chapter 21 Atomic Physics

What is blackbody radiation?

electromagnetic waves reflected off a blackbody

What is a blackbody?

object that has absorbed almost all electromagnetic wave

What is an example of a blackbody?

black hole

What is ultraviolet catastrophe?

failed prediction of classical physics that the energy radiated by a blackbody at extremely short wavelengths is extremely large and that the total energy radiated is infinite; occurs in end of UV spectrum

What is the photoelectric effect?

emission of electrons from a material when light of certain frequencies shines on the surface of the material

photon

unit or quantum of light; a particle of electromagnetic radiation that has zero rest mass and carries a quantum of energy

work function

minimum energy needed to remove an electron from a metal atom

emission spectrum

increase in the wavelength of a photon emitted relative to the photon absorbed when scattered by individual electrons or nucleons

absorption spectrum

diagram or graph that indicates the wavelengths of radiant energy that a substance absorbs

uncertainty principal

principle that states that determining both the position and the velocity of an electron or any other particle simultaneously is impossible

red light

lower frequency, fatter wavelength

violet light

higher frequency, shorter wavelength

What is the reasoning behind ultraviolet radiation?

Max Planck said that this is because light is quantized

What did ultraviolet catastrophe experiments show?

Experiments showed that as the wavelength decreased, the energy decreased also

What is quantized energy?

submicroscopic electric oscillators called resonators could only absorb and give off certain amounts of energy

What does quantized mean?

bundles of energy (photons)

Explain the Uncertainty Principle.

to view an electron's location you would have to use light to see it. The light striking the electron would increase its energy, therefore changing its momentum

What is the electron cloud?

area in which you can predict that you can there will be an electron in there

Their energy is quantized

What does the fact that an emission spectrum contains only certain wavelengths show about electrons?

energy levels

the quantized features found inside an atom

absorption spectrum

the set of wavelengths absorbed by a gas

Plank

Who discovered that electrons are quantized?

the center of an atom's nucleus is positive

What did Rutherford discover?

Hydrogen atom and that electrons have different energy levels

What did Bohr discover?