What did alchemists contribute to the development of chemistry?

The alchemists were the first chemists, but they were also mixing chemicals, they believed that magic would help with their experiments.but it didn't. but their experiments of the science of chemistry did.

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.