Sugars are the best-known carbohydrates. The simplest are monosaccharides , and have four to six carbons and form in a ring. Their sweetness is related to the ring structure. They can also be chained to form starches or cellulose. The two are identical except for the way the sugars are attached.
Carbohydrates often contain oxygen, which is a polar or charged atom.
It adds a charge to the sugar molecule, so it dissolves easily in water. The idea of molecular charge is going to be important as we go through the organic compounds. Lipids or fats are non-polar molecules. That means they have few charged portions, so do not attract water. In fact, they repel water so that when fats are placed in water, they form into a ball.