Definitions
Define an atom
The smallest unit of matter; made of protons, neutrons, and electrons.
Write the formula for water and carbon dioxide
H2O, CO2
Name one common acid and one common base.
HCL, NaOH
Write the word equation for a metal + acid reaction.
Metal + acid → salt + hydrogen gas
Name the factors that increases the rate of reaction
temperature, concentration/pressure, surface area, the nature of the reactants, and the presence of a catalyst
Define a compound
A substance made of two or more elements chemically bonded
Write the formula for hydrochloric acid and calcium carbonate
HCL, Ca(OH)₂
Name 3 indicators
Methyl Orange, Purple Cabbage and Litmus
Write the word equation for a combustion reaction
fuel + oxygen → carbon dioxide + water
Explain how surface area affects reaction rate
More surface area → more collisions → faster reaction
Define ionic bonding and covalent bonding
Ionic bonding — transfer of electrons between metal + non‑metal.
Covalent bonding — sharing of electrons between non‑metals.
Write the formula for glucose
C₆H₁₂O₆
Identify whether Ca(OH)₂ is an acid, base, or salt and justify your answer.
Ca(OH)₂ is a base (contains OH⁻ ions)
Explain what a catalyst does in a reaction
A catalyst speeds up reactions by lowering activation energy
Explain collision theory in your own words
chemical reactions occur when reactant particles (atoms, ions, or molecules) collide
Define activation energy and explain its role in reactions
The minimum energy needed to start a reaction.
Given the name magnesium oxide, write its chemical formula and justify it using valency.
MgO (Mg²⁺ + O²⁻ → balanced charges)
Explain why indicators are useful for identifying unknown substances
Indicators translate complex, unseen data into clear, actionable signals, allowing us to monitor health, ensure safety, and make informed decisions
Explain why mass appears to decrease during a reaction
Gas escapes → measured mass decreases even though total atoms remain constant
Interpret a graph showing a fast initial reaction that gradually slows
Graph: steep at start (fast), then flattens (slower as reactants decrease)
Explain the difference between endothermic and exothermic reactions in terms of energy transfer.
exothermic releases energy; endothermic absorbs energy.
Predict the formula of aluminium sulfate using ion charges
Al₂(SO₄)₃
Explain how neutralisation forms salts and give an example with a word equation
Neutralisation is a chemical reaction where an acid and a base cancel each other out to form a neutral solution. The remaining ions join together to form an ionic compound called a salt
Compare decomposition, precipitation, and combustion reactions with examples
Decomposition: one substance → simpler substances
Precipitation: two solutions → solid forms
Combustion: fuel + oxygen → CO₂ + H₂O
Explain how temperature, concentration, surface area, and catalysts interact to influence reaction rate
All four factors increase collision frequency or energy → faster reaction overall