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 + O 2  SO 2 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: NO 2 NO N 2 O

7. Dalton’s Atomic Theory 1.Matter is made of indivisible & indestructible atoms 2.Atoms of a given element are identical in their properties 3.Atoms of different elements differ in their properties

8. Dalton’s Atomic Theory 4.Atoms of different elements combine in simple whole-# ratios to form cmpds 5.Chemical rxns consist of the combination, separation, or rearrangement of atoms.

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 Modifications to Dalton’s Theory 2 principles no longer valid –subatomic particles –overlooked atoms combining w/ their own type

10. Atomic Mass p + + n 0 (e- mass negligible) Units: atomic mass units (amu) Exactly 1/12 the mass of 1 carbon-12 atom

11. 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

12. Mole (mol): amt of substance Avogadro’s constant: 6.02 x 10 23 particles 1 mol 1 g/mol = 1 amu

13. 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 10 23 = 18.9984 g/mol 1 mol

14. (3-2) Subatomic Particles Smaller particles that make up an atom 3 types

15. ParticleLocationSizeCharge Electron (e - ) Outside nucleus 0.000 549 amu Negative Proton (p + ) Nucleus1.007 amu Positive Neutron (n 0 ) Nucleus1.009 amu Neutral

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

18. Cathode Ray Tube Experiment J.J. Thomson –e - had mass –e - had negative charge

19. Nucleus Central region of an atom containing p + & n 0 Plum-pudding model: Thomson –e - embedded in positively charged ball of matter

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

22. Atomic Number # of p + in the nucleus of an atom Mass #: total # of p + & n 0 in the nucleus 4 2 He: mass # = 4, atomic # = 2 –2 p +, 2 n 0, 2 e -

25. 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

26. Isotopes Atoms of the same element w/ different #’s of n 0 –Ex: Helium-3 (1n, 2p), Helium-4 (2n, 2p) Radioisotope: unstable atom that undergoes radioactive decay

27. (3-3) Electromagnetic Spectrum Total range of electromagnetic radiation –e - have properties of both particles & waves

28. Wavelength λ: distance b/w 2 consecutive peaks or troughs –m

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

30. Speed of Light c = 3.0 x 10 8 m/s Speed of light = freq. x wavelength c = v λ –Ex: v = _c_ = 3.0 x 10 8 m/s λ 7.6 x 10 -7 m = 3.9 x 10 14 /s = 3.9 x 10 14 Hz

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

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

34. 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

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

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

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

40. Electron Configuration Description of occupied e - orbitals in an atom s (1 orbital), p (3), d (5), f (7) F: 1s 2 2s 2 2p 5 Main E level, orbital, # of e - sp s d f

41. 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

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

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

44. Noble Gas Configuration Electron Config.: S: 1s 2 2s 2 2p 6 3s 2 3p 4 Noble Gas Config.: S: [Ne]3s 2 3p 4 Unless specified do not use noble gas configuration!!!!