Related Clues:

• Variant element form
• Compound sharing a formula but having its own atomic arrangement
• Distinct form of an element
• One of two compounds differing in arrangement of the same atoms
• Element in certain form – very first to fill in that is
• Looking back, it's about most unfinished chemistry at the centre of a couple of compounds
• Atom with same atomic number but different number of neutrons
• More is needed to synthesise an atomic nucleus
• Oo, spite! (anag.)
• Atomic requirement that's protecting drunk before work
• Atomic nucleus; is more (anag.)
• Atomic nucleus with a different energy state to other nuclei
• One's love to exercise is a small part of energy process
• A few locked in centre of firm's compound
• Poise to analyse physicist's concern