Because an egg is an entire biological structure, made up of a mixture of chemicals rather than a single pure chemical compound, there is no one chemical formula to describe it. However, the basic structure and chemistry of an egg is highly conserved and varies little from species to species.
The egg itself has three main parts: the shell, the egg white and the egg yolk. The shell is composed primarily of calcium phosphate salts, which is similar in composition to human bone. The egg white is made of water, osmotic regulatory salts and a serum protein called albumin. The yolk, which serves as a source of food for a growing bird embryo, is made of many types of high-energy lipids.