ChemistryWiki | RecentChanges | Preferences
- Chemical Bonding or sharing of electrons with two atoms do not require that the shared electrons be located equally between the two atoms.
- In fact most often these electrons are located closer to one of two atoms.
- The more electronegative element has more desire for the electron thereby the shared electrons are located closer to this atom.
- Therefore, there is an uneven distribution of electron thereby making one end of the bond have more electrons (partially negative) and the other end have less electrons (partially positive).
A general rule of thumb for predicting the type of bond based upon electronegativity differences:
- If the differences in electronegativities (delta EN) is less than 0.80, the bond is non-polar covalent
- If the difference in electronegativities (delta EN) is greater than or equal to 0.80, the bond is polar covalent
- If the difference in electronegativities (delta EN) greater or equal to 1.7, the bond is ionic
- In real life, there are no hard and fast cut-offs (i.e. greater than 1.7, ionic), it is a gradual change. You would need to know additional chemical concepts to be certain. Therefore, this is why we use the above cut-offs in 1st year cheimstry.