How do you calculate the difference of electronegatives fir a compound?

Question

aaronq · Answer

Subtract the smaller value from the larger value.

anonymous · Answer

How do I find the values themselves?

aaronq · Answer

they would be on a periodic table, like this one http://ptable.com

anonymous · Answer

What if it's not an element on the periodic table such as (sulfur trioxide)?

aaronq · Answer

that's not an element, it's a molecule made from 2 elements. When you compare electronegativities, you're comparing 2 atoms across a bond.|dw:1381674421424:dw|
you can find the difference between A and B or B and C, but not A and C because they don't form a bond.     $\chi_E^{AB}$=|E1-E2| and   $\chi_E^{BC}$=|E2-E3|

aaronq · Answer

first draw the molecule in a lewis dot diagram, so you know what elements are in it.