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Shyamanjan Bose from GURU NANAK PUBLIC SCHOOL , asked a question
Subject: Chemistry , asked on 11/12/12

why are pentahalides more covalent than trihalides ? can u plz answer it in some easy way , i can 't get the ans. given on the NCERT SOLUTION section.

EXPERT ANSWER

Anita Dahiya ,Meritnation Expert added an answer
Answered on 12/12/12

Covalent bonds are formed as a result of sharing of electrons between two elements. 

In a pentahalide 5 electrons are shared between the two elements whereas, in a trihalide 3 electrons are shared. The higher the number of shared electrons the more covalent the bond becomes. 

Therefore, pentahalides are more covalent in nature as compared to trihalides. 

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Lakhan Kadam , From Kendriya Vidyalaya , added an answer
Answered on 11/12/12

 Pentahalides are more covalent than trihalides because pentahalides took more energy to overcome the bond enthalpy as compared with the trihalides. Pentahalides cannot lose electron easily so they form bond by mutual sharing and thus the bond forms covalent, whereas the trihalides can lose electron easily as compared to pentahalides, making the bond less covalent.

Abhijit Gope , From Army Public School Tezpur , added an answer
Answered on 11/12/12

@lakhan where did U find this concept ?? made ur own hypothesis ??

aneways the answer is 

According to th FAJAN rule the the higher the charge on the cation the higher is the polarising power and more the covalent character (as studied in class xi) so in pentahalides cation have a +5 charge and higher covalent character. 

Roma Patel , From Aditya Birla Public School , added an answer
Answered on 11/12/12
Higher the positive oxidation state of central atom, more will be its polarizing power which, in turn, increases the covalent character of bond formed between the central atom and the other atom.