Major: Chemical Engineering
Run-of-the-mill chemists develop new compounds and determine the structures and properties of things that already exist. You knew that. Chemical Engineering is different from and more complicated than chemistry because it emphasizes the commercial applications of chemical reactions; it involves harnessing chemical reactions to produce things people want. It's a very broad field that overlaps considerably with other branches of engineering, chemistry, and biochemistry.
If you major in Chemical Engineering, you'll learn how to reorganize the structure of molecules and how to design chemical processes through which chemicals, petroleum, foods, and pharmaceuticals can undergo. You'll learn how to build and operate industrial plants where raw materials are chemically altered. You'll learn how to keep the environment safe from potential pollution and hazardous waste, too.
Chemical Engineering is not an easy major (at all), but if you can make it through to graduation day, you'll be in demand. Paper mills, manufacturers of fertilizers, pharmaceutical companies, plastics makers, and tons of other kinds of firms will be looking for just your expertise, and they'll pay you pretty handsomely for it. You should also know that, traditionally, more Chemical Engineering majors obtain master's and doctoral degrees than students in almost any other engineering field, and that this major makes for a wonderful stepping stone to both law and medicine.