Possible Clues:

• Dating material
• Mince pies, too, with sulphur, providing atomic elements
• Stoops, i.e. to become odd types of atoms
• Springfield's minor-league team on 'The Simpsons'
• Springfield minor leaguers
• Poet is so confused about forms of chemical elements
• Uranium has many
• Elemental relatives
• Deuterium and tritium, to hydrogen
• Chemist's relatives?