At top, 7-year-old John Curl watches a demonstration with his mom, Jaimi Butler, during "Having a Ball With Chemistry" on Saturday. The American Chemical Society hosted the event for children at the Salt Lake City Public Library to celebrate National Chemistry Week and to get kids interested in science. Above, Grace Michaels, 8, left, Natalie Michaels, 7, and John watch as a rose is dipped in liquid nitrogen to freeze it during a chemistry demonstration.