I recently found a table of electronegativity differences, where certain differences where used to define certain types of bonds. However I found different values at different sites so I wonder if someone could help sort this out. Link 1 http://www.files.chem.vt.edu/RVGS/ACT/notes/electronegativity This is the values I used for comparing the bonds witihin the molecules but had to stop when I found new ones. Also found another one saying an electronnegativity difference of less than 0.4 (instead of 0.5) is nonpolar covalent bonds... Link 2 http://www.mikeblaber.org/oldwine/chm1045/notes/Bonding/Polarity/Bond05.htm This one is the most wierdet making huge value differences compared to what I have found more. Link 3 http://www.chemteam.info/Bonding/Electroneg-Bond-Polarity.html This one brought up new unmentioned "rules" However further research with this just didnt make any sense. Sodium sulfide, lets take the sulfide ion, they say that the S-O bond is COVALENT, HOW? The electronneg. diff. gives you 3.5-2.5=1 which is LARGER than 0.4(or 0.5 who ever is correct). How can this be a NONPOLAR covalent bond, I am just confused... What is the correct values for electronnegativity? Thanks in advance Regards, Robin Andersson.