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CHEM 121 Chapter 2

CHEM 121 Chapter 2. Winter 2015. Elements and Symbols. Elements: Chemical symbols Ex. cobalt = nitrogen =. Elements. 8A. 1A. 2A. Ordered by atomic number “Periodic” trends Periodic table by Mendeleev (1871). 3A. 4A. 5A. 6A. 7A. 8B. 3B. 4B. 5B. 6B. 7B. 1B. 2B.

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CHEM 121 Chapter 2

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  1. CHEM 121Chapter 2 Winter 2015

  2. Elements and Symbols • Elements: • Chemical symbols • Ex. cobalt = nitrogen =

  3. Elements 8A 1A 2A • Ordered by atomic number • “Periodic” trends • Periodic table by Mendeleev (1871) 3A 4A 5A 6A 7A 8B 3B 4B 5B 6B 7B 1B 2B

  4. Some unusual element symbols • Au • Ag • Fe • Pb • Cu • Sn • K • Na

  5. Reading the Periodic Table Period: Group: Alkali metals: Alkaline earth metals: Halogens: Noble Gases:

  6. Metals, Nonmetals, and Metalloids • Metals: • Nonmetals: • Metalloids: • B, Si, Ge, As, Sb, Te, At

  7. Carbon Three elemental forms Interesting bonding with many elements Diamond Graphite Buckyball

  8. Element Song • Meet the elements: http://www.youtube.com/watch?v=Uy0m7jnyv6U&feature=related • All of the elements: http://www.youtube.com/watch?v=zGM-wSKFBpo&feature=related

  9. Elements of Life C N O H

  10. Other life elements Major minerals (macronutrients) Fluids: Na K Cl Proteins: Mg S Teeth & Bone: Ca P Trace elements (micronutrients) Fe Zn I F Se

  11. Molecules Molecules: Compounds: Chemical formula: How many atoms? • NaCl • H2O • CsCl2 • H2O2 • Ca(OH)2

  12. 3-minute practice How many of each type of atom is in one molecule of ammonium phosphate?

  13. Atoms and Subatomic Particles Diameter of one atom: 0.1 – 0.5 nm Charge Mass (g) Mass (amu) Location amu: atomic mass unit (1/12 C atom mass)

  14. Atomic Number and Mass Number • Atomic Number (Z) • Atoms are electrically neutral • Mass Number (A)

  15. 3-minute practice How many protons, electrons, and neutrons are in each of the following: • Z = 14 A= 29 • An atom with a nucleus with 4 protons and 5 neutrons? • A potassium atom with a mass number of 39?

  16. Isotopes Isotopes: Atomic Symbol 24 Mg 12

  17. Isotopes of Carbon 12C : 6 protons + 6 neutrons 13C : 6 protons + 7 neutrons 14C : 6 protons + 8 neutrons 98.89 % 1.11 % <0.01 % All have nearly identical chemical behavior

  18. 3-minute practice How many protons, neutrons and electrons does each of the following have? • 35Cl • 37Cl • C-14

  19. Atomic Mass weighted average of masses of all the naturally occurring isotopes of that element Example: chlorine Contribution to average Cl atom Mass (amu) x Abundance (%) = 35Cl x = 37Cl x =

  20. Relative Masses of Atoms Atoms are too small to measure actual mass Compare masses of atoms using relative mass An average Zn atom is ~ 3x more massive than an average Na atom

  21. Medical Use of Isotopes I-131

  22. Reading the Periodic Table Period: horizontal row Group: vertical column Elements in the same group have similar chemicalproperties because they have the same number of outer shell e- • Each e- in an atom “sits” at an energy level (n)

  23. Energy States • Ground state: • n = 1 • Excited states: • n = 2, 3, 4,… • Photon emitted: • Photon absorbed:

  24. Energy Sublevels • Each level consists of sublevels • # of sublevels in each level = level number • n = 1  • n = 2  • n = 3  • n = 4  Increasing energy of sublevels within an energy level:

  25. Disneyland Analogy

  26. Orbitals • Regions with the highest probability of finding an electron • Each type of orbital has a given shape: s orbital p orbitals

  27. Orbitals d orbitals Each orbital can hold _____ electrons • s orbitals: • p orbitals: • d orbitals:

  28. Orbitals f orbitals http://int.ch.liv.ac.uk/Lanthanide/Ln_Chemistry_folder/Miscellaneous%20folder/Miscellaneous.html#f_orbitals

  29. 5-minute practice • How many sublevels are in the n = 3 energy level? • What are these sublevels? How many of each type are there? • How many electrons can be held in the n = 3 energy levels?

  30. Orbital Energy Levels • Pauli Exclusion Principle: • Electrons want to sit in lowest energy level • For a given n value: Order of sublevel energy: s < p < d < f • Orbital Diagrams

  31. Electron Configurations tell us which orbitals electrons are in for a given atom Example: Hydrogen Atomic Number: (How many electrons?) Orbital Diagram: 1s Electron Configuration:

  32. Electron Configurations Example: Helium Atomic Number: (How many e-?) Orbital Diagram: Electron Configuration: Example: Lithium Atomic Number: 1s 1s 2s (How many e-?) Orbital Diagram: Electron Configuration:

  33. Electron Configurations Example: Boron Atomic Number: (How many electrons?) 2p Orbital Diagram: 1s 2s Electron Configuration:

  34. Electron Configurations Example: Oxygen Atomic Number: (How many electrons?) 2p Orbital Diagram: 1s 2s Electron Configuration: Abbreviated Configuration:

  35. Electron Configurations relate to the Periodic Table! • s block elements: end with s orbital Na: • p block elements: end with p orbitals P: • d block elements: end with d orbitals Ni: Note: 4s orbital comes before3d orbital

  36. Sublevel Order

  37. 5-minute review Write the abbreviated electron configuration for the following: • K • S • Br • Ar • Cs

  38. Periodic Trends Valence electrons: Boron (B): How many valence electrons?

  39. Periodic Trends Aluminium (Al): How many valence electrons? Chlorine (Cl): How many valence electrons?

  40. Electron Dot Symbols Lithium Valence electrons? Carbon Valence electrons? Fluorine Valence electrons?

  41. 5-minute review Draw electron dot symbols for the following: • Sulfur • Potassium • Beryllium • Silicon

  42. Elements 8A 1A 2A • Elements ordered by atomic number • “Periodic” trends • Periodic table by Mendeleev (1871) 3A 4A 5A 6A 7A 8B 3B 4B 5B 6B 7B 1B 2B

  43. Atomic Size Atomic radius:

  44. Ionization Energy Ionization:

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