Group 7
- Created by: emma
- Created on: 22-03-14 21:39
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- Group 7
- Atomic radius
- Increases as electrons are added to shells further from nucleus and more sheilding
- Boiling and Melting points
- Increases down group
- Larger molecules and more electrons so greater van der waals between molecules
- Increases down group
- Electronegativity
- The ability of an atom to attract a shared pair of electrons
- Decreases down group
- more shells of electrons so more shielding and further from nucleus
- Less electrostatic force of attraction between outer electron and nucleus
- more shells of electrons so more shielding and further from nucleus
- Physical properties
- F pale yellow gas, reacts with water
- Cl green gas, pale green solution
- Bromine dark red volatile liquid/ brown vapour, orange solution
- Iodine, shiny black solid sublimes to give purple vapour, Brown solution
- Oxidising power of halogens
- Oxidising agents accept electrons
- decreases down group as F has strongest electronegativity
- Test for halide ions
- F
- Cl
- Br
- I
- Add AgNO3 yellow precipitate
- Add dilute NH3 no change
- Add AgNO3 yellow precipitate
- Add AgNO3 cream precipitate formed
- Add dilute NH3 no change
- Add conc NH3 precipitate dissolves
- Add dilute NH3 no change
- I
- Add AgNO3 white precipitate formed
- Add dilute NH3 precipitate dissolves
- Br
- Add AgNO3 no precipitate formed
- Cl
- F
- Reducing power of halide ions
- Reducing agent are species which accept electrons
- Increases down group
- I- has larges atomic radius so weakest electrostatic force of attraction between outer electrons and nucleus
- Increases down group
- Reducing agent are species which accept electrons
- Atomic radius
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