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H1 Chemistry

Chemistry study notes

The Periodic Table

Use electron arrangements and structure to explain trends, reactions and unknown elements.

A-Level 8873, revised syllabus (2026-2027)

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3 topics

  1. Atomic and physical trends

    Change the explanation when the structure changes.

  2. Period 3 compounds

    Compare every required oxide, hydroxide and chloride.

  3. Groups and deduction

    Apply H1 Group 1/17 trends to new evidence.

Scope and references

Learning outcomes and sources

4. The Periodic Table (8873, 2026 revision; examinations 2026 and 2027). Use the outcome map to find the explanation for a particular syllabus requirement.

See the learning outcome map

  1. 4(a) Recognise electronic patterns.

    • Period 3 Na-Cl and Group 17 Cl-I.

    Read the electron pattern across and down

  2. 4(b) Explain radius, first-ionisation and electronegativity trends.

    • (i) Across a period: nuclear charge/shielding.
    • (ii) Down a group: shells/shielding/nuclear charge; atomic and ionic radii.

    Read the electron pattern across and down

  3. 4(c) Explain melting and conductivity across Period 3.

    • Metallic, giant molecular and simple molecular structures.

    A melting-point trend can change its cause

  4. 4(d) Explain halogen volatility.

    • Cl2, Br2, I2; instantaneous dipole-induced dipole attraction.

    A melting-point trend can change its cause

  5. 4(e) Connect Period 3 compounds to their behaviour.

    • (i) Highest oxidation numbers in Na2O, MgO, Al2O3, SiO2, P4O10, SO3 and NaCl, MgCl2, AlCl3, SiCl4, PCl5.
    • (ii) Bonding versus electronegativity; AlCl3 exception.
    • (iii) All six oxides with water.
    • (iv) Acid/base behaviour of six oxides and NaOH, Mg(OH)2, Al(OH)3; amphoterism with NaOH and acids.
    • (v) All five chlorides with water.
    • (vi) Infer oxide/chloride structure from chemical and physical evidence.

    Move from basic oxides to acidic oxidesDissolving and hydrolysing are different processesUse several clues to identify an unknown

  6. 4(f) Compare reducing and oxidising behaviour.

    • (i) Group 1 Li-Cs: ease of electron loss.
    • (ii) Group 17 Cl-I: ease of electron gain.

    Separate losing electrons from gaining them

  7. 4(g) Explain hydrogen-halide thermal stability.

    • HCl, HBr, HI bond energies.

    Separate losing electrons from gaining them

  8. 4(h) Predict properties from group membership.

    • Use periodic patterns with explanations.

    Use several clues to identify an unknown

  9. 4(i) Deduce unknown element identity/position.

    • Combine physical and chemical observations.

    Use several clues to identify an unknown

  • SEAB H1 Chemistry 8873, 2026 revision

    Official scope: section 4, printed pages 14-15. All lettered outcomes and nested requirements checked.

  • SEAB H1 Chemistry 8873, 2027

    Section 4: same substantive outcomes as the revised 2026 course.

  • RI 2022 Periodic Table I (Grail)

    Consulted printed pp. 5, 8-11 and chloride comparison questions for conductivity and oxide/chloride properties. Authored an original combined-evidence deduction; did not adopt the source claim that SiCl4 hydrolysis requires low-lying 3d orbitals.