CHEM 101L-EXP.8 QUESTIONS AND ANSWERS
Describe the electronic processes associated with absorption or emission of
radiation. Which process is associated with an electron moving to a higher
energy level?
- gain energy by absorbing light to jump to another level.
- When it wants to go back to its natural state it releases a photon
- Emission = Higher to lower
- Absorption = Lower to higher
How the energy level of an electron related to the energy of a photon?
They are limited by orbitals.They need a specific amount of energy to jump form one
orbital to the next.
Describe the Balmer series and how to recognize it through experimental
observations.
The visible spectrum of light from hydrogen displays four wavelengths, 410 nm (n=3),
434 nm (n=4), 486 nm (n=5), and 656 nm (n=6), that correspond to emissions of
photons by electrons in excited states transitioning to the quantum level described by
the principal quantum number n=2.
- There are also a number of ultraviolet Balmer lines with wavelengths shorter than 400
nm.
How are the terms in the Rydberg equation defined? How can they be used to
determine the starting and/or ending energy levels of an electronic transition?
- For hydrogen nf=2 and then you can solve for ni
- Rh = 2.18x 10^-18 J
How does the spectroscope convert the light from a particular source into a
spectrum, set of bright lines, or both? Why do different light sources produce
different spectra?
- diffraction device used to see the different types of wavelengths transmitted
- Inside there is a transmission diffraction grating (piece of glass or plastic with fine
scratches or grooves cut in its surface)
- each groove scatters light but only light waves scattered in specific directions from the
grooves on the grating interfere constructively, producing a strong beam
- Different light sources produce different spectra because each light source comes
from a different origin ( continuous- temp dependent vs emission or discrete- substance
dependent)
How does the Hydrogen lamp produce light? How is this relevant to the purpose
of this experiment?
- Electrical discharge tube-glass tube that contains metal electrodes at each end and is
filled with a low-pressure gas, such as hydrogen, helium, or mercury.
- A stream of fast moving electrons shoots through the gas from the cathode.
- These electrons get excited to a new energy level and then return to their ground state
resulting in the emission of light.
What color is the Hydrogen lamp to the naked eye? What appears when observed
through a spectroscope?
Describe the electronic processes associated with absorption or emission of
radiation. Which process is associated with an electron moving to a higher
energy level?
- gain energy by absorbing light to jump to another level.
- When it wants to go back to its natural state it releases a photon
- Emission = Higher to lower
- Absorption = Lower to higher
How the energy level of an electron related to the energy of a photon?
They are limited by orbitals.They need a specific amount of energy to jump form one
orbital to the next.
Describe the Balmer series and how to recognize it through experimental
observations.
The visible spectrum of light from hydrogen displays four wavelengths, 410 nm (n=3),
434 nm (n=4), 486 nm (n=5), and 656 nm (n=6), that correspond to emissions of
photons by electrons in excited states transitioning to the quantum level described by
the principal quantum number n=2.
- There are also a number of ultraviolet Balmer lines with wavelengths shorter than 400
nm.
How are the terms in the Rydberg equation defined? How can they be used to
determine the starting and/or ending energy levels of an electronic transition?
- For hydrogen nf=2 and then you can solve for ni
- Rh = 2.18x 10^-18 J
How does the spectroscope convert the light from a particular source into a
spectrum, set of bright lines, or both? Why do different light sources produce
different spectra?
- diffraction device used to see the different types of wavelengths transmitted
- Inside there is a transmission diffraction grating (piece of glass or plastic with fine
scratches or grooves cut in its surface)
- each groove scatters light but only light waves scattered in specific directions from the
grooves on the grating interfere constructively, producing a strong beam
- Different light sources produce different spectra because each light source comes
from a different origin ( continuous- temp dependent vs emission or discrete- substance
dependent)
How does the Hydrogen lamp produce light? How is this relevant to the purpose
of this experiment?
- Electrical discharge tube-glass tube that contains metal electrodes at each end and is
filled with a low-pressure gas, such as hydrogen, helium, or mercury.
- A stream of fast moving electrons shoots through the gas from the cathode.
- These electrons get excited to a new energy level and then return to their ground state
resulting in the emission of light.
What color is the Hydrogen lamp to the naked eye? What appears when observed
through a spectroscope?
