Why does each chemical element have its own line spectra, and why all atoms of one chemical element emit light with the same line spectrum?
The difference in the sets of possible energy states of atoms of different chemical elements leads to a difference in their line spectra. Atoms of the same chemical element have the same set of energy states.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.