Answer: Carbon is the only element that can form so many different compounds because each carbon atom can form four chemical bonds to other atoms, and because the carbon atom is just the right, small size to fit in comfortably as parts of very large molecules.
Explanation: Carbon's characteristics include its ability to bond with oxygen, hydrogen, nitrogen, phosphorus and sulfur. Carbon biochemical compounds are essential to all life on the planet. Carbon atoms can bond to one another and form different structures. Which is not a function of proteins.