InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Which of the following halogens is the most reactive?A. `Cl_(2)`B. `Br`C. `I_(2)`D. `F_(2)` |
|
Answer» Correct Answer - 4 Fluorine is the nost reactive of all the elements in the periodic table. It reacts all the other elements except the lighter noble gars `(He, Ne and Ar)`. It reacts with `Xe` under mild condition to form `Xe` fluorides. Reations of `F_(2)` with many element s are vigorous ,and ofter explosives. In the assive form a few metals such as `Cu, Ni, Fe` and `Al` acquire a protective fluoride coating. However ,if these metals are in powerdered form (with a large suface area) ,or if the reaction mixture is heated ,then the reaction is vigorous. The reactivity of the other halogens decreases in the order `Cl gt Br gt I` .Chlorine and bromine reacts with most of the elements thorugh less vigorously than does fluoride. Iodine is less reacive and does not combine with some elements such as `S` and `Se`. Fluorine and chlorine often oxidize elements further than do bromine and iodine, by this means bringing out ghigher valcances: `PF_(5), PCl_(5), SF_(6)` etc. The great reactivity of fluorine is attributable to two factors: (i) The low bond dissociation enthalpy of the `F-F` bond which results in a low activation energy for the energy. (ii) The very strong bond which are formed. Both of these properties arise form the small size of fluorine. The weak `F-F` bond arises because of repulsion between the lone pair of electons on the two `F` atoms. Strong bonds arise because of the high coordination number `(SF_(6))` and high lattice enthalpy `(CaF_(2))` |
|