It is not impossible in a theoretical sense, but a small chemistry department may offer some courses only once every two years may make it difficult to arrange courses so that required courses can all be taken in the non-study-abroad semesters.
Without knowing the college the OP’s student is enrolled in, it is difficult for anyone else to determine whether the major requirements can be scheduled around a study-abroad semester. Note that doing so may require starting in first or second year taking a non-usual course sequence in some cases.