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Atomic Structure & Electron Configuration

Atomic Structure & Electron Configuration. Ch.3. (3-1) Atomic Theory. All matter is composed of indivisible particles called atoms Certain characteristics shared by all chemical cmpds. Law of Definite Proportions. Any sample of a cmpd always has the same composition (by mass)

yoshio-beasley
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Atomic Structure & Electron Configuration

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  1. Atomic Structure & Electron Configuration Ch.3

  2. (3-1) Atomic Theory • All matter is composed of indivisible particles called atoms • Certain characteristics shared by all chemical cmpds

  3. Law of Definite Proportions • Any sample of a cmpd always has the same composition (by mass) • Ex: NaCl always 39% Na & 61% Cl

  4. Law of Conservation of Mass • Product mass = reactant mass • Ex: S + O2 SO2 sulfur oxygen sulfur dioxide 32.07 amu 32.00 amu 64.07 amu

  5. Law of Multiple Proportions • Mass ratio for combining 1 element w/ another are expressed in small whole #’s • Ex: NO2 NO N2O

  6. Dalton’s Atomic Theory • Matter is made of indivisible & indestructible atoms • Atoms of a given element are identical in their properties • Atoms of different elements differ in their properties

  7. Dalton’s Atomic Theory • Atoms of different elements combine in simple whole-# ratios to form cmpds • Chemical rxns consist of the combination, separation, or rearrangement of atoms.

  8. Modifications to Dalton’s Theory • 2 principles no longer valid • subatomic particles • overlooked atoms combining w/ their own type

  9. Atomic Mass • p+ + n0 (e- mass negligible) • Units: atomic mass units (amu) • Exactly 1/12 the mass of 1 carbon-12 atom

  10. Atomic Mass to Kg • 1 amu = 1.66 x 10-27 kg • Mass of copper atom: 63.546 amu x 1.66 x 10-27 kg = 1.06 x 10-25 kg 1 amu

  11. Mole • (mol): amt of substance • Avogadro’s constant: 6.02 x 1023 particles 1 mol • 1 g/mol = 1 amu

  12. Mass & Moles • Mass of 1 mol of Fluorine atoms: 18.9984 amu x 1.66 x 10-27 kg x 1000 g 1 amu 1 kg x 6.02 x 1023 = 18.9984 g/mol 1 mol

  13. (3-2) Subatomic Particles • Smaller particles that make up an atom • 3 types

  14. Electrodes • Anode: where e- enter a metal; + charge • Cathode: where e- leave a metal; -charge

  15. Cathode Ray Tube Experiment • J.J. Thomson • e- had mass • e- had negative charge

  16. Nucleus • Central region of an atom containing p+ & n0 • Plum-pudding model: Thomson • e- embedded in positively charged ball of matter

  17. Gold Foil Experiment • Ernest Rutherford • Alpha particles: + charged particles • dense nucleus w/ lots of empty space around it

  18. Atomic Number • # of p+ in the nucleus of an atom • Mass #: total # of p+ & n0 in the nucleus • 42He: mass # = 4, atomic # = 2 • 2 p+, 2 n0, 2 e-

  19. Coulomb’s Law • The closer 2 charges come together, the greater the force b/w them • Opposites attract, likes repel • Strong force: greater than repulsive force at close distance • p+ in nucleus

  20. Isotopes • Atoms of the same element w/ different #’s of n0 • Ex: Helium-3 (1n, 2p), Helium-4 (2n, 2p) • Radioisotope: unstable atom that undergoes radioactive decay

  21. (3-3) Electromagnetic Spectrum • Total range of electromagnetic radiation • e- have properties of both particles & waves

  22. Wavelength • λ: distance b/w 2 consecutive peaks or troughs • m

  23. Frequency • v : # of waves that pass a stationary pt. in 1 sec. • Hz

  24. Speed of Light • c = 3.0 x 108 m/s • Speed of light = freq. x wavelength c = v λ • Ex: v = _c_ = 3.0 x 108 m/s λ 7.6 x 10-7 m = 3.9 x 1014 /s = 3.9 x 1014 Hz

  25. Line-emission Spectrum • Distinct lines of colored light produced by excited atoms of an element passing through a prism

  26. Quantum Theory • Tells exact E of the e-, but only the probability that the e- is in a particular region • Quantized

  27. Quantum #’s • Principal (n): 1-7, E level e- is located • Shape: sublevel w/in E level • Orientation: orbital w/in sublevel • Spin: +1/2, -1/2

  28. Bohr’s Atomic Model • Describes e- in terms of their E states • Ground state: lowest E state • Excited state: higher E state than ground

  29. Orbitals • Regions of space where you can expect to find e- of specific E • s (sphere), p (dumb-bell), d, f

  30. Pauli Exclusion Principle • No more than 2 e- can occupy a single orbital & must have different spins

  31. s d s p f Electron Configuration • Description of occupied e- orbitals in an atom • s (1 orbital), p (3), d (5), f (7) • F: 1s22s22p5 • Main E level, orbital, # of e-

  32. Orbital Diagrams • Similar to e- config. but lines designate orbitals and arrows designate e- • __ __ __ __ __ 1s 2s 2p http://www.colorado.edu/physics/2000/applets/a2.html

  33. Aufbau Principle • Lowest & most stable E levels filled first • 4s before 3d

  34. Hund’s Rule • Orbitals are occupied by 1 e- before any pairing occurs

  35. Noble Gas Configuration • Electron Config.: S: 1s22s22p63s23p4 • Noble Gas Config.: S: [Ne]3s23p4 • Unless specified do not use noble gas configuration!!!!

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