how is the name of the second one formed?
Carbon + hydrogen + oxygen (usually with a hydrogen–oxygen atom ratio of 2:1 as in water)
Carbohydrate
A carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where "m" may be different from "n"). 
what is metabolism? The set of life-sustaining chemical reactions in organisms. what are the key biochemicals? Amino acids, carbohydrates, nucleic acid and lipids
wiki:1583808
Carbohydrate [SEP] Introduction
A carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where "m" may be different from "n"). However, not all carbohydrates conform to this precise stoichiometric definition (e.g., uronic acids, deoxy-sugars such as fucose), nor are all chemicals that do conform to this definition automatically classified as carbohydrates (e.g. formaldehyde). The term is most common in biochemistry, where it is a synonym of saccharide, a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides.