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CHAPTER 5

CHAPTER 5. The Structure of Atoms. Fundamental Particles The following three _____________ particles make up atoms. The table below lists these particles together with their masses and their charges. . Structure of the Atom Videos. 1. The earliest models

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CHAPTER 5

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  1. CHAPTER 5 The Structure of Atoms

  2. Fundamental ParticlesThe following three _____________particles make up atoms. The table below lists these particles together with their masses and their charges.

  3. Structure of the Atom Videos 1. The earliest models http://www.youtube.com/watch?v=BhWgv0STLZs&feature=player_embedded 2. Smaller than the Smallest http://www.youtube.com/watch?v=WmmglVNl9OQ&feature=player_embedded 3. The Rutherford Model http://www.youtube.com/watch?v=FfY4R5mkMY8&feature=player_embedded 4. The Bohr Model http://www.youtube.com/watch?v=hpKhjKrBn9s&feature=player_embedded 5. Spectra http://www.youtube.com/watch?v=5z2ZfYVzefs&feature=player_embedded 6. Wave Mechanics http://www.youtube.com/watch?v=1bpG1lEjJfY&feature=player_embedded Take notes over each video. Check calendar for due date.

  4. The Atomic Weight Scale & Atomic Weights define mass of 12C as 12 amu exactly 1 ____________= (1/12) mass of 12C Ex. 1) Calculate the number of atomic mass units in one gram. mass of one 24Mg atom = 24.3050 amu experimentally determined 1 mol of 24Mg atoms = 24.3050 g

  5. __________________- weighted average of the masses of its constituent isotopes • Ex 2) Naturally occurring chromium consists of four isotopes. It is 4.31% 2450Cr, mass = 49.946 amu, 83.76% 2452Cr, mass = 51.941 amu, 9.55% 2453Cr, mass = 52.941 amu, and 2.38% 2454Cr, mass = 53.939 amu. Calculate the atomic weight of chromium.

  6. Ex. 3)Naturally occurring Lithium exists as two isotopes, 6Li (mass = 6.015 amu) and 7Li (mass = 7.016 amu). The atomic weight is 6.941 amu. Which isotope is more abundant? Why?

  7. Ex 4) The atomic number of boron is 10.811 amu. The masses of the two naturally occurring isotopes 510B and 511B, are 10.013 and 11.009 amu, respectively. Which isotope is most common? Calculate the fraction and percentage of each isotope. • requires a little algebra • remember X + (1-X) = 1

  8. Ex 5) Nickel has five isotopes that occur in the following percentages and isotopic masses. What is the isotopic mass of 60Ni? IsotopeMass (amu)% 58Ni 57.935 68.27 60Ni ? 26.10 61Ni 60.931 1.13 62Ni 61.928 3.59 64Ni 63.928 0.91

  9. Electronic ConfigurationsRules for assigning e- in orbitals: • Always fill orbitals in ________energy level first. (Aufbau Principle) __________________________- The electron that distinguishes an element from the previous element enters the lowest energy atomic orbital available. (in other words fill one energy sublevel before moving up) • No two e- can have _________4 quantum numbers in an atom. (____________________________________) Wolfgang Pauli - 1925 • No two electrons in an atom may have identical sets of 4 quantum numbers.

  10. _____________e- out on a sublevel if possible. (Hund’s Rule) Electrons will spread themselves out among the orbitals individually and give unpaired, parallel spins. The pairing of electrons is an __________________process; energy must be __________________in order to make it occur. Exception: If you can achieve full or half-full orbitals by moving one e- between s ~ d or s ~ f orbitals, do so. It’s ______in energy because there is an increased _____________due to the decrease in the screening of electron/nuclear attractions

  11. Electronic Configurations

  12. use periodic chart - best method

  13. Electronic Configurations and Orbital Diagrams 1st row Orbital Order 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s

  14. 2nd row

  15. 3rd row

  16. 4th row

  17. 4th row continued

  18. 4th row continued

  19. Mass Spectrometry & Isotopic Abundances • ______________________is an analytical technique that measures the mass-to-charge ratio of charged particles. It is most generally used to find the ____________of a sample by generating a mass spectrum representing the masses of sample components. The ____________________is measured by a mass spectrometer. http://www.youtube.com/watch?v=J-wao0O0_qM

  20. This technique is applicable in: • ___________unknown compounds by the mass of the compound molecules or their fragments • determining the _______________________of elements in a compound • determining the structure of a compound by _________________its fragmentation • ______________the amount of a compound in a sample using carefully designed methods • studying the fundamentals of gas phase ion chemistry (the chemistry of ions and neutrals in vacuum) • ________________other important physical, chemical, or even biological properties of compounds with a variety of other approaches

  21. Electromagnetic Radiation relationship for electromagnetic radiation c = l u c = ____________________= 3.00 x 108 m/s

  22. Max Planck - __________ • energy is quantized • light has particle character • Planck’s equation

  23. Ex. 6) What is the frequency of green light of wavelength 5200 Å?

  24. Ex. 7) What is energy of a photon of green light with wavelength 5200 Å?

  25. Photoelectric Effect _____________– have mass, volume, and are countable. _____________– light composed of particles light has _______________________behavior light can strike the surface of some metals and cause an electron to be ejected Ex. ~ electronic door openers ~ light switches for street lights ~ exposure meters for cameras

  26. Albert Einstein explained the ____________________________in 1905 • 1921 Nobel Prize in Physics • electrons are _______________b/c energy from a photon transfers to e- during collisions. If you increase energy, more electrons get kicked off. Each individual photon makes a spark, 1 e- per photon. The more intense the light, the more photons. Light strikes the surface of various metals and causes ______________to be ejected.

  27. Atomic Spectra ________________________ electric current passing through a gas in a vacuum tube (at very low pressure) causes the gas to_______light emission or bright line spectrum

  28. ___________________________ shining a beam of white light through a sample of gas gives an ______________spectrum shows the wavelengths of light that have been ____________

  29. Spectra are fingerprints of elements use spectra to __________elements can even identify elements in_____

  30. The Origin of Spectral Lines Light of a characteristic wavelength (& frequency) is ________when electron ____from ________E (orbit) to ________E (orbit) origin of emission spectrum light of a characteristic wavelength (& frequency) is ____________when electron ________from ________E (orbit) to _________E (orbit) origin of absorption spectrum

  31. Atomic Spectra • how atoms ________to us” • we have to interpret their language • Bohr, Schrodinger, and Heisenberg were some of the first scientists to translate the language of atoms

  32. Ex. 8) An orange line of wavelength 5890 Å is observed in the emission spectrum of sodium. What is the energy of one photon of this orange light?

  33. Quantum Mechanics • Werner Heisenberg - 1927 • ________________________________ • It is ________________to determine simultaneously both the position & momentum of an electron. Why? The act of measuring a very small particle changes its position, so it is _____________to precisely determine both the ___________and _______________of that object. • electron microscopes use this phenomenon • devices for detecting motion of electron disturbs its position

  34. Quantum Numbers ______________numbers are description of the orbitals; solutions of the Schrodinger, Heisenberg & Dirac wave equations the quantum #’s help ________________the solutions

  35. There are four ___________numbers which describe the relative position and energy of an electron in an atom. 1st____________quantum number 2nd____________________quantum number 3rd______________quantum number 4th_______quantum number

  36. Principal Quantum Number • Symbol “_____” – refers to energy level n = 1, 2, 3, …  • The principal quantum number describes the ________________from the nucleus. It is often referred to as ______________or _______ • electron’s ________depends principally on n

  37. Angular momentum, 2nd quantum number • angular momentum, tells __________of the atomic orbitals • _______________- ________of space where the _________________of finding an electron around an atom is _____________ ~ volume that the electrons occupy ___________of the time

  38. How to solve for Angular momentum • symbol ___ to find ℓ plug into n-1 If n=1 ℓ =0 If n=2 ℓ = 0, 1 If n=3 ℓ = 0, 1, 2 If n=8

  39. Orbital symbols for ℓ • represents the ______within an energy level: s, p, d, f (code letters for the shapes of orbitals) • s=0 • p=1 • d=2 • f=3 • Quantum number -ℓ (in theory) If ℓ = 0, 1, 2, 3, 4, 5, .......(n-1) Then ℓ = s, p, d, f, g, h, .......(n-1)

  40. s orbitals s orbitals are __________in shape. Every energy level has an s orbital s orbitals have angular momentum quantum number (l) equal to 0. For s:

  41. p orbitals p orbitals are shaped like dumbbells or peanuts. They are oriented along the x, y, and z coordinates. ______________________ They have an angular momentum quantum number (l) equal to 1. For p: 3 per n level, px, py, pz

  42. p orbitals

  43. d orbitals _______________________ 4 clover leaf shaped and 1 peanut shaped with a doughnut around it on Cartesian axes and rotated 45o For d: 5 per n level

  44. d orbitals

  45. f orbitals __________________ most complex shaped orbitals 7 per n level, complicated names For f: important effects in lanthanides & actinides

  46. f orbitals

  47. Magnetic quantum numbers • 3rd quantum number • symbol ml • Helps tell _______________of orbitals ml= - l to + l • Look at _____________________to help you with ml

  48. theoretically, we can continue this series on to g, h, i, orbitals l=0 ml=0 • only 1 value for s orbital l=1 ml= -1, 0, 1 • 3 values for p orbitals l=2 ml= -2, -1, 0, 1, 2 • 5 values for d orbitals l=3 ml= • 7 values for f orbitals

  49. Spin Quantum Number • 4th quantum number, symbol = _______ • ms = +1/2 or -1/2 • tells us the ________and _____________of the ____________field of the ____________

  50. spin effects • every orbital can hold up to two electrons • one spin up ­ one spin down¯ • spin describes the ______________of their ________________field • e- have charges • two _________________magnetic states

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