Question #d8bb7

1 Answer
Nov 11, 2016

See explanation.


The reason why water is a polar molecule is because of the electronegativity difference between hydrogen and oxygen. Electronegativity is a fancy word for how much an atom wants electrons. The higher the electronegativity, the more an atom will pull in an electron.

Oxygen has a much higher electronegativity than hydrogen, so oxygen pulls in the electrons more. As a result, more electrons are around the oxygen atom, and oxygen has a partial negative charge. That means the electrons spend less time orbiting around the hydrogen atom - instead, they're hanging out with oxygen - so hydrogen has a partial positive charge.

The #"Na"^+"# ions are positive, indicated by the + sign. Positive attracts negative, so the #"Na"^+"# ions will be attracted to negatively charged ions. We just established that oxygen has a negative charge, so the #"Na"^+"# ions will be attracted to oxygen. So, the #"Na"^+"# should go in the boxes that are surrounded by oxygen:
enter image source here

The #"Cl"^-"# ions, on the other hand, have a negative charge, so the positive ends of the water molecules will be attracted to them. The positive ends, as I explained above, are the hydrogen atoms, which have partial positive charges. So the #"Cl"^-"# ions should be surrounded by hydrogen ions:
enter image source here