Question

Which substance has the greatest ionic character?
A. $C{l_2}O$
B. $NC{l_3}$
C. $PbC{l_2}$
D. $BaC{l_2}$

Answer 1

Hint:We know ionic character is the amount of electron sharing between two atoms. Ionic bond is formed when there is an electronegativity difference between the two species. Example sodium chloride $NaCl$ in this case chlorine is more electronegative in nature and hence it accepts the electron pair donated by the sodium ion. More is the electronegativity difference more ionic character. We can also take an example of $CsF$ which has the highest ionic character.

Complete step-by-step answer:We know that all the elements present in the periodic table form bonds. Now the bond can be of many types as we have the ionic bond which is formed between two elements of electronegativity difference so that one element will donate its electron pair and the other will accept it. While in case of covalent bonds there is a sharing phenomenon of electrons in the compound. There is polarity in bond due to electronegativity difference but bond will remain as such by sharing.
Among the following options we have to choose an option where there is maximum difference in electronegativity, we can also say that the one element should be of alkali metal group while the other can be halogen. So, now as according to the options we have $BaC{l_2}$ in which barium has the capability to donate electrons while chlorine has more electronegativity and it will accept the electrons forming a very strong ionic bond. We can also relate it according to Fajan’s rule, “a compound with low positive charge, small anion and large cation has ionic bond whereas a compound with high positive charge, small cation and large anion has a covalent bond.”

So, covalent character is inversely proportional to the size of cation and covalent character is directly proportional to size of anion. Lower the covalent character, higher will be the ionic character. Except $BaC{l_2}$ other have covalent character decreases from left to right
$NC{l_3} > \,C{l_2}O > \,PbC{l_2} > \,BaC{l_2}$
As you see that $BaC{l_2}$ have the least covalent character hence, from the above discussion we clearly say that $BaC{l_2}$ has the greatest ionic character among these. It has the greatest ionic character, due to greater electronegativity difference between cation and anion and large size of cation.

Hence option (D) is the correct answer.

Note:Ionic properties or Ionic character can be determined by comparing electronegativity differences between atoms in a molecule. The greater the difference - the greater the ionic character. Due to the high ionic strength ionic Compounds have high boiling and melting points they require a lot of energy to break. Ionic compounds form crystals that are brittle and break into small pieces easily.