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Chemistry: Building Blocks & Forces

Explore the building blocks of chemistry such as atoms, molecules, and subatomic particles, and learn about the forces at work in chemical reactions. Discover the properties of carbon, nitrogen, oxygen, and hydrogen and understand their roles in the molecular shape. Dive into Lewis structures, VSEPR theory, and hybridization to understand the structure of compounds and predict their stability and properties. Discover the role of electronegativity and polarity in compounds and learn about the forces and energy involved in chemical reactions.

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Chemistry: Building Blocks & Forces

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  1. Atoms • Carbon • Hydrogen • Oxygen • Nitrogen • Phosphorus • Chlorine Molecules • Methane • Formaldehyde • Hydrogen cyanide • Phosphorus pentachloride What are the building blocks? • Subatomic particles • Protons • Electrons • s orbital • p orbital • d orbital • Hybrids

  2. Electron: Both wave and particle

  3. Electron: Both wave and particle

  4. It’s all aboutbuilding blocks CHEMISTRY

  5. Carbon Nitrogen Oxygen Hydrogen 4 3 2 1 Number of available connections (bonds)

  6. H Methane C H H H

  7. Methanol H C O H H H

  8. FORCE & ENERGY The forces at work are: Electromagnetic: Repulsion of like charges: proton-proton and electron-electronAttraction of unlike charges:proton-electron. Magnetic: Electron spin introduces magnetic forces. Electrons with opposite spins produce opposite magnetic poles. Opposite magnetic poles attract. Opposite spin is required for electrons to occupy the same orbital. N S S N

  9. Lewis Structures & Molecular Shape

  10. Lewis Structures Gilbert Lewis

  11. Lewis Structures • Keeps track of valence (bonding) electrons • Predicts formula for many compounds • Predicts charge of compounds • Predicts stability of compounds • Predicts molecular shape if combined with other theories. nitrate=NO3-

  12. Why interest in Molecular Shape? δ- δ- • Predicts polar compounds (ones with ends with opposite charges) • Predicts solubility • Predicts interaction with light (link) • Predicts crystal structure δ+ δ- δ- δ+ δ- δ-

  13. H C H H H Methane building blocks C H H H C H H Lewis Structure VSEPR Valence Shell Electron Pair Repulsion

  14. Carbon 1s2 2s2 2p2 s p d f

  15. 3 sp 1s 2s 2px 2py 2pz sp3 sp3 sp3 sp3 y Hybridize Promote x 109.5o z Methane: Carbon

  16. VSEPR • http://www.chem.purdue.edu/gchelp/vsepr/ • http://www.shef.ac.uk/chemistry/chemputer/vsepr.html • http://www.chemistry.wustl.edu/~edudev/Vsepr/table1.html • http://intro.chem.okstate.edu/1314F00/Lecture/Chapter10/VSEPR.html

  17. Orbitals • http://www.mpcfaculty.net/ron_rinehart/orbitals.htm

  18. Lewis Structures • http://www.stolaf.edu/depts/chemistry/courses/toolkits/121/js/lewis/

  19. PF3 5 + 7x3 = 26 valence electrons 1 2 3 4 5

  20. P F P F P F F P F F F F F P F Magic 8 4 groups of electrons, which will repel each other.

  21. P P F PF3 F F s p 1s2 2s2 2p63s2 3p3 d f

  22. F F P F 4 groups of electrons, which will repel each other. 1 central atom=A 3 bonding atoms = B3 1 non-bonding pairs of electrons = N AB3N -

  23. AB3N

  24. AB3N

  25. F F P F Hybridization

  26. Polar? δ+ P F δ- F δ- F δ- P = 2.1 F = 4.0 Electronegativity

  27. SCl2 6 + 7x3 = 27 valence electrons 1 2 3 4 5

  28. Cl S Cl S Cl Cl Cl Cl S Magic 8 S Cl - 4 groups of electrons, which will repel each other.

  29. Cl Cl S 4 groups of electrons, which will repel each other. 1 central atom=A 2 bonding atoms = B2 2 non-bonding pairs of electrons = N2 AB2N2 -

  30. AB2N2

  31. Cl Cl S Hybridization Cl Cl S

  32. Cl Cl S Polar ? δ+ δ- δ- S = 2.5 Cl = 3.0 Electronegativity

  33. CS2 4 + 6x2 = 16 valence electrons 1 2 3 4 5

  34. S C S S C S S S C Magic 8 C S - 2 groups of electrons, which will repel each other.

  35. S S C VESPR Sketch 2 groups of electrons, which will repel each other. 1 central atom=A 2 bonding atoms = B2 Zero non-bonding pairs of electrons AB2 -

  36. AB2

  37. S S C Hybridization for carbon Straight Trigonal Tetrahedral Trigonal bipyramidal Octahedral for sulfur

  38. S C S N H C 1s 2s 2px 2py 2pz sp sp Hybridized Promoted sp Linear 2s + 2px Carbon in hydrogen cyanide or carbon disulfide:

  39. S S C Polar ? S = 2.5 C = 2.5 Electronegativity

  40. KrF2 8 + 7x2 = 22 valence electrons 1 2 3 4 5

  41. Kr F Kr F F F F F Kr Violated Magic 8 F Kr OK for period 3 elements or higher 5 groups of electrons, which will repel each other. -

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