Emission Spectrum (Simplified): Study with Video Lessons, Practice Problems & Examples

Emission spectra are created when light emitted from an atom passes through a slit and prism, revealing discrete lines corresponding to various wavelengths. As electrons transition from higher energy levels to their ground state, they emit energy in the form of light. This process allows for the calculation of wavelengths, energy, and frequency of emitted light, which are essential for understanding atomic structure and behavior. The emission spectrum serves as a valuable tool in identifying elements and their properties, linking energy transitions to observable spectral lines.

Emission Spectrum (Simplified) Concept 1

Now, emission spectra is a series of lines formed when emitted light is focused by a slit and passes through a prism. So remember, we have our atom here, and here we have our first shell. And theoretically, there's an infinite number of shells within a given atom. We haven't found all the elements in the universe, so there are elements out there that we still don't know about. So the number of shells is infinite. And we're going to say here we have an electron that's at a higher energy state and a higher energy level. And what's going to happen is eventually it starts to come back down to its ground state. So it's dropping back down to the first shell. Remember, as an electron drops back down from a higher shell to a lower shell, it emits energy. This energy is emitted as light. What happens here is the slit will focus this energy, and what happens there is it passes through a prism. This prism allows us to split that energy into its various wavelengths and create this emission spectrum. So remember, a slit is just a narrow long narrow cut used to spread closely packed wavelengths which can later be measured. So we can examine this emission spectrum and we can measure the wavelengths of each one of these colored lines. Just realize here that the prism itself, it helps transform these wavelengths into discrete lines on the emission spectra. So all that's really going on here is we're focusing the emitted energy as an electron drops from a higher shell number down to a lower shell number and imposing them on an emission spectrum. From there, we can calculate their wavelengths, and in that way also calculate the energy and or frequency of these different wavelengths of light.

Emission Spectrum (Simplified) Example 1

The lines in an atomic emission spectrum are due to the presence of isotopes. Well, when we talked about the emission spectrum that's created, we never mentioned isotopes. Movement of electrons from higher energy states to lower energy states in atoms. We did say this. We said that as the electron falls from a higher energy level or shell number to a lower one, it emits energy in the form of light. The slit focuses this energy through a prism in order to superimpose it on an emission spectrum. So this is true. Here, nuclear transitions in atoms, which we never discussed, and then this is saying the opposite. It's saying we're going from a lower energy state to a higher energy state. This would require absorption of energy, so the slit wouldn't be able to focus any emitted energy to create our emission spectrum. So, this is the opposite of what is needed. So here, option b would be the best answer, and remember the name is emission spectrum. So remember what emission is. We're going from a higher energy state or shell number to a lower one. That should have been a key indicator that option b was the best answer.

The emission spectrum of helium is shown below. Which emission spectrum line has the highest energy?

• A. Line A
• B. Line B
• C. Line C
• D. Line D
• E. Line E

Here’s what students ask on this topic:

What is an emission spectrum and how is it formed?

An emission spectrum is a series of lines formed when light emitted from an atom passes through a slit and a prism. This process reveals discrete lines corresponding to various wavelengths. When an electron in an atom transitions from a higher energy level to its ground state, it emits energy in the form of light. This emitted light is focused by a slit and then passed through a prism, which splits the light into its component wavelengths. These wavelengths appear as distinct lines on the emission spectrum, allowing us to measure and calculate the energy and frequency of the emitted light.

How do electrons produce light in an emission spectrum?

Electrons produce light in an emission spectrum by transitioning from a higher energy level to a lower energy level within an atom. When an electron drops from a higher shell to a lower shell, it releases energy in the form of light. This emitted light is then focused by a slit and passed through a prism, which separates the light into its various wavelengths. These wavelengths appear as distinct lines on the emission spectrum, corresponding to the specific energy transitions of the electrons.

What role does a prism play in creating an emission spectrum?

A prism plays a crucial role in creating an emission spectrum by separating the emitted light into its component wavelengths. When light emitted from an atom passes through a slit, it is focused into a narrow beam. This beam then passes through a prism, which disperses the light into its various wavelengths. The prism allows us to see the discrete lines of the emission spectrum, each corresponding to a specific wavelength of light. This separation of wavelengths helps in identifying the energy transitions of electrons within the atom.

How can the emission spectrum be used to identify elements?

The emission spectrum can be used to identify elements because each element has a unique set of energy levels and, therefore, a unique emission spectrum. When electrons in an atom transition between energy levels, they emit light at specific wavelengths. By analyzing the distinct lines in the emission spectrum, we can determine the wavelengths of the emitted light and match them to known values for different elements. This allows us to identify the element based on its characteristic emission spectrum.

What is the relationship between wavelength, energy, and frequency in an emission spectrum?

The relationship between wavelength, energy, and frequency in an emission spectrum is governed by the equations: $c=\lambda \nu$ and $E=h\nu$, where $c$ is the speed of light, $\lambda$ is the wavelength, $\nu$ is the frequency, $E$ is the energy, and $h$ is Planck's constant. As the wavelength decreases, the frequency and energy increase, and vice versa. This relationship helps in calculating the energy and frequency of the emitted light from its wavelength.