Phosphorus has an atomic number of 15 and an atomic weight of 30.974. From this information it can be determined that this element Naim 23:57 Small Molecules and the Chemistry of Life Phosphorus has an atomic number of 15 and an atomic weight of 30.974. From this information it can be determined that this element a. has isotopes. b. forms isomers. c. has a pH of 7. d. is an ion. e. is radioactive. Answer: A Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+