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electromagnetic radiation: light; radiant energy that has wavelike behavior and travels at the speed of light in a vacuume.g. light from sun, microwave, X rays, radiant heat from fireplace waves have three primary characteristicswavelength (λ, lambda): distance between two consecutive peaks or troughs in a wavefrequency (ν, nu): number of waves (cycles) per second that pass a given point in spaceshortest wavelength has highest frequencylongest wavelength has lowest frequencyspeed
λ: wavelength (m)ν: frequency (cycles/s)c: speed of light (2.9979 × 10⁸ m/s)hertz (Hz): 1 cycle per second (1/s)cycles are implied
initial definitions of matter and energyend of 19th century: matter and energy were distinctmatter: particleshad massposition in space could be specifiedenergy: wavesmasslessdelocalized; position in space could not be specifiedbeginning of 20th centuryGerman Max Planck: studied radiation profiles emitted by solid bodies heated to incandescenceresults could not be explained in terms of the present physics (that matter could absorb or emit any quantity of energy)Planck’s constant: 
energy can be gained or lost only in whole-number multiples of hνchange in energy for a system: 
n: integerh: Planck’s constantν: frequency fo electromagnetic radiation absorbed or emittedquantization: energy transfer can only occur in discrete quanta (packets)photon: quantum of electromagnetic radiation
h: Planck’s constantν: frequency of radiationλ: wavelength of radiation
photoelectric effect: electrons emitted from the surface of a metal when light strikes itno electrons are emitted by a given metal below a specific threshold frequency (ν₀)for light with frequency lower than the threshold frequency, no electrons are emitted regardless of the intensity of the lightfor light with frequency greater than the threshold frequency, the number of electrons emitted increases with the intensity of the lightfor light with frequency greater than the threshold frequency, the kinetic energy of the emitted electrons increases linearly with the frequency of the lightexplanationassume:electromagnetic radiation is quantized (consists of photons)threshold frequency represents the minimum energy required to remove the electron from the metal’s surface
m: mass of electronv: velocity of electronhν: energy of incident protonhν₀: energy required to remove electron from metal’s surfaceintensity of light is a measure of the number of protons present in a given part of the beam, so a greater intensity means that more photons are available to release electrons (as long as ν > ν₀)Einstein’s special theory of relativity: 
m: massc: speed of lightenergy has mass
can calculate mass associated with given quantity of energy calculate apparent mass of photonenergy of each photon: 
duel nature of light: electromagnetic radiation exhibits wave properties and certain characteristics of particulate matter as welldoes particulate matter exhibit wave properties?mass and wavelength particle with velocity
de Broglie’s equation
allows you to calculate wavelength for a particlediffraction: light scattered from a regular array of points or linesdifferent colors resultvarious wavelengths of visible light are not all scattered in the same waycolors “separated” like light passing through a prismdiffraction pattern: caused by scattered radiation; bright spots and dark patternscan only be explained in terms of waves, so proves that matter obeys de Broglie’s equationall matter exhibits both particulate and wave properties
a sample of hydrogen gas receives a high-energy spark → H₂ molecules absorb energy → some H—H bonds are broken → excited hydrogen atomscontain excess energy that is released by emitting light of various wavelengths to produce emission spectrumcontinuous spectrum: contains all the wavelengths of visible lightwhen light passes through a prismline spectrum: a few lines of lighteach line corresponds to a discrete wavelengthonly certain energies are allowed for the electron in the atom (quantized)
quantum model: electrons move around the nucleus only in certain allowed circular orbitsenergy levels available to electron in hydrogen atom
n: integer (larger value → larger orbit radius)Z: nuclear chargenegative: energy of electron bound to nucleus is lower than if at infinite distance, where there is no interaction and energy is 0
ground state: lowest possible energy statetwo important points about Bohr modelmodel correctly fits quantized energy levels of hydrogen atom and postulates only certain allowed circular orbits for the electronas the electron becomes more tightly bound, its energy becomes more negative relative to the zero-energy reference state (infinite distance from the nucleus). As the electron is brought closer to the nucleus, energy is released from the system
does not work when applied to atoms other than hydrogen; electrons do not move around the nucleus in circular orbits
standing wave: stationary; waves do not travelwave or quantum mechanics: electron in hydrogen atom imagined to be standing wave
ψ: wave functionfunction of the coordinates (x, y, z) of the electron’s position in three-dimensional spaceĤ: operatorset of mathematical intsructionsproduces total energy of the atom when the mathematical terms are applied to the wave functionE: total energy of the atompotential energy due to attraction between proton and electronkinetic energy of moving electronorbital: specific wave function, characterized by a particular value of Equantum (wave) mechanical modeldo not know the pathway of the orbitalsHeisenberg uncertainty principle: there is a fundamental limitation to just how precisely we can know both the position and momentum of a particle at a given time
Δx: uncertainty in a particle’s positionΔ(mv): uncertainty in a particle’s momentumh: Planck’s constantmore accurately we know a particle’s position, the less accurately we can know its momentum and vice versa
the square of the function indicates the probability of finding an electron near a particular point in spacee.g. relative probability of finding electron at positions 1 and 2substitute x, y, z for the two positions, square function value, compute ratio
N₁/N₂: ratio of probabilities of finding the electrons at positions 1 and 2probability distribution: intensity of color used to indicate probability value near a given point in spacea.k.a. electron density mapelectron density and electron probability mean the same thingradial probability distribution: plots total probability of finding the electron in each spherical shell versus the distance from the nucleusmaximum occurs because:probability of finding an electron at particular position greatest near nucleusvolume of spherical shell increases with distance from the nucleuswhen moving away from the nucleus, probability decreases but summing more positionsdescribing size of hydrogen 1s orbital: radius of the sphere that encloses 90% of the total electron probabilityorbital is a wave function, but most helpful to picture as three-dimensional electron density map
quantum numbers: describe various properties of the orbitalprincipal quantum number (n): integral valuesrelated to size and energy of orbitalas n increases:orbital becomes larger
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7. Atomic structure and periodicity
Electromagnetic radiation
Nature of matter
Photoelectric effect
Atomic spectrum of hydrogen
Bohr model
Quantum mechanical model of atom
Physical meaning of a wave function
Quantum numbers
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