Your best bet is to register for another section or to email Chemistry Undergraduate Services to ask if a wait-list has been started (note: this is different than a BearTracks watch-list, which can only notify you if spaces open but cannot tell you if there are other people on a wait-list).
The section sizes are physically limited by the number of workstations available in the laboratories, which means that we cannot arbitrarily add more students to a section.
Bear Tracks web registration closes early because lab classes may begin before the official Term Registration Deadline (see the current U of A calendar) has passed. As stated on Bear Tracks and the official Class Schedule, after web registration has closed, you should email registration inquiries to undergrad@chem.ualberta.ca.
Your lab room will be assigned after Bear Tracks registration closes. Please see eClass for more details.