Final answer:
Atomic spectra, unique to each element, consist of discrete lines that represent electron transitions between energy levels in atoms. Emission spectra occur when electrons fall to lower energy levels, while absorption spectra show where light is absorbed by electrons moving to higher states.
Step-by-step explanation:
Atomic spectra are a critical tool in modern science, providing fundamental knowledge about the atomic structure through the analysis of light emitted or absorbed by atoms. The true statement about atomic spectra is that they are unique to each element and consist of lines corresponding to discrete energies involved in electron transitions between different energy levels within an atom. This understanding emerged from Niels Bohr's work, who posited that electrons inhabit distinct energy levels, and transitions between these levels result in the emission or absorption of light at specific wavelengths.
When electrons in an atom become excited, they move to higher energy levels. Upon returning to their ground state, an emission spectrum is produced, identifiable as bright lines at particular wavelengths. Conversely, an absorption spectrum forms when electrons absorb energy and transition to higher energy levels, resulting in characteristic dark lines in the spectrum where light at certain wavelengths has been absorbed.
The complexity of these spectral lines, revealed through high-resolution measurements, has provided rich details on the structure of the atom and the behavior of electrons in their orbits. This has been instrumental in fields such as astronomy, where spectroscopy is used to determine the composition of celestial objects, and in various other applications, like forensic analysis, where identifying substance composition is essential.
The spectral lines are not only signatures of the elements themselves but also of the physical conditions within the star or gas cloud being observed. Thus, through the study of atomic spectra, scientists can infer not just the presence of elements but also environmental conditions like temperature and pressure.