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Ionic v Covalent Bond

Posted: Sun Oct 27, 2019 4:55 pm
by Rohan Kubba Dis 4B
I understand that there are not truly any definite values that dictate whether a bond is covalent or ionic. However, in the book it says that a good rule of thumb is that an electronegativity difference of two means that the bond has so much ionic character, it is best regarded as ionic. Are there any more values that implicate either covalent or ionic like this?

Re: Ionic v Covalent Bond

Posted: Sun Oct 27, 2019 5:02 pm
by JustinHorriat_4f
basically every atom has an electronegativity, which is how much an atom attracts electrons. Therefore the reason it says if the electronegativity difference is more than 2 consider it ionic is because at that point the electrons are not being shared anymore and instead one atom takes the electron while the other gives it up. Less than 2 it means that the two atoms electronegativity is similar enough for the bond to be covalent.

Re: Ionic v Covalent Bond

Posted: Sun Oct 27, 2019 6:02 pm
by Eesha Sohail 1D
In addition to the above, generally a difference in electronegativity between 0 and 0.5 will be regarded as a nonpolar bond, while a difference between 0.5 and 2.0 will be seen as polar, hence why it is seen more as a sliding scale than a set distinction.

Re: Ionic v Covalent Bond

Posted: Sun Oct 27, 2019 8:09 pm
by DHavo_1E
Rohan Kubba Dis 4B wrote:I understand that there are not truly any definite values that dictate whether a bond is covalent or ionic. However, in the book it says that a good rule of thumb is that an electronegativity difference of two means that the bond has so much ionic character, it is best regarded as ionic. Are there any more values that implicate either covalent or ionic like this?


Hi,
Ionic bonds also happen between metals and nonmetals, while covalent bonds happen between nonmetals.
In addition, ionic bonds happen due to a large difference in electronegativity (a value greater than two as you've mentioned), so much so that the electrons are actually ripped away from the metal by the nonmetal. Additionally, if the electronegative value is less than 0.5, it is nonpolar covalent which is when electrons are shared equally because the electronegativity of both atoms are relatively equal and if it is between 0.5 and 1.6, is it a polar covalent, meaning the electrons are unequally shared as one atom is more electronegative than the other, having increased electron density around the more electronegative atom.