Ch 7 - The Quantum-Mechanical Model of the Atom Flashcards
Quantum World
the absolutely small world of electrons behave differently tan out world(macroscopic) we behave in.
Things can be in two states at one time while unobserved.
Schrodingers Cat
1935 thought experiment designed to show how the ability for electrons to exists in two states does not transfer to the macroscopic world.
A cat can not be dead and undead at the same time. It is one or the other.
Quantum-Mechanical Model
a model that explains the strange behavior of electrons.
basis for certain chemical and physical properties of elements.
Wave-Particle Duality
light and electrons have certain properties that can either be thought of as a wave(rise and fall) or as a particle depending on the property.
Electromagnetic Radiation
Light is this.
A type of energy embodied in oscillating electric and magnetic fields.
Magnetic Field
a region of space where a magnetic particle experiences a force(think the space around a magnet)
Electric Field
a region of space where an electrically charged particle experience a force.
Example: a proton has an electric field around it.
Electromagnetic Radiation(detailed)
3.00 * 10^8 m/s(186,000mi/s)
Wave composed of oscillating, mutually perpendicular electric and magnetic fields propagating through space.
Amplitude
Wave characteristic.
the vertical height of a crest or depth of a trough.
Determines intensity or brightness.
Wavelength(weird A symbol)
the distance between adjacent crests(or any two analogous points) measured in units such as meters, micrometers, or nanometers.
Wavelength and Amplitude
related to the quantity of energy carried by a wave.
Can vary independently of each other.
Shorter lengths and higher wavers = more energy
Frequency(v)
the number of cycles(wave crests) that pass through a stationary point in a given period of time.
cycles/second(cycle/s or s^-1)
Hertz(Hz)
equivalent unit of frequency.
1 cycle/s
Frequency Formula
v = c/A(weird a symbol)
v = frequence
c = speed of light
A(weird A symbol) = wavelength
Visible Light
light that can be seen by the human eye.
wavelength determines color
Electromagnetic Spectrum
spectrum including all wavelengths of electromagnetic radiation.
Gamma Ray(weird Y symbol)
has the shortest wavelength and a very high energy level.
Produced by the sun, stars, and certain unstable atomic nuclei on Earth.
X-rays
2nd highest energy. Short wavelength. Pass through many substances that block visible light. great for mapping internal organs, bones, etc.
Can be harmful if exposed too often.
Ultraviolet(UV) Radiation
Longer wavelength than X-Rays. Produced most commonly by the sun. Can be harmful if overexposed(skin damage, cataracts)
Visible Light
ranging from violet(shorter wavelength, higher energy) to red(longer wavelength, lower energy).
Infrared(IR) Radiation
Longer wavelengths than visible light. Invisible to our eyes. Can be felt as heat. Used for nightvision technology.
Microwaves
Radar and microwave ovens. Longer wavelengths.
Radio Waves
Longest wavelengths. AM and FM radio, cell phones, tv, etc.
Interference
interaction between waves that either cancel or build each other up
Constructive Interference
“in phase”
waves that align with overlapping crest and creates a wave with twice the amplitude.
Destructive interference
“out of phase”
Waves that align so the crest from one wave overlaps with the trough of the other wave(opposites) and thus cancel each other
Diffraction
when a wave goes through an open slit it bends the wave.
Creates interference patterns(some spots where constructive and destructive interference happen)
Interference pattern
alternating pattern of constructive and destructive interference.
Often from diffraction.
Photoelectric Effect
the observation that many metals emit electrons when light shines upon them.
Showed the classical model did not explain how metals interact with light adequately.
Showed there were threshold frequencies and simply increasing the intensity of a light id not translate to the release of electrons
Einstein and the photoelectric effect
Proposed light energy must come in packets.
E = hv
E = energy h = Plancks constant(6.626*10^-34 J*S) v = frequency
Photon or Quantum
a packet of light
E = hv Energy = (plancks constant)(frequency)
or
because frequency = speed of light/wavelength
E = hc/wavelength(weird A symbol)
h = plancks constant c = 3.80*10^8m/s wavelength = typically given
Threshold Frequency Condition
based on Einsteins work:
the ability to dislodge electrons from a metal is based on whether or not a single photon has sufficient energy(hv) to dislodge a single electron.
hv = o with line through it(sounds like “fi”
if hv is = or greater than fi then it can dislodge an electron
kinetic energy and dislodging electrons
KE = hv - fi(the o with a line through it)
upon reaching the threshold frequency any extra energy in the photon is transferred to the electron as kinetic energy.
Wave Particle Duality of Light
sometimes light behaves like a particle and sometimes it haves like a wave.
Atomic Spectroscopy
the study of the electromagnetic radiation absorbed and emitted by atoms
Emission Spectrum
always the same for a particular element.
the seperation of light of a single element by sending it through a glass tube by passing it through a prism.
de Broglie ralation
wavelength(weird A) = h/mv
A = plancks constant/(mass)(velocity)
h = 6.626*10^-34
Complementary Properties
exclude each other.
Observing the wave nature of the electron excludes the particle nature and vice versa.
the act of observation forces one property to exists while the other is excluded.
Heisenbergs Uncertainty Principle
(deltaX)(mdeltaV) greater than or equal to (h/4pie)
deltaX = uncertainty of position
deltaV = uncertainty of velocity
m = mass of particle
h - plancks constant(6.626*10^-34)
**the more accurately you know the position of an electron the less accurately you know the velocity and vice versa
deterministic
the present determines the future.
Part of classic physics that the quantum mechanical model disrupts.
Indeterminancy
the present does not determine the future. only a statistical representation of the event will give a likely outcome but no guarantee.
Probability Distribution Map
a statistical map that shows where an electron is likely to be found under a given set of conditions.
Orbital
a probability distribution map showing where the electron is likely to be found around the nucleus.
Wave function
a mathematical function that describes the wavelike nature of the electron
