<em>Answer: </em>John Dalton
Explanation: Democritus was a Greek philosopher (470-380 B.C.) who is the father of modern atomic thought. He proposed that matter could NOT be divided into smaller pieces forever. John Dalton created the very first atomic theory.
Uses for radioactive tracers is to look for flaws in metal objects and are also used by doctors to x-ray images to look at your bones.
Barium nitride
copy the name of the metal as it is written in the periodic table and the first part of the name of the nonmetal (nitrogen) and replace the end by "ide"
