Carbohydrates are a class of macromolecules that provides our bodies with energy. Carbohydrates are polymers that consist of long chains of simple sugars. Monosaccharides (aka simple sugars) are the basic building block of carbohydrates.
Monosaccharides (simple sugars) are the building blocks of all carbohydrates. The general sugar structure of a carbohydrate is (CH2O)n; hence, this is where the term carbohydrate was derived (carbo - carbon and hydrate - from water). The 'n' refers to the number of carbons that compose the carbohydrate.
How can two molecules have the same exact molecular formula? Pretend two students in a biology class were given the following combination of Legos: 4 red Legos, 3 blue Legos, 2 green Legos and 1 yellow Lego. Each student was told to build something with those Legos.