Why is the atomic emission spectrum of hydrogen composed of lines? What does each line indicate? Why do the lines become closer together from left to right in a typical diagram?
The hydrogen atom with its one electron in the N=1 shell is in it's "ground" state. When it absorbs a photon of energy of just the right amount, the electron is promoted to a higher energy level such as N = 2, N = 3, N = 4, etc. This "excited" atom stays in that state a nanosecond or so before the electron falls to a lower energy level. When that happens the atom emits a photon of energy equal to the difference between the starting and ending energy levels. Each transition from a higher level to a lower level results in a "line" of a particular wavelength when viewed with a device that separates the wavelengths such as a spectroscope, spectrograph or spectrophotometer. The lines are closer together toward shorter wavelengths because the energy levels are closer together as they progress from N = 1 to N = infinity.
The atomic emission spectrum of hydrogen is composed of lines due to the quantized energy levels of the electrons in a hydrogen atom. Each line indicates a specific transition of an electron between different energy levels in the atom.
To understand why the lines are present in the spectrum, we need to discuss the electronic structure of hydrogen. The hydrogen atom consists of a nucleus (a single proton) and an electron orbiting around it. According to quantum mechanics, the electron can only occupy certain energy levels, which are quantized. When the electron absorbs energy, it moves to a higher energy level known as an excited state. However, this excited state is not stable, and the electron tends to return to its original lower energy level or ground state. When the electron moves back to a lower energy level, it releases the excess energy in the form of photons.
Each line in the spectrum corresponds to a specific transition between energy levels. The line's position is determined by the energy difference between the initial and final energy levels. The energy of a photon is directly proportional to its frequency, and hence, the wavelength of the emitted light is inversely proportional to its energy. Therefore, each line in the spectrum represents a specific wavelength or color of light.
Now, let's discuss why the lines in the hydrogen spectrum become closer together from left to right in a typical diagram. The lines in the spectrum are labeled using the Balmer series, where each line is assigned an integer value, starting from 3. The lines with higher numbers have shorter wavelengths and higher energies. As the line number increases, the energy difference between adjacent energy levels decreases, and thus, the wavelengths become closer together.
This phenomenon is a consequence of the quantized energy levels in the hydrogen atom. The energy levels of an atom are governed by the behavior of the electron and are determined by the equation for the energy levels in hydrogen called the Rydberg formula. This formula shows that the energy difference between energy levels decreases as you move towards higher energy levels, resulting in the observed pattern of the lines getting closer together in the spectrum.
In summary, the atomic emission spectrum of hydrogen is composed of lines due to transitions of the electron between energy levels. Each line represents a specific wavelength or color of light, indicating the energy difference between the initial and final energy levels. The lines become closer together from left to right in a typical diagram because the energy differences between energy levels decrease as the line number increases.