Possible Clues:

• L, M, N & T make up one part of the whole
• Perhaps copper's energy allowed men to be captured
• That may be currently glowing for the chemist
• One's preferred environment
• Gold, e.g.
• Mercury, e.g.
• Fundamental part of whole
• One in the table LMN - T
• Currently it glows in a chemical manner
• Electric device with terminals