Day 7 in SCI110: Chemistry

• Spring 2005 Schedule

• Last time: Wrap up
  • Regression analyses for tree ring experiments
  • Discussion of pendulum questions
  • Hand back investigation of a claim papers.
  • Hand back quizzes, and go over results.
  • The Periodic Table
    • The Periodic Table (with Tim and Moby)
    • chemicalelements.com
    • One page periodic table guide
  • Experiment: separating metals from non-metals

• Today:

  • Discussion of the periodic table, and electron configurations
    • The elements:
      • alkali metals - soft, shiny metals; highly reactive
      • alkaline earth metals - reactive, but not so much
      • transition metals
      • semimetals
      • non-metals, including the

        • halogens - "salt formers"

          react with metals to form salts

        • noble gases
    • The periods
      • Start with a single electron in the outer shell
      • End with a full shell (in a noble gas)
    • The families
      • all have the same number of electrons in the outer shell (with the exception of helium)
      • A-group are called the main-group or representative elements
      • B-group are called the translational elements

    • Electron theory of chemical bonding asserts that

      the outer orbital electrons are mostly responsible for the chemical properties of an element.

    • Electron dot notation

      represents the number of outer shell electrons an element has

    • ions
      • when an atom loses or gains electrons, it acquires an unbalanced electron charge and is called an ion.
      • Elements with one, two or three outer electrons tend to lose them; those with five, six, or seven outer electrons tend to gain them.
      • losing electrons makes one a positive ion
      • gaining electrons makes one a negative ion

  • Discussion of results of experiment:
    • Metals show:
      • malleability
      • ductility
      • luster
      • conductivity
    • Problems? Observations?
    • t-test of results for solubility

  • Discussion of reading, chapter 9: 172-181
    • Tim and Moby
    • Element - pure substance, cannot be decomposed; smallest unit, the atom
    • Compound - made up of several elements; smallest unit, the molecule
    • Physical change - hammering, evaporization, melting, crushing, dissolving....
    • Chemical reactions - a change in which different chemical substances are created by forming or breaking chemical bonds
      • chemical energy - used or released
      • chemical equation - inputs and outputs
    • Valence electrons - electrons in the outer shell
    • Chemical bond - an attractive force that holds atoms together in a compound
      • ionic bonds - atoms transfer electrons
      • ionic compounds - compounds held together by ionic bonds:
        • NaCl
        • MgF₂
      • covalent bonds - atoms share electrons
        • H₂
        • F₂
        • double bond: C₂H₄
        • triple bond: C₂H₂
      • metallic bonds - shared "electron sea"
    • QFT (Questions for Thought): p. 193, 1, 3, 4

    • Parallel Exercises, p. 193: Group B, 1-3

  • Experiment - physical and chemical changes -- p. 36-38

• Homework:
  • Take the chemical versus physical property quiz
  • Take the chemical versus physical change quiz (study up with their guide first!)
  • Use this sheet as one guide for understanding the chemistry we do in this class.
  • More reading! Chapter 8: 152-161; Chapter 10: 197-198

Links:

• An experiment on physical and chemical change that you can try at home!
• What is the difference between a physical change and a chemical change?