AQA GCSE Chemistry 8462: The periodic table – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions cover section 4.1.2 The periodic table (4.1.2.1 to 4.1.2.6) of the AQA GCSE Chemistry (8462) specification, for teaching from September 2016 and exams from June 2018 onwards. The section is assessed on Paper 1, set at Foundation and Higher Tier. It has no (HT only) statements; question 9(c) asks for an ionic equation, a skill the specification marks (HT only), and is labelled (Higher). There is no required practical in this section.

Learn the content first in the periodic table study guide and the revision notes. For questions on the rest of topic 4.1 (atomic models, isotopes, separating mixtures), use the Atomic structure practice questions. The course hub is AQA GCSE Chemistry, and the printable checklist lists every point.

Relative atomic masses: K = 39, I = 127.

Questions

1. An atom of element X has the electronic structure 2,8,8,2. State the period and the group of X in the periodic table. [2]

2. Three elements are described below.

• Element A is a shiny solid that conducts electricity and forms A²⁺ ions in its compounds.
• Element B is a dull, brittle yellow solid that does not conduct electricity. Its oxide dissolves in water to give an acidic solution.
• Element C is a gas. In its compound with sodium it is present as C⁻ ions.

Classify each element as a metal or a non-metal. [3]

3. Tellurium has atomic number 52 and relative atomic mass 127.6. Iodine has atomic number 53 and relative atomic mass 126.9. The most common isotopes of tellurium are tellurium-128 and tellurium-130. The only natural isotope of iodine is iodine-127.

Explain why tellurium is placed before iodine in the modern periodic table, even though its relative atomic mass is higher. [3]

4. Mendeleev predicted the properties of an undiscovered element he called eka-aluminium. Gallium was discovered a few years later.

Property	Prediction for eka-aluminium	Gallium
Relative atomic mass	68	69.7
Density in g/cm³	6.0	5.91
Melting point	Low	29.8 °C

(a) Calculate the percentage difference between the predicted and measured densities, using the measured value as the reference. Give your answer to 2 significant figures. [2] (b) Explain how the discovery of gallium supported Mendeleev’s periodic table. [2]

5. The table shows the boiling points of four noble gases.

Noble gas	Neon	Argon	Krypton	Xenon
Boiling point in °C	−246	−186	−152	−107

(a) Radon is below xenon in Group 0. Predict a boiling point for radon. [1] (b) Helium has only two electrons in its outer shell but is placed in Group 0, not Group 2. Explain why. [2] (c) Describe the relationship between relative atomic mass and boiling point shown by the noble gases. [1]

6. This question is about the reactions of the first three alkali metals.

(a) A small piece of sodium is placed in a trough of water containing universal indicator. Describe three things you would see. [3] (b) Write a balanced symbol equation for the reaction of lithium with oxygen. [2] (c) Potassium reacts with chlorine. Name the product and state its appearance. [1]

7. The boiling points of three Group 1 elements are lithium 1342 °C, sodium 883 °C and potassium 759 °C.

(a) Predict the boiling point of rubidium. [1] (b) Write a balanced symbol equation for the reaction of caesium with chlorine. [2] (c) Explain, in terms of electrons, why caesium chloride has the same type of formula as sodium chloride. [2]

8. Halogens react with both metals and non-metals.

(a) Hydrogen reacts with chlorine. Name the product and state the type of bonding in it. [2] (b) Potassium reacts with iodine. Name the product, state the type of compound formed and give the charge on the halide ion. [2] (c) Calculate the relative formula mass, Mr, of the compound formed in (b). [1]

9. A student adds solutions of halogens to solutions of sodium halides. A tick means a colour change was seen.

Halogen added	Sodium chloride	Sodium bromide	Sodium iodide
Chlorine	–	✓	✓
Bromine	✗	–	✓
Iodine	✗	✗	–

(a) Use the results to put chlorine, bromine and iodine in order of reactivity, most reactive first. Explain how the results show this. [2] (b) Write a word equation and a balanced symbol equation for the reaction of chlorine with sodium bromide. [2] (c) (Higher) Write the ionic equation for the reaction in (b). [1] (d) State the colour the sodium bromide solution turns when chlorine is added. [1]

10. Astatine is the element below iodine in Group 7. Very little astatine has ever been made.

Use trends in Group 7 to predict the properties of astatine and how it would behave with potassium iodide solution. Explain your predictions. [6]

11. Describe the steps by which the periodic table developed, from the earliest tables to the modern table. Explain how evidence was used at each stage. [6]

Answers

1. Four occupied shells, so period 4 [1]. Two outer electrons, so Group 2 [1]. Examiner insight: Each mark needs the number linked to the right word; “4, 2” with no labels can lose both marks if they are in the wrong order.

2. A: metal (it forms positive ions) [1]. B: non-metal (does not conduct; acidic oxide) [1]. C: non-metal (forms negative ions) [1]. Examiner insight: The deciding evidence is the type of ion formed; shininess alone would not be enough, since some non-metals (iodine, graphite) look shiny.

3. Elements are placed in order of atomic (proton) number, and tellurium (52) has fewer protons than iodine (53) [1]. Relative atomic mass is an average of the masses of an element’s isotopes, allowing for abundance [1]. Tellurium’s common isotopes are heavier (128 and 130) than iodine’s only isotope (127), so tellurium’s average is higher [1]. Examiner insight: The third mark needs the comparison of isotope masses; “tellurium has more neutrons” alone is too vague to score.

4. (a) (6.0 − 5.91) ÷ 5.91 × 100 [1] = 1.5% [1]. (b) Mendeleev’s predictions were made before gallium was discovered [1]; the measured properties were close to his predictions, so the idea behind his table (gaps for undiscovered elements) was supported [1]. Examiner insight: In (a) a bare 1.5% earns both marks only if correct; showing the subtraction and division secures the method mark if you slip on the arithmetic.

5. (a) Any value higher than −107 °C, e.g. about −60 °C [1]. (b) Helium’s outer shell is the first shell, which is full with two electrons [1], so it has a stable arrangement and is unreactive like the other noble gases [1]. (c) Boiling point increases as relative atomic mass increases [1]. Examiner insight: For (a) the mark is for following the trend; a value at or below −107 °C scores zero however it is justified.

6. (a) Any three from: sodium floats [1]; melts into a ball [1]; fizzes / bubbles of gas [1]; moves about on the surface; gets smaller and disappears; indicator turns purple. (b) Correct formulae, 4Li + O₂ → 2Li₂O [1]; correctly balanced [1]: 4Li + O₂ → 2Li₂O. (c) Potassium chloride, a white solid [1]. Examiner insight: “Hydrogen is produced” is a conclusion, not an observation, so it does not score in (a); write “fizzing” or “bubbles”.

7. (a) Any value below 759 °C, e.g. about 700 °C [1]. (b) Correct formulae, Cs + Cl₂ → CsCl [1]; balanced: 2Cs + Cl₂ → 2CsCl [1]. (c) Caesium and sodium are both in Group 1 with one outer electron, so both form 1+ ions [1]. Chloride ions have a 1− charge, so the ions combine 1 : 1, giving MCl [1]. Examiner insight: An unbalanced equation with correct formulae still earns the first mark in (b), but changing a formula to balance it (writing CsCl₂) loses both.

8. (a) Hydrogen chloride [1]; covalent bonding (shared pairs of electrons) [1]. (b) Potassium iodide, an ionic compound [1], containing iodide ions with a 1− charge [1]. (c) Mr of KI = 39 + 127 = 166 [1]. Examiner insight: “Iodine” for the product name, or “iodine ion”, is not credited; the ion is iodide.

9. (a) Order: chlorine > bromine > iodine [1]. Chlorine displaces both bromine and iodine, bromine displaces only iodine, and iodine displaces neither [1]. (b) chlorine + sodium bromide → sodium chloride + bromine [1]; Cl₂ + 2NaBr → 2NaCl + Br₂ [1]. (c) Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂ [1]. (d) Orange (yellow-orange is accepted) [1]. Examiner insight: In (a) the order alone gets one mark; the second needs the evidence from the table, not a recalled explanation about electrons.

10. Indicative points, one mark each:

• Astatine would be a solid at room temperature [1]
• with a higher melting point than iodine, because its molecules are larger and the forces between them are stronger [1]
• and a dark (black) colour, continuing the darkening trend [1].
• It would be less reactive than iodine [1]
• because its outer shell is further from the nucleus, so an extra electron is attracted less strongly [1].
• So it would not displace iodine from potassium iodide solution; no colour change [1].

Examiner insight: AQA marks 6-mark extended responses by levels, so a list of predictions without the explanations stays in the lower level; link each prediction to its reason.

11. Indicative points, one mark each:

• Early tables put elements in order of atomic weight, because protons, neutrons and electrons were not yet known [1].
• These tables were incomplete, and strict order placed some elements in inappropriate groups [1].
• Mendeleev left gaps for elements not yet discovered, keeping similar elements in the same group [1].
• He changed the order in some places to fit properties, e.g. tellurium before iodine [1].
• Elements he predicted, such as gallium and germanium, were discovered with properties close to his predictions, which supported his table [1].
• The discovery of isotopes (and atomic number) explained why atomic-weight order was sometimes wrong; the modern table uses atomic number [1].

Examiner insight: Under levels marking, the steps must be in a logical sequence; isolated facts about Mendeleev without the role of evidence and isotopes keep the answer out of the top level.

Where marks are usually lost

• Reading group from the number of shells and period from the outer electrons, the wrong way round.
• Classifying an element as a metal because it is shiny or a solid, instead of using the type of ion it forms.
• Explaining tellurium and iodine with “Mendeleev made a mistake” rather than isotopes and atomic number.
• Giving “hydrogen gas given off” as an observation; examiners want what you see (fizzing, bubbles).
• Writing CsCl₂, KI₂ or Li₂O₂; check the ion charges before writing a formula.
• Naming halide ions as “chlorine ion” or “iodine ion”.
• Using the Group 1 reactivity explanation for Group 7 without changing “lose” to “gain”.
• Predicting a trend value outside the range set by the data.
• Stating an order of reactivity without quoting the results that show it.

Next steps

• Revise from the periodic table revision notes.
• Reread any weak section in the periodic table study guide.
• Practise the rest of topic 4.1 with the Atomic structure practice questions.
• Return to the AQA GCSE Chemistry hub and tick off points on the printable checklist.
• Try one of the free diagnostics to find your next gap.
• Book a free trial class.

Official syllabus

AQA GCSE Chemistry (8462) specification, Version 1.1 (October 2019), for teaching from September 2016 and exams from June 2018 onwards (AQA), section 4.1.2 The periodic table (4.1.2.1 to 4.1.2.6).