All 14 Chemistry topics for Edexcel International GCSE, grouped the way the exam is. Each topic has a few flashcards to test yourself; the full sets are free in Socrates AI.
Every paper covers the whole syllabus, so topics are grouped by the specification's content sections.
Name the three states of matter.
Solid, liquid and gas.
What are melting and boiling?
Melting: solid to liquid. Boiling: liquid to gas throughout the liquid, at the boiling point.
What is sublimation?
A solid changing directly into a gas without becoming a liquid.
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What are the three subatomic particles and their charges?
Proton (+1), neutron (0) and electron (−1).
What are the relative masses of protons, neutrons and electrons?
Proton 1, neutron 1, electron about 1/1840 (almost zero).
What do the atomic number and mass number tell you?
Atomic number: number of protons (and electrons in a neutral atom). Mass number: number of protons + neutrons.
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What is relative formula mass (Mr)?
The sum of the relative atomic masses of all the atoms in the formula.
Calculate the Mr of CO₂ (C = 12, O = 16).
12 + 2 × 16 = 44.
Calculate the Mr of CaCO₃ (Ca = 40, C = 12, O = 16).
40 + 12 + 3 × 16 = 100.
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What is an ion?
An atom or group of atoms with an electric charge, formed by losing or gaining electrons.
How does ionic bonding form?
Metal atoms transfer electrons to non-metal atoms, forming positive and negative ions that attract each other strongly.
Describe the ions formed when sodium reacts with chlorine.
Sodium loses one electron to form Na⁺ (2,8); chlorine gains one to form Cl⁻ (2,8,8).
What is electrolysis?
The breakdown of an ionic compound, when molten or in solution, by passing an electric current through it.
What is an electrolyte?
A molten or dissolved ionic compound that conducts electricity.
Which ions go to the cathode and which to the anode?
Positive ions (cations) move to the negative cathode; negative ions (anions) move to the positive anode.
What are the group 1 elements called?
The alkali metals.
Describe how lithium, sodium and potassium react with water.
They float, fizz and move around, producing hydrogen and a metal hydroxide; potassium burns with a lilac flame.
Give the equation for sodium reacting with water.
2Na + 2H₂O → 2NaOH + H₂.
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What is the approximate composition of clean, dry air?
About 78% nitrogen, 21% oxygen, and small amounts of argon, carbon dioxide and other gases.
Name two greenhouse gases.
Carbon dioxide and methane (also water vapour).
How do greenhouse gases warm the Earth?
They absorb infrared radiation emitted from the Earth's surface and re-emit it, trapping heat in the atmosphere.
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Name some metals in order of decreasing reactivity.
Potassium, sodium, calcium, magnesium, aluminium, (carbon), zinc, iron, (hydrogen), copper, silver, gold.
What is a metal displacement reaction?
A more reactive metal displaces a less reactive metal from a solution of its compound.
What happens when iron is put in copper(II) sulfate solution?
Iron displaces copper: a brown coating forms and the blue colour fades; iron sulfate forms.
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What does the pH scale measure?
How acidic or alkaline a solution is, from 0 to 14; 7 is neutral.
What ion do acids produce in water?
Hydrogen ions (H⁺).
What ion do alkalis produce in water?
Hydroxide ions (OH⁻).
What is the test for hydrogen?
A lit splint gives a squeaky pop.
What is the test for oxygen?
It relights a glowing splint.
What is the test for carbon dioxide?
Bubbled through limewater, it turns the limewater milky (cloudy).
What is an exothermic reaction?
A reaction that transfers energy to the surroundings, so the temperature rises.
What is an endothermic reaction?
A reaction that takes in energy from the surroundings, so the temperature falls.
Give two examples of exothermic reactions.
Combustion, neutralisation, respiration and many oxidation reactions.
Name four factors that affect the rate of a reaction.
Temperature, concentration (or pressure for gases), surface area of solids, and catalysts.
What is collision theory?
Reactions happen when particles collide with enough energy (at least the activation energy).
Why does increasing temperature increase the rate?
Particles move faster, so they collide more often and more of the collisions have energy above the activation energy.
What is a reversible reaction?
A reaction in which the products can react to re-form the reactants; shown with the ⇌ symbol.
Give an example of a reversible reaction.
Heating hydrated copper(II) sulfate (blue) gives anhydrous copper(II) sulfate (white) and water; adding water reverses it.
What is dynamic equilibrium?
In a closed system, the forward and reverse reactions happen at the same rate, so the amounts of reactants and products stay constant.
Revise all 21 Reversible reactions and equilibrium flashcards free →
What is a hydrocarbon?
A compound containing hydrogen and carbon only.
What is crude oil?
A mixture of hydrocarbons (mainly alkanes) formed from the remains of ancient marine organisms.
How is crude oil separated?
By fractional distillation: it is heated and vaporised, and fractions condense at different heights in a column with a temperature gradient.
Revise all 27 Organic chemistry and polymers flashcards free →
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