why the bond energy of kcl is more than nacl?"?

Answer 1

Yes. Since both potassium and sodium are from the same group - Group I of the Periodic Table, they have similar properties, except that reactivity increases down the group, therefore potassium has a greater reactivity than sodium. This also means that the bond energy increases as well.

Answer 2

If you read this webpage: http://www.chemguide.co.uk/inorganic/group1/properties.html , you will see that Li, Na, K, Rb and Cs all are from the same group, all with 1 electron in its outermost shell. Because the heavier elements have more electron rings, their last electrons are much farther from their cores, and thus they have lower integrity and can easily bond with another element. KCl has a stronger bond than NaCl because K is a bigger atom, and its last electron is farther away from its core than Na's last electron.

Answer 3

if you see the electronic configuration of potassium & chlorine you 'll see dat both have same no. of electrons when they are covalently bonded 2 form KCl.this the reason why they are close enough 2 eachother &a huge amount of energy is required 2 break such bond & hence they have higher bondenergy. while in case of sodium & chlorine there is difference in no. of electrons & also in bonding which is ionic in NaCl. hence less amount of energy is required 2 break such bond.