Page 4: Group VII Elements (Part 2)

This page continues the discussion of Group VII elements, focusing on the reactivity of halide ions and chlorine in Group 7 reactions A Level Chemistry. Key points include:

The reducing strength of halide ions increases down the group, which is the opposite trend to the oxidizing ability of the halogens themselves.

Vocabulary: Disproportionation is a type of redox reaction where a species is simultaneously oxidized and reduced.

Definition: A precipitate (ppt) is an insoluble solid that forms and separates from the solution during a chemical reaction.

The page introduces tests for halide ions using silver nitrate solution, which produces characteristic colored precipitates:

• Chloride ions produce a white precipitate
• Bromide ions produce a cream precipitate
• Iodide ions produce a yellow precipitate

Example: The halide ion tests can be used to identify unknown halide salts in solution.

The relative reducing strength of halide ions is demonstrated through their reactions with chlorine water. Chlorine water turns orange with bromide ions and brown with iodide ions, displacing the less reactive halogens.

Highlight: The reactions of halide ions with concentrated sulfuric acid provide further evidence of their relative reducing strengths.

This page provides essential information for understanding halogen chemistry in Group 7 A Level Chemistry OCR and other exam boards.

Page 1: Introduction to Periodicity

This page introduces key concepts in Periodicity Chemistry A Level, including:

The periodic table is organized based on atomic structure, with elements classified into s, p, d, and f blocks. Periodic trends are explained for properties like melting point, boiling point, and atomic radius across Period 3 elements. The page also covers ionization energy trends across periods and down groups.

Definition: Periodicity is the quality or character of being periodic; the tendency to recur at intervals.

Vocabulary: First ionization energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms.

Example: Atomic radius decreases across each period and increases down a group due to changes in nuclear charge and electron shielding.

Highlight: The periodic table's structure reflects electron configurations, with s, p, d, and f blocks corresponding to the orbital types.

A graph illustrates the trend in first ionization energies across the first 20 elements, showing the periodic nature of this property. The page also includes a visual representation of trends in various properties across the periodic table, such as atomic and ionic radii, electronegativity, and melting/boiling points.