Electrons are allowed "in between" quantized energy levels, and, thus, only specific lines are observed. The energies of atoms are not quantized. The energies of atoms are quantized. Electrons are not allowed "in between" quantized energy levels, and, thus, only specific lines are observed. When an electron moves from one energy level to another during absorption, a specific wavelength of light (with specific energy) is emitted. When an electron moves from one energy level to another during emission, a specific wavelength of light (with specific energy) is emitted.