Core Periodicity: Chemical Properties
Slide 11 of 31
Reactions and Reactivity of the Halogens
2. A halogen higher up in the periodic table will displace one lower down.
•X2 + 2Y- ® 2X- + Y2
–Chlorine will displace (oxidize) any halide ion below it in the table from a (halide) solution.
•Cl2 (aq) + 2Y-(aq) ® 2Cl-(aq) + Y2 (aq)  Where Y- = Br- or I-
–Bromine will displace (oxidize) iodide ions from a (halide) solution.
•Br2 (aq) + 2I-(aq) ® 2Br-(aq) + I2 (aq)
–Evidence of displacement comes from changes in the appearance of the reaction mixture.
–In other words, fluorine is the strongest oxidizing agent or it is the weakest reducing agent in the group.
3. Just as with the color of the halogens themselves, the color of their precipitates with silver also show a pattern.
–Silver halides are insoluble.
–The color of the halide from AgCl to AgI changes from white to pale yellow to yellow.