To search for information about summer research programs funded by the National Science Foundation, try visiting NSF's REU web site. They are typically very slow in posting information about upcoming programs; however, you can often get a list of sites (and links) where programs occurred in the previous summer. Many of the same schools will also be running programs in the coming summer.
Some universities operate summer programs that are not government supported. You might begin a search of the internet by hunting for REU (Research Experiences for Undergraduates) programs in chemistry or biochemistry (or related fields). Try also titles like SURF (Summer Undergraduate Research Fellowship), SURP (Summer Undergraduate Research Program), SROP (Summer Research Opportunities Program), etc.
Be careful that you don't miss deadlines. Many deadlines for submission of applications occur between late January and early March, and announcements of programs may be issued at the last minute.
Summer programs typically last eight to ten weeks. Most programs pay a stipend. Many programs furnish (or pay for) room and board. Some pay for transportation. Some offer academic credit. Some will pay for you to present your work at a scientific meeting.
A few programs are interested only in students who will have finished the junior year. Many programs will consider students after the sophomore year if organic chemistry has been completed. Programs supported by the NSF are normally open only to U.S. residents.
Biochemistry majors ought to look at programs in the Biological Sciences as well as those in Chemistry.
"Premed" students ought not to dismiss the idea of a summer spent on research. It is certainly possible that you can find a program that involves both science and medicine. And you should remember that research experiences can help to set one apart when professional schools consider your credentials.