S3.1 Exam Practice
The Periodic Table
Section B: Data Analysis
Calculator and Data Booklet permitted.
Question 1: First Ionization Energies Explain
5 marksThe first ionization energies (kJ mol⁻¹) for Period 3:
| Na | Mg | Al | Si | P | S | Cl | Ar |
|---|---|---|---|---|---|---|---|
| 496 | 738 | 578 | 786 | 1012 | 1000 | 1251 | 1520 |
(a) Describe the general trend in first ionization energy across Period 3. [1]
(b) Explain why aluminium has a lower first ionization energy than magnesium. [2]
(c) Explain why sulfur has a lower first ionization energy than phosphorus. [2]
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(a) General increase across the period [1]
(b) Al outer electron is in 3p subshell; Mg outer electron is in 3s [1]; 3p is higher energy/more shielded, easier to remove [1]
(c) P has half-filled 3p³; S has 3p⁴ with one paired electron [1]; electron-electron repulsion in the doubly occupied orbital makes it easier to remove [1]
Question 2: Periodic Trends Define
4 marks(a) Define electronegativity. [1]
(b) Explain the trend in atomic radius across a period. [2]
(c) State the relationship between electronegativity and ionization energy. [1]
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(a) The ability of an atom to attract a bonding pair of electrons in a covalent bond [1]
(b) Atomic radius decreases across a period [1]; effective nuclear charge increases (more protons), pulling electrons closer [1]
(c) Direct/positive relationship; both increase across a period [1]
Section C: Structured Questions
Show all working clearly.
Question 3: Period 3 Oxides Explain
5 marks(a) State the trend in acid-base character of Period 3 oxides. [1]
(b) Write balanced equations for Na₂O and SO₃ reacting with water. [2]
(c) Explain why Al₂O₃ is described as amphoteric. [2]
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(a) Basic → amphoteric → acidic across the period [1]
(b) Na₂O(s) + H₂O(l) → 2NaOH(aq) [1]; SO₃(g) + H₂O(l) → H₂SO₄(aq) [1]
(c) Amphoteric means it can react with both acids AND bases [1]; e.g. Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O AND Al₂O₃ + 2NaOH + 3H₂O → 2Na[Al(OH)₄] [1]
Question 4: Transition Metals Explain
5 marks(a) State two characteristic properties of transition metals (other than colour and catalysis). [1]
(b) Explain why transition metals form coloured compounds. [2]
(c) Explain why transition metals can act as catalysts. [2]
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(a) Any two of: variable oxidation states / form complex ions / magnetic properties [1]
(b) Partially filled d-orbitals split into two energy levels [1]; electrons absorb specific wavelengths of visible light, transmitting the complementary colour [1]
(c) Variable oxidation states allow them to transfer electrons and bind to reactants [1]; provides an alternative pathway with lower Eₐ [1]
Question 5: Successive Ionization Energies HL Deduce
4 marks(a) Sketch the log₁₀ IE pattern for aluminium (13 electrons). [1]
(b) Deduce how to determine an element's group from successive IE data. [2]
(c) Explain the large jump in successive IEs in terms of electron shells. [1]
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(a) Gradual increase for first 3 electrons, then massive jump between 3rd and 4th, then gradual increase [1]
(b) Find the largest jump between successive IEs [1]; the number of electrons removed before this jump = number of valence electrons = group number [1]
(c) The jump occurs when removing an electron from a new inner shell, much closer to the nucleus and less shielded [1]
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