Perfect chemistry, by Simone Elkeles

Gang member Alex and head cheerleader Brittany are assigned as partners in Chemistry lab, and their personal chemistry sets off a chain reaction that has life changing effects. In less skilled hands, the plot could be ordinary, but Elkeles writes well, and the romantic story becomes one that's impossible to put down as together the two struggle to become the adults they want to be instead of following the paths others expect of them. The secondary characters are interesting as well, from Alex's tough widowed mother, Brittany's handicapped older sister, and their Chemistry teacher, who cares passionately about her students while knowing the difference between being supportive and trying to be a friend to her students.