3.3.3 - Group 7 Flashcards
What does fluorine look like?
Pale yellow gas
What does chlorine look like?
Green gas
What does bromine look like?
Red-brown liquid
What does iodine look like?
Black solid
The size of the halogens _____ down the group
The size of the halogens increases down the group
Mpts/bpts of the halogens _____ down the group. Why?
The mpts/bpts of the halogens increases down the group. More electrons -> stronger vdWs’ forces between molecules
Bond enthalpies generally ______ down group 7. Exception - why?
Bond enthalpies generally decrease down group 7. Exception - fluorine. Because of fluorine’s very small size, non-bonding electrons repel each other from each atom.
How do halogens react? E.g. Cl?
They gain one electron each to form -1 ions (become reduced).
E.g. Cl2 + 2e- -> 2Cl-
Halogens usually act as ______ agents
Oxidising agents (themselves gain an electron so are reduced)
What is the trend in oxidising power down group 7?
Oxidising power decreases down group 7
What is the trend in reducing power down group 7?
Reducing power increases down group 7
In solution, a halogen will replace a less reactive halide in solution. T/F?
True: in solution, a halogen will replace a less reactive halide in solution. E.g. if the halide ion is below the halogen in the periodic table.
Define ‘electronegativity’
The power of an atom to attract the shared electrons towards itself in a covalent bond
Trend in electronegativity down group 7?
Electronegativity decreases down group 7
How do you test for halide ions?
1 - Add dilute HNO3 (aq) to react with any CO3^2- or OH- (that would cause a false positive). 2 - Add AgNO3 (aq) Ppts form 3 - Add dilute NH3 (aq) 4 - Add conc NH3 (aq)
