Cambridge IGCSE Chemistry (0620) Syllabus Flashcards

Comprehensive practice flashcards covering core and extended topics from the Cambridge IGCSE Chemistry (0620) syllabus for examination in 2026, 2027, and 2028.

What are the three assessment objectives (AOs) in Cambridge IGCSE Chemistry 0620 and their overall percentage weightings?

AO1 Knowledge with understanding ($50\%$), AO2 Handling information and problem-solving ($30\%$), and AO3 Experimental skills and investigations ($20\%$).

How does relative molecular mass ($M_r$) affect the rate of diffusion of gases?

Gases with a lower relative molecular mass diffuse faster than gases with a higher relative molecular mass.

What is the definition of isotopes?

Different atoms of the same element that have the same number of protons but different numbers of neutrons.

Why do isotopes of the same element have identical chemical properties?

They have the same number of electrons and therefore the same electronic configuration.

How is relative atomic mass ($A_r$) defined in the syllabus?

The average mass of the isotopes of an element compared to $\frac{1}{12}\text{th}$ of the mass of an atom of $^{12}\text{C}$.

What is the value of the Avogadro constant and what does one mole represent?

One mole is the unit of amount of substance containing $6.02 \times 10^{23}$ particles (atoms, ions, or molecules).

What is the volume occupied by one mole of any gas at room temperature and pressure (r.t.p.)?

$$24\,\text{dm}^3$$

What is the definition of electrolysis?

The decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current.

What products are formed at the anode and cathode during the electrolysis of molten lead(II) bromide using inert electrodes?

Lead is formed at the cathode (reduction) and bromine is formed at the anode (oxidation).

What is the only chemical product produced by a hydrogen–oxygen fuel cell?

Water ($\text{H}_2\text{O}$).

How is activation energy ($E_a$) defined?

The minimum energy that colliding particles must have to react.

In terms of energy changes, what are bond breaking and bond making?

Bond breaking is an endothermic process ($\Delta H$ is positive), and bond making is an exothermic process ($\Delta H$ is negative).

What two conditions define a reversible reaction at dynamic equilibrium in a closed system?

1. The rate of the forward reaction equals the rate of the reverse reaction.
2. The concentrations of reactants and products are no longer changing.

What are the typical conditions and catalyst used for the Haber process to manufacture ammonia?

A temperature of $450\,^\circ\text{C}$, a pressure of $20\,000\,\text{kPa}$ ($200\,\text{atm}$), and an iron catalyst.

What are the typical conditions and catalyst used in the Contact process for converting sulfur dioxide to sulfur trioxide?

A temperature of $450\,^\circ\text{C}$, a pressure of $200\,\text{kPa}$ ($2\,\text{atm}$), and a vanadium(V) oxide catalyst.

How are oxidation and reduction defined in terms of electron transfer and oxidation number?

Oxidation is the loss of electrons and an increase in oxidation number; reduction is the gain of electrons and a decrease in oxidation number.

How are acids and bases defined in terms of proton transfer?

Acids are proton donors ($\text{H}^+$ donors) and bases are proton acceptors ($\text{H}^+$ acceptors).

What is an amphoteric oxide, and what two oxides are classified as amphoteric in the syllabus?

An oxide that reacts with both acids and bases to produce a salt and water; examples are $\text{Al}_2\text{O}_3$ and $\text{ZnO}$.

What are the physical appearances of chlorine, bromine, and iodine at r.t.p.?

Chlorine is a pale yellow-green gas, bromine is a red-brown liquid, and iodine is a grey-black solid.

What is the order of metals and reference elements in the reactivity series from most reactive to least reactive?

Potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold.

Why does aluminium appear to be unreactive despite being high in the reactivity series?

It forms a tough, protective oxide layer on its surface that prevents further reaction.

What are the required conditions for the rusting of iron and steel?

The presence of both oxygen and water.

What is the main ore of aluminium and which process is used to extract the metal?

Bauxite, and the aluminium is extracted by electrolysis.

What is the composition of clean, dry air?

Approximately $78\%$ nitrogen ($\text{N}_2$), $21\%$ oxygen ($\text{O}_2$), and the remainder is a mixture of noble gases and carbon dioxide ($\text{CO}_2$).

What is the balanced symbol equation for photosynthesis?

$$6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$$

How do the physical properties of fractions change from the bottom to the top of a petroleum fractionating column?

Decreasing chain length, higher volatility, lower boiling points, and lower viscosity.

How can saturated and unsaturated hydrocarbons be distinguished using aqueous bromine?

Unsaturated hydrocarbons decolourise aqueous bromine (orange/brown to colourless), whereas saturated hydrocarbons show no rapid reaction and remain orange/brown.

Which synthetic polymer structure is represented in this diagram?

Nylon, a polyamide.

Which synthetic polymer structure is represented in this diagram?

PET, a polyester.

What type of monomer is represented by this general chemical structure?

An amino acid monomer (where R represents different side-chains).

What natural polymer structure is represented in this diagram?

Protein (a natural polyamide).

How is the $R_f$ value calculated in paper chromatography?

$$R_f = \frac{\text{distance travelled by substance}}{\text{distance travelled by solvent}}$$

What are the test results when testing for chloride ($\text{Cl}^-$), bromide ($\text{Br}^-$), and iodide ($\text{I}^-$) ions with dilute nitric acid and aqueous silver nitrate?

Chloride forms a white precipitate, bromide forms a cream precipitate, and iodide forms a yellow precipitate.

What is the qualitative test and positive result for sulfate ions ($\text{SO}_4^{2-}$) in solution?

Acidify with dilute nitric acid, then add aqueous barium nitrate; a white precipitate is produced.

What are the qualitative chemical tests and results for hydrogen ($\text{H}_2$) and oxygen ($\text{O}_2$) gases?

Hydrogen 'pops' with a lighted splint; oxygen relights a glowing splint.

What are the characteristic flame test colours for $\text{Li}^+$, $\text{Na}^+$, $\text{K}^+$, $\text{Ca}^{2+}$, $\text{Ba}^{2+}$, and $\text{Cu}^{2+}$?

$\text{Li}^+$: red; $\text{Na}^+$: yellow; $\text{K}^+$: lilac; $\text{Ca}^{2+}$: orange-red; $\text{Ba}^{2+}$: light green; $\text{Cu}^{2+}$: blue-green.