For the lithium gas the indigo line has a wavelength of
The correct answer and explanation is:
The indigo line for lithium gas corresponds to a specific wavelength, typically around 445.4 nm. This wavelength is part of the visible spectrum, specifically in the blue-indigo range, and is observed when lithium atoms in a gaseous state undergo an electron transition from a higher energy level to a lower one.
In atomic physics, when energy is supplied to a gas like lithium, its atoms absorb energy and the electrons are excited to higher energy levels. When these electrons return to their lower energy states, they release the energy in the form of light. The wavelength of this emitted light depends on the energy difference between the two levels involved in the transition.
The specific wavelengths of emitted light from an atom form a spectrum, and each element has its own unique set of spectral lines. For lithium, the indigo line arises from a transition within the lithium atom’s energy levels. The precise value of 445.4 nm falls within the blue to indigo section of the visible spectrum, which ranges from approximately 400 nm to 450 nm. This is one of several prominent spectral lines of lithium, with others appearing at different wavelengths such as red (670.8 nm) and violet (320 nm).
The appearance of these spectral lines is a result of the quantized nature of energy levels in atoms. Each element has a unique electronic structure, which explains why different elements emit light at distinct wavelengths when energized. The lithium spectral lines have been studied extensively, and they serve as important benchmarks in spectroscopy, aiding in the analysis of atomic and molecular structures.