Electronic Structure And Periodicity Flashcards
Electromagnetic spectrum
-Includes all forms of electromagnetic radiation (radiant energy)
~gamma rays, X rays, Ultraviolet, Visible light (ROYGBIV), Infrared, microwaves, radio waves
-characterized by frequency, wavelength, and amplitude
Gamma rays
-shortest wavelength
(10^-12 m)
-highest frequency
(10^20 Hz)
X rays
- wavelength = 10^-10 m
- frequency = 10^18 Hz
Ultraviolet
- wavelength = 10^-8 m
- frequency = 10^16 Hz
Visible light
Wavelengths: -Violet = 380nm (3.8x10^-7 m) -Indigo = 420nm -blue = 490nm -green = 520nm -yellow = 600nm -orange = 690nm -Red = 780nm (7.8x10^-7 m) Frequency = ~10^15 Hz (depending on color)
Infrared
- wavelength = 10^-6 m
- frequency = 10^14 Hz
Microwaves
- wavelength = 10^-3 m
- frequency = 10^10 Hz
Radio waves
- wavelength = 1 m
- frequency = 10^8 Hz
Frequency
- (v)
- the # of wave peaks that pass a given point, per unit time
- 1/s
Wavelength
- (lambda)
- the distance from 1 wave peak to the next
- m
Amplitude
- (A)
- the height of the wave (from center line to peak)
Frequency and wavelength relationship
- inversely related
- longer wavelength = lower frequency
- shorter wavelength = higher frequency
- Wavelength x Frequency = speed
- wavelength = speed/frequency
- frequency = speed/wavelength
- speed = the speed of light (2.998x10^8) unless otherwise specified
Diffraction and interference
- diffraction is the bedding of light around an object
- interference occurs when 2 or more waves superpose to form a new wave
- constructive = larger wave
- destructive = smaller or no wave
Photoelectric effect
-irritating a clean metal surface with light causes electrons to be ejected from the metal
Planck’s postulate
- a beam of light behaves as if it were a stream of small particles (photons)
- the energy of the photons is related to their frequency and wavelength
E = hv or E = hc/y
-h= Planck’s constant (6.626x10^-34)
-v = frequency
-c = speed of light (2.998x10^8)
-y = wavelength
-often asks for answer in per-mol basis, not per-photon (as answer gives), multiply per-photon energy by Avagadro’s number (6.02x10^23) to find per-mol energy
- higher frequency & shorter wavelength = higher E
- lower frequency & longer wavelength = lower E