
 Home Common Compounds Exam Guide FAQ Features Glossary Construction Kits Companion Notes Just Ask Antoine! Simulations Slide Index Toolbox Tutorial Index
FAQ
Introduction Measurement Matter Atoms & ions Compounds Chemical change The mole Gases Energy & change The quantum theory Electrons in atoms The periodic table
Solids Liquids Solutions Acids & bases Redox reactions Reaction rates Organic chemistry Everyday chemistry Inorganic chemistry Environmental chemistry Laboratory History of chemistry Miscellaneous
|  |
Why are OH, NH, and FH bonds so polar?
- Why is the partial charge on a hydrogen atom bonded to a highly electronegative element more concentrated than for any other element?
mjn@1-2000.com
-
Hydrogen atoms are very small (with an atomic radius of about 37 pm, they're smaller than any other atom but helium).
So when a bonded electronegative atom pulls electrons away from the hydrogen atom, the positive
charge that results is tightly concentrated. The small size of the hydrogen atom is one factor responsible for the unusual strength of the
dipole-dipole interaction we call "hydrogen bonding".
When gauging the strength of intermolecular attractions, considering the magnitude of partial charges isn't enough; you also must look at how spread out the charges are. The atomic radius trends you've learned are often very helpful here.
Author: Fred Senese senese@antoine.frostburg.edu |