Related Clues:

• N preceders?
• Itsy-bitsy bit
• Small wonder?
• 1950s filmstrip, "Our Friend, the ___"
• Fermi's tidbit
• Fermi's particle
• Very little bit
• Tiny source of energy
• It gets smashed
• Subject for Bohr
• Lepton site
• It's smaller than a molecule
• Bit of matter
• With 41-Down, nuclear device
• Bit to be split