Atomic Structure Flashcards
electromagnetic radiation
light: form of energy that is produced by the movement of electrically charged particles through space
wavelength
λ the distance between two given points on neighboring wave cycles (SI unit: meter)
Frequency
v: number of waves that pass through a given point in a given amount of time; called hertz (Hz) in cycles or oscillations per second
Hertz
measure of frequency
Amplitude
A: maximum height of the wave (SI unit: meter)
c=
c=λv
c- speed at which the wave travels
wavelength and frequency are — proportional
inversely
speed of light
2.998e10^8 m/s
Order of visible light spectrum
gamma rays, (-16) x rays, UV, visible light, IR, microwave, FM, AM, long radio waves (8)
photons
massless particles that are packets of energy
Rayleigh-Jeans Law
demonstrate the relationship of spectral radiance to be inversely proportional to the wavelength of light from a black body at a given temperature.
Planck’s Law
limit on how energy is emitted at different wavelengths, particularly at short wavelengths (high frequencies)
nergy could not be emitted continuously as classical physics suggested, rather, energy had to be emitted in discrete packets called quanta
Planck’s Constant formula and value
E=hv=(hc/λ)
h=6.626e-34
photoelectric effect
emission of electrons from a material cause electromagnetic radiation.
Threshold frequency
Light at low frequency (below the threshold frequency for a given material) did not eject any electrons. However, if the frequency of light was increased enough (past the threshold frequency), electrons were ejected immediately without a time delay. The more intense the light, the more electrons were ejected
A frequency at or beyond the threshold frequency resulted in an ejection of electrons. Increasing light intensity at or beyond the threshold frequency resulted in more electrons being ejected.
Kinetic Energy of an electron
T_electron = E_photon - work function (Φ)
If the photon did not have enough energy to eject an electron
the energy of the photon is either (1) reflected, (2) absorbed by the material leading to a small increase in thermal energy, or (3) scattered.
wave-particle duality
light exhibits both wave-like and particle-like properties
line emission spectrum
Atoms of a particular element in the gas phase, when exposed to high voltage, emit specific, intense wavelengths of light (specific colors if in the visible region) where each wavelength of light corresponds to a specific amount of energy emitted.
spectral lines are unique to the element
Bohr Model
electrons transfer between levels which takes a set amount of energy released in the form of light
ΔE electronic transition
E_final- E_initial
simplifies to
-R_y ( (1/n^2_final) - (1/n^2 initial) )
free electron relationship between mass (m) and velocity (v) and wavelength
λ=h/mv
wavelength decreases with increasing mass
Standing waves
stationary waves that oscillate with time with a peak amplitude profile that does not move through space
Node
point where amplitude is always zero and waves do not move at all
