Chemistry 110

Chemistry 110 - Chemistry 110 Chapter 2: Charles Augustin...

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Chemistry 110 Chapter 2: Charles Augustin de Coulomb - Coulomb’s law: charged bodies Inverse square law : force depends on the square of distance -force on body 1 by body 2 (charges q1 and q2) F=q1q2/r^2 - Opposite charges : q1q2<0 (opposites attract) - Like charges : q1q2>0 (likes attract) -Electromagnetic force “rules” in chemistry repulsion + attraction Proton: mass= -1.673*10^-27kg charge= +1.602*10^-19C Electron: mass= 9.109*10^-31kg charge= -1.602*10^-19C Element- identical atoms Atomic Number - number of protons Isotope - same number of protons, different number of neutrons Positive Ion- Cation Negative Ion- Anion E= chemical symbol Z= atomic number, proton number A= mass number, protons + neutrons A-Z= neutron number AMU= atomic mass unit -proton= 1.0073 AMU -neutron= 1.0087 AMU -electron= 0.00055 AMU ± = charge Rutherford + Geiger- study the inner structure of atoms -Nuclear atom: Gold-foil experiment James Chadwick- neutrons Rutherford- protons 1) most mass and all positive charge are located in the nucleus and the remainder of the atom is empty space 2) the positive charge is one-half the atomic weight of an element 3) if there are as many electrons on the outside as there are protons in the nucleus, the atom is neutral Chemical Symbols- abbreviations of elements -elements beyond U-92 do not occur naturally Isotopes - atoms with the same atomic number but different mass numbers Percent Natural Abundances - percent that certain isotopes occur in nature. Ions - ions are formed when atoms lose or gain electrons -the number of protons does not change when an atom becomes an ion Mass Spectrometer - a beam of ions separates elements into components of differing masses Atomic Mass (weight)- the average of the elements isotopic masses, weighted according to the abundance of naturally occurring isotopes of the element
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Mole - the amount of a substance that has the same number of elementary entities as atoms in 12g of Carbon 12 Avogadro Constant - Nsub(a)- the “number of elementary entities” in a mole Nsub(a)= 6.02214199*10^23mol^-1 Molar Mass (M)- the mass of one mole of atoms -Avogadro’s number is not suitable to count everyday materials but is excellent for counting atoms and molecules Calculating using the mole concept: -always try to get a proper cancellation of units -think in terms of the expected result Essential Formulas: Quadratic formula: -b ±√ (b^2-4ac)/2a V=at d=1/2at^2 f=ma f=mg f=q1q2/r^2 Chapter 8: Balmer Equation: E=hv - Planck’s constant -> h=6.62607*10^-34Js E= Quanta- packets of energy Blackbody - absorbs and emits all radiation regardless of frequency Rayleigh + Jeans - predicted infinite density P=8 π kT/ λ ^4 p=energy density k=Boltemann’s constant T=absolute temperature Photoelectric Effect- -light shined on metals->electrons ejected from the metal surface -electron emission only at the threshold frequency KE=1/2meu^2=hv-hv0=hv- Φ KE=1/2mv^2 J=Kgm^2s^-2 eV=1.602*10^-19J (single e-) Science- Theory + Experiment -experiment is the ultimate arbiter
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This note was uploaded on 12/25/2011 for the course CHEM 110 taught by Professor Fenster during the Fall '07 term at McGill.

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Chemistry 110 - Chemistry 110 Chapter 2: Charles Augustin...

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