Emission Spectrum (Simplified): Videos & Practice Problems

Emission spectra are created when light emitted from an atom passes through a slit and prism, revealing discrete lines corresponding to different wavelengths. As electrons transition from higher energy shells to lower ones, they emit energy in the form of light. This process allows for the measurement of wavelengths, which can be used to calculate energy and frequency. Understanding these concepts is crucial for grasping atomic structure and the behavior of light in relation to energy levels and electron transitions.

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 to 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 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

Answer: (A)

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 is focused by a slit and passes through a prism. This process reveals discrete lines corresponding to different wavelengths. When an electron in an atom transitions from a higher energy shell to a lower one, it emits energy in the form of light. This emitted light is then focused by a slit and passed through a prism, which splits the light into its various wavelengths, creating the emission spectrum. Each line in the spectrum represents a specific wavelength of light, which can be measured to calculate the energy and frequency of the emitted light.

How do electron transitions relate to the emission spectrum?

Electron transitions are directly related to the emission spectrum. When an electron in an atom moves from a higher energy shell to a lower energy shell, it releases energy in the form of light. This emitted light corresponds to specific wavelengths, which are observed as lines in the emission spectrum. The position and intensity of these lines depend on the energy difference between the initial and final energy levels of the electron. By analyzing the emission spectrum, we can determine the energy levels within the atom and understand the behavior of electrons during these transitions.

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

A prism plays a crucial role in creating an emission spectrum by splitting the emitted light into its various 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 component wavelengths. The prism separates the light based on the different wavelengths, creating discrete lines on the emission spectrum. These lines represent the specific wavelengths of light emitted during electron transitions, allowing us to measure and analyze the energy and frequency of the emitted light.

How can the wavelengths in an emission spectrum be measured?

The wavelengths in an emission spectrum can be measured using a spectrometer. A spectrometer is an instrument that disperses light into its component wavelengths and measures the intensity of each wavelength. When light emitted from an atom passes through a slit and prism, it creates an emission spectrum with discrete lines. The spectrometer captures this spectrum and records the position and intensity of each line. By analyzing the recorded data, we can determine the specific wavelengths of the emitted light. These measurements can then be used to calculate the energy and frequency of the light, providing valuable information about the atomic structure and electron transitions.

Why is understanding emission spectra important in studying atomic structure?

Understanding emission spectra is important in studying atomic structure because it provides insights into the energy levels and behavior of electrons within an atom. The emission spectrum reveals the specific wavelengths of light emitted during electron transitions, which correspond to the energy differences between different energy levels. By analyzing these wavelengths, we can determine the energy levels within the atom and understand how electrons move between these levels. This information is crucial for understanding the atomic structure, the behavior of electrons, and the interactions between light and matter. It also has practical applications in fields such as spectroscopy, quantum mechanics, and astrophysics.