Don't worry; it can be a bit confusing at first, but I'll try to clarify things for you!
Emission and absorption spectra are related to the behavior of atoms and molecules when interacting with light. Let's break it down:
- Emission Spectrum: When atoms or molecules are excited (usually by heat or energy), electrons can move to higher energy levels. As these excited electrons return to their lower energy levels, they release the excess energy in the form of light. The emitted light consists of specific wavelengths that are characteristic of the element or molecule.
In an emission spectrum, the black lines (or dark lines) represent the wavelengths of light that are absorbed by the atoms or molecules in a sample. These dark lines correspond to the specific energies required to excite the electrons to higher energy levels. When the electrons drop back to lower energy levels, they emit light at those same wavelengths, resulting in bright lines in the spectrum.
- Absorption Spectrum: An absorption spectrum is the opposite of an emission spectrum. Instead of excited electrons emitting light, the sample of atoms or molecules absorbs certain wavelengths of light when it is exposed to a continuous spectrum of light (like white light). The absorbed wavelengths correspond to the specific energies needed to excite the electrons. The absorbed wavelengths appear as dark lines (absence of light) in the absorption spectrum.
Now, to answer your second question: No, the wavelengths emitted are not the same as those absorbed. They are complementary processes. The wavelengths that are absorbed (dark lines in the absorption spectrum) are the same as those emitted (bright lines in the emission spectrum) when the excited electrons return to lower energy levels.
To summarize, emission and absorption spectra show the wavelengths of light that are either emitted or absorbed by atoms and molecules. The emitted wavelengths are specific to the element or molecule, and the absorbed wavelengths correspond to the energies required to excite the electrons to higher energy levels. The emitted wavelengths are the same as the absorbed wavelengths because they represent the same electronic transitions happening in reverse.