The starting material in a chemical reaction is called ___? and ___ materials made by humans, not naturally?

Answer 1

reactant(s)
Synthetic

Answer 2

Starting material = Reagent or the reactant.
---materials? = The usual answer is "man-made." For example, rayon is called a man-made fiber, cotton is called a natural fiber, whereas nylon is called a synthetic fiber. This is because rayon is made by humans from cellulose, which may be from cotton waste or wood. This cellulose is dissolved in a mix of sodium hydroxide and carbon disulfide to form xanthate. Then that xanthate is squirted into an acid solution to produce rayon (cellulose) fibers. So the fiber existed before as cellulose. It's just that people dissolved the cellulose, then re-precipitated it. But in the politically correct era, some persons object to the term "man-made."