Each halogen has seven outer shell electrons. The most common type of reactions are redox reactions. Each halogen atom is reduced, gaining one electron to form a 1- halide ion with the electron configuration of the nearest noble gas.Cl2 + 2e- → 2Cl-The species that loses the electron is oxidised so the halogens are oxidising agents.The reactivity of the halogen decreases down the group as the tendency to gain electrons decreases.
Group 7 Redox Reactions and Reactivity
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Specification: OCR Chemistry A (H032), AS-level, 3.1.2 Group 2 and 3.1.3 The halogens. Topic: Reactivity Trends.
Key terms in this lesson
- Ion
- A positively or negatively charged atom or group of atoms, formed by the loss or gain of electrons.
- Electron shell
- A main energy level occupied by electrons, given a principal quantum number n, with n = 1 closest to and lowest in energy relative to the nucleus.
- Electron configuration
- The notation showing the arrangement of an atom's electrons in shells and sub-shells, such as 1s2 2s2 2p6.
- Group
- A vertical column of the periodic table, containing elements with the same number of outer-shell electrons.
More in Reactivity Trends
- Reactions of Group 2 Oxides
- Solubility of Group 2 Hydroxides
- Uses of Group 2 Compounds
- Group 7 Halogens Trends in Boiling Points
- Halogen-Halide Displacement Reactions
- Halogen Disproportionation Reactions
- Uses of Halogens
- Test for Halide Ions
All 16 lessons in Reactivity Trends · All OCR AS-level Chemistry topics