Give reason s for each of the following : (i) Transtion metal fluorides are ionicin nature whereasbromides and chlorides are usually covalent in nature. (ii) Chemistry of all the lanthanoids is quite similar.

Give reason s for each of the following : (i) Transtion metal fluorid

1.	Give reason s for each of the following : (i) Transtion metal fluorides are ionicin nature whereasbromides and chlorides are usually covalent in nature. (ii) Chemistry of all the lanthanoids is quite similar.
Answer» Solution :(i) As electronegativity of halogens decreases in the order `F gt Cl gt BR`, the ionic character of transition metal HALIDES decreases in the order `M- F gt M -Cl gt M-Br` . Hence, fluorides are ionic whereas CHLORIDES and bromides are covalent. (ii) The change in the SIZE of the lanthanoids due in langthanoid contraction is very small as we proceed from`L a( Z =57)` to `Lu ( Z= 71)` . Hence, their chemical propertiesare similar. Moreover, their valence shell configuration remains the same because the electrons are added into the inner 4 f-subshell. Hence, they show similar chemical properties.