S.1.3.1 and S.1.3.2 Emission Spectra Flashcards
Continuous spectrum
Contains light of all wavelengths and all frequencies
Line spectrum
Contains selected frequencies; gaps in the spectrum
Spectrometry
Light interacting with matter
Light
All waves on the electromagnetic spectrum (waves of energy)
What does adding energy to electrons do?
Allows electrons to overcome the electrostatic attractive forces and move to the next shell
Attractive forces keep electrons as close to the nucleus as possible
Emission spectrum
A hot gas is placed in front of a prism and produces a line spectrum on a black background
Absorption spectrum
A cold gas is placed between a prism and a light source and produces a line spectrum with gaps on the background of a continuous spectrum
Electromagnetic radiation
Emitted in different forms of differing energies; travels at the speed of light; can be distinguished by different wavelengths
Frequency
Number of waves that pass a particular point in a second
Relationship between frequency and wavelength
Inversely proportional
Electron in the excited state
Unstable, immediately returns to ground state by giving out energy in the form of electromagnetic radiation
Photon
Packet of energy released for each electron transition between energy levels
IMPORTANT!
No answer needed
Gases produce a characteristic emission line spectrum when heated to a high temperature
Energy of photon
Proportional to the frequency of the radiation
E = hf
Quantization
The idea that electromagnetic radiation comes in discrete packets (quanta)
IMPORTANT!
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Electrons will absorb and release only the exact energy required to move between allowable energy states
Energy is quantized
An electron moving between two energy levels always absorbs and releases the same, discrete amount of energy
What is the evidence for quantization?
Line (not continuous) spectra for each element
Evidence for the structure of the atom
- Atoms emit photons of certain (not continuous) energies; these energies correspond to certain frequencies, telling us the electrons are located on energy levels
- Energy is quantized (line spectra)
Convergence
Shells converge at higher frequencies (farther away from the nucleus)
What happens as shells converge?
They form a continuum wherein no extra energy is needed for the electrons to move between shells (ionized atom)
UV released
Any higher shell to the ground state
Visible light released
Any higher shell to the second shell
Infrared waves released
Any higher shell to a shell n > 2
IMPORTANT!
No answer needed
Electrons do not always immediately return to the ground state after being excited once and may move to a higher shell if given more energy
