Chapter 07: The Quantum-Mechanical Model of the Atom Flashcards
Light
A form of electromagnetic radiation
Composed of perpendicular oscillating waves
(one = electric field, other = magnetic field)
Electric field
A region where an electrically charged particle experiences a force
Magnetic field
A region where a magnetized perticle experiences a force
Speed of light
c
c = 3.00 × 108 m/s
Wavelength
λ (lambda)
The distance between identical points on successive waves
*Inversely proportional to frequency
Amplitude
The verticle distance from the midline of a wave to the peak (or trough)
A measure of light intensity
*Directly proportional to total energy of wave
(larger amplitude = more force)
Frequency
- v* (nu)
- v* = c / λ
The number of waves that pass through a particular point in a given period of time
hertz (Hz) or cycles per second (1 s-1)
1 Hz = 1 s-1
*Directly proportional to total energy of a wave
(More frequency = more total force)
*Inversely proportional to wavelenth
Electromagnetic spectrum
Low energy to high:
radio
microwave
infared
visible light
ultraviolet
X-ray
gamma ray
Interference
The interaction between waves
Constructive interference
Occurs when waves that are in phase interact so that they add to make a larger wave
*Amplitudes are summed making the larger wave
Destructive interference
Occurs when waves that are out of phase interact so that they cancel each other out (flat line)
Diffraction
Occurs when a traveling wave encounters an obstacle or opening in a barrier that is about the same size as its wavelengh and it bends (diffracts) around it
*Waves diffract
**Particles DO NOT diffract (they just pass through opening)
Interference pattern
Inherent characteristic of all waves
Light is diffracted through two slits creating an alternating pattern
Photoelectric effect
The observation that many metals emit electrons when light shines on their surface
Quanta or photons
Light energy delivered to atoms in “packets”
Photon energy
E
E = hv
v = c/λ
Thus:
E = hc/λ
Planck’s constant
h
h = 6.626 × 10-34 J×s
Threshold frequency
Reached when the energy of a photon is equal to the binding energy of emitted electron
hv = Φ
or E = Φ