Final answer:
Hydrogen atoms emit a pink color when an electric current is passed through a tube containing hydrogen gas. This color results from the combination of four distinct lines in the atomic emission spectrum of hydrogen. The spectrum contains specific wavelengths corresponding to electron transitions between energy levels within the hydrogen atoms.
Step-by-step explanation:
When an electric current is passed through a tube containing hydrogen, hydrogen atoms absorb some of the electrical energy and reemit it as a pink color. This phenomenon is associated with the atomic emission spectrum of hydrogen, which consists of photons of four visible wavelengths that result in an overall pink light when combined. However, when this emitted pink light is passed through a prism, it is spread out into its component frequencies, revealing a line spectrum. The hydrogen spectrum's characteristic lines correspond to specific transitions between the energy levels of its electrons. The most intense red line at 656 nm is due to the transition from the third to the second energy level. Hydrogen atoms become excited when they absorb energy from an electric discharge, which raises their electrons to higher energy levels. When these electrons descend back to lower energy states, they emit light of specific wavelengths. The pink color observed is the result of the combined effect of the four discrete emission lines in the visible range associated with these electron transitions. Each of these emission lines represents a single wavelength of light, indicating the light emitted by the gas is composed of a set of discrete energies.