Question

why covalent bond not formed when electronegativity diffrence is greater than zero?


only correct answer

Answer 1

f E.N difference is greater than 1.7 the compound is said to be ionic. In covalent bonding, the E.N difference is less than 1.7. Covalent bond formation does not necessarily need same sized atoms.

Answer 2

Answer:

The first thing to consider is the difference between covalent and ionic bonding, from the UCDavis ChemWiki site Ionic and Covalent Bonds,

In ionic bonding, atoms transfer electrons to each other. Ionic bonds require at least one electron donor and one electron acceptor. In contrast, atoms that have the same electronegativity share electrons in covalent bonds since donating or receiving electrons is unfavorable.

The electron donor has a low electronegativity and the electron acceptor has a higher elelctronegativity - so there is a difference in electronegativity ΔEN, effectively creating a positive and negative end