Education.com is not a program, but does offer resources that can help your high school student with studying chemistry. I've linked those below.
I also suggest that you contact your child's school to learn if they offer any tutoring programs or chemistry clubs. If you don't have the school's contact information handy (and if located in the United States), you may research the school's phone number in SchoolFinder: http://www.education.com/schoolfinder
You might also ask the school or do some research online to learn if there are private tutors or programs for high school chemistry in your area.
My son's high school, a public school in northern California, is recommending Brigham Young University's online courses for students this summer. The link to their web site is below. I checked and they do offer Chemistry, under "Science - Chemistry". I'm not endorsing BYU, just passing along what was recommended to my son.