Jmol Molecular Models: Water, Hydronium Hydroxide, and Ethane

Here is a model of two water molecules. The oxygen atoms have a stronger hold on the bonding electrons than the hydrogen atoms do. As a result, the oxygen atoms have a net negative charge and are colored red (black in the black-and-white paperback). The hydrogen atoms have a net positive charge and are colored white. Such a postively-charged hydrogen atom is often called a proton. We refer to such molecules (with positive and negative regions) as polar.

If one water molecule passes a proton to another water molecule, the receiver becomes a hydronium ion and the passer becomes a hydroxide ion.

Ethane is shown to the same scale for comparison. Red-and-white (polar) molecules attract one another more strongly than green-and-tan non-polar molecules. As a result, polar and ionic substances tend to be soluble in one another, but not in non-polar substances. We say “like dissolves like.”