Isotope, in chemistry, one of two or more forms of an element that have the same atomic number but different atomic weights.
One person lay in critical condition on Feb. 29, 2008, after the deadly biotoxin ricin was found in his Las Vegas hotel room. What is ricin, and why is it so dangerous?
Pianos lose their tuning, guitars fall out of key -- even church organs need to be tuned every now and then. For centuries, the only sure-fire way to tell if an instrument was in tune was to use a tuning fork.