reactive than carbon can be extracted by smelting.

Acids and Bases

• Strong acids: Completely dissociate in solution.
• Weak acids: Partially dissociate.
• Neutralization: Acid + base = salt + water.

Energy Changes

Exothermic vs Endothermic

• Exothermic: Releases energy; temperature increase.
• Endothermic: Absorbs energy; temperature decrease.

Energy Profiles

• Potential energy diagrams show reactants/products energy.

Electrolysis

Process

• Decomposition using electricity.
• Used for metal extraction (e.g., aluminium).

Products

• Cathode: Reduction (gain electrons).
• Anode: Oxidation (lose electrons).

Triple Only Topics

Atom Economy

• Efficiency of mass in reactions.
• Percentage yield: Actual yield vs theoretical yield.

Titrations

• Determine concentration of a solution.
• Use of indicators and volumetric analysis.

Fuel Cells

• Convert chemical energy to electrical energy using hydrogen.

These notes cover the essential topics for AQA GCSE Chemistry Paper 1. Remember to focus on understanding the concepts and practicing equation balancing, stoichiometry, and chemical calculations for success on the exam.