The Periodic Table of the Elements

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The Periodic Table of the Elements
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Matter is made of Atoms

• tiny nucleus (protons neutrons) surrounded by
  cloud of electrons, in stable shells/ orbits
• charges protons e electrons -e neutrons 0
• proton gt the element (atomic number Z)
• universe is almost all (gt99) hydrogen 1H (1p,
  0n) and helium 4He (2p, 2n)
• chemistry electron clouds combine into stable
  molecules H2O, CH4, CO2, SiO2 . . .
• electrons can jump from orbit to orbit,
  releasing or absorbing energy as photons gt Bohr
  atom

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Fig.07.01

• The abundance of elements in the solar system
• Overwhelmingly H2 and He, due to Sun!!

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Fig.07.02
The Maxwellian distribution of speeds

• in the atmospheres of planets (pretty fast!!
• there are lots of collisions between molecules
• lighter molecules move faster (H2 is lightest)
• if typical speeds are greater than 1/6 escape
  velocity planet loses that gas

N2
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Weight of gas above is balanced by pressure below
Result atmospheres (and all heavenly bodies)
have higher pressures at lower depths
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Phases of Matter

• Solid (common in planets, also interstellar dust)
• elemental, dense iron (Fe)
• mineral, floats on metal quartz SiO2, basalt
  Fe2SiO4

• Liquid (less common in planets)
• elemental mercury (Hg), bromine (Br)
• molecular water H2O, ammonia NH3, methane CH4

• Gas very common in planets, also interstellar
• H2, He, N2, O2

• Plasma VERY common
• tear off one, two or all electrons gt charged
  nucleus Ze which retains property of element
  from nuclear physics view, but chemistry is
  wrecked
• naked protons, electrons (solar wind)

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Temperature and Light

• All surfaces emit/absorb EM radiation
• Depends on temperature T and surface
• Black-Body perfect emitter/absorber
• E energy radiated per unit time per unit area
  power per unit area intensity (bad symbol)
• Total energy varies strongly with temperature
  (s 5.67 x 10-8 W/K4-m2)
  Stephan-Boltzmann law E s T4
• Spectral peak varies inversely with T Wiens
  law Tlmax 2.9 x 106 nm-K

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Fig.07.06
BlackBody EM radiation

• peak shifts toward lower wavelength as T
  increases Wiens law
• more energy per area per time emitted at all
  wavelengths as T increases
• red-hot is about

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Color Temperature F K

• Faint Red 930 770
• Blood Red 1075 855
• Dark Cherry 1175 910
• Medium Cherry 1275 965
• Cherry 1375 1020
• Bright Cherry 1450 1060
• Orangish 1940 1350
• Yellow-White 10,000 6000

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BlackBody temperatures if the planet were black

• Earth is warmer because of atmosphere
  (greenhouse effect)
• Venus is a LOT warmer because of its very dense
  atmosphere

TYPO!!
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Temperature and Light

• Equipartition Theorem Typical energy of atom
  or photon is E kT where k Boltzmanns
  constant 8.6 x 10-5 eV/K
• Wiens law lmaxT 2.9x10-3 m- K gt peak
  wavelength varies inversely with T
• Range of T from a few degrees (outer space) gt
  mm mwave to 10,000º or more gt 100 or less nm
  visible into UV for hottest stars
• Einstein Equipartition E hf hc/l kTgt
  lT hc/k lT (4.1x10-15 eV-s)(3x108
  m/s)/(8.6x10-5 eV/K)
• .0143 m-K 14.3x10-3 m-K (in the
  park!!)
• Molecular speeds from equipartition, m
  molecules mass

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Some Reference Temperatures part II C are 300
lower F are twice as big

• T (K) kT (eV) lmax
  comment
• 3 .25 meV 1 mm mwave
  night sky temp
• 300 1/40 10,000 nm far IR FIR
  room temp
• 500 .04 For 1H, v 3.5 km/s
  Sn melts
• 1200 .1 2400 nm IR Ag
  melts red
• 1800 .15 1600 nm NIR Fe melts,
  Bi boils orange-yellow
• 3000 .2 1000 nm NIR W melts
  Fe boils yellow
• 6000 .4 500 nm vis W boils
  suns temp yellow-white
• 50,000 5 58 nm UV flame plasma
  temp blue-white

Note that kT, the average energy, is about 1/5
the energy of the peak position as given by the
Wien law and Einstein photon