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Level 151

Identifying Atoms by their Spectra; the Doppler Sh

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Absolute Zero
0 Kelvin, no movement of particles
an object that is an ideal radiator when hot and a perfect absorber when cool. It absorbs all radiation that falls upon it, reflecting no light; hence it appears black. Stars are approximately blackbodies.…
A temperature scale with the lowest possible temperature at the zero point, which is called absolute zero.
the amount of energy radiated per second by a body. Ex: the wattage of a lightbulb defines its luminosity. Stellar luminosity is usually measured in units of the Sun's luminosity (approx: 4x 1026 watts
Stefan-Boltzmann constant
constant that appears in the laws of thermal radiation
Stefan-Boltzmann law
the amount of energy radiated by one square meter in one second by a hot, dense material depends on the temperature T raised to the fourth power
thermal energy
a hot coffee mug
thermal radiation
the continuous spectrum of electromagnetic radiation emitted as a result of the thermal energy in any relatively dense material
Wien's Law
a relation between a body's temperature and the wavelength at which it emits radiation most intensely. Hotter bodies radiate more intensely at shorter wavelengths. mathematically...
absorption-line spectrum
a spectrum in which certain wavelengths are darker than adjacent wavelengths. The missing light is absorbed by atoms or molecules between the source and the observer
Balmer lines
a series of absorption or emission lines of hydrogen seen at visible wavelengths
Bohr model
… can jump between orbits only if it absorbs or emits the exact energy difference between the orbitals
continuous spectrum
a spectrum with neither dark absorption nor bright emission lines. The intensity of the radiation in such a spectrum changes smoothly from one wavelength to the next
emission-line spectrum
a spectrum consisting of bright lines at certain wavelengths separated by darker regions in which little or no radiation is emitted
energy level
any of the numerous levels that an electron can occupy in an atom, roughly corresponding to an electron orbital
ionization energy
The energy required for the complete removal of 1 mol of electrons from 1 mol of gaseous atoms or ions
Kirchoff's laws
3 rules that describe how continuous, bright line, and dark line spectra are produced
the study and analysis of spectra
Any decrease in wavelength (increase in frequency)
Doppler shift
change in apparent frequency
Doppler broadening
the widening of a spectral line caused by motions of the material producing the line both toward and away from the observer
radial velocity
the velocity of a body along one's line of sight. that is the part of a body's motion directly toward or away from the observer
Red Shift
a shift in the wavelength of electromagnetic radiation to a longer wavelength. For visible light, this implies a shift toward the red end of the spectrum. The shift can be caused by a sourc…