Miss Nevoral by X34e3B

VIEWS: 0 PAGES: 4

									Miss Nevoral
Science 9
http://fc.sd23.bc.ca/~lnevoral/


                        Chapter 3 – Elements into Compounds
                                      Pages 76-99

                                          KEY

Section 3.1 – Compounds

    1. What are compounds and chemical bonds? Compound is a pure substance
       made up of two or more elements that have been chemically combined.
       Chemical bonds are links between tow or more atoms that hold the atoms
       together.

    2. What is a molecule? A group of atoms in which the atoms are bound
       together by the sharing of one or more pairs of electrons.

    3. Define covalent compounds: Two atoms share a pair of electrons. Always
       with non-metals.

    4. Give some examples of covalent compounds. Water, CO2, CO

    5. Draw the Bohr model diagram of water using Figure 3.2A and 3.2B page 78 in the
       space below.




    6. Define ionic compounds: Oppositely charged ions come together because
       of a mutual attraction. + and – charges attract.

    7. All ionic compounds consist of positive ions and negative ions.

    8. What is the difference between covalent and ionic compounds? Covalent bonds
       share electrons while ionic compounds have opposite charges attract.




                                            1
  9. Define polyatomic ions: A molecular ion composed of more than one type
     of atom joined by covalent bonds.

  10. Give an example of a polyatomic ion. Dichromate, hydroxide, sulphate,
      sulphite etc.

  11. What does the prefix “poly” mean? many

Section 3.2 – Names and Formulas of Ionic Compounds

  1. What does a chemical name indicate? The name of the compound that
     indicates the elements in it.

  2. What does IUPAC stand for? What is this group responsible for? Internation
     Union of Pure and Applied Chemistry. Responsible for the rules for
     naming compounds.

  3. When naming ionic compounds, which ion comes first, the positive or negative ion?
     What are metals; positive or negative ions? What are non-metals; positive or
     negative ions? Positive ion (metal) comes first, then the negative ion (non-
     metal)

  4. What suffix is added to non-metal ion’s name? “ide”

  5. Do Practice Problems page 86 (Writing names of compounds) on a separate
     piece of paper. Answer on page 509 of the text book

  6. Define chemical formula: Contains the symbols and relative numbers of
     ions in a compound. Example: Na2O

  7. What does subscript mean? Sub = below and script = write.

  8. What needs to balance in an ionic compound? The charges

  9. Do Practice Problems 1 & 2 page 87 (Writing formulas of compounds) on a
     separate piece of paper. Answer on page 509 of the text book

  10. Define multivalent metals: metals that can form an ion in more than one
      way, resulting in different ions with different charges. Multi means
      many.

  11. Give three examples of elements that have more than one ion to combine with.
      Iron (Fe 2+ and 3+), Chromium (2+ and 3+), Titanium (4+ and 3+)




                                          2
12. How do we distinguish between two ions formed from multivalent metals? By
    using Roman numberals.

13. Fill in the Table below showing the metal ion charge to it’s corresponding Roman
    numeral

                           Metal Ion          Roman
                             Charge          Numeral
                                1+               I
                                2+               II
                                3+              III
                                4+              IV
                                5+               V
                                6+              VI
14. What does the Roman numeral reveal about an ion? The Roman numeral
    tells you that first of all you have more than one ion that can combine for
    that particular metal; and two what charge is on the metal ion.

15. Do Practice Problems page 89 (Writing formulas for compounds with multivalent
    metals) on a separate piece of paper. Answer on page 509 of the text book

16. Describe how you name compounds that contain a multivalent metal. First, you
    write the metal name first. Then, once it’s been decided which ion you
    are using for the metal, you place the Roman numeral that corresponds
    with that metal in bracket after the metal name. Last you write the non-
    metals name, not forgetting to put “ide” at the end of it’s name.

17. Do Practice Problems page 90 (Writing the names of multivalent metals) on a
    separate piece of paper. Answer on page 509 of the text book

18. Define polyatomic ion: A covalent bond of more than one type of atom.
    Poly means many. Will act as one group. Carry an electric charge;
    therefore, must bond with an ion with an opposite charge.

19. Give 5 common polyatomic ions. Acetate, chromate, nitrate, nitrite,
    phosphate.

20. Why are brackets used when dealing with polyatomic ions? So that then relative
    number of polyatomic ions stays intact if there is more than one need to
    bond with a metal. If only one polyatomic ion, then can drop the
    brackets.

21. What charge do most polyatomic ions have? negative




                                         3
Section 3.3 – Physical and Chemical Changes

  1. Define physical change: Changes that occur where the appearance of the
     substance may change, but no new substances are produced.

  2. In a physical change, are the bonds holding the atoms together in a molecule
     broken? NO

  3. Give some examples of physical changes. Melting, ripping, cutting, grinding,
     tearing, dissolving, any changes in states of matter.

  4. Are changes in states of matter a physical or chemical change? physical

  5. Define chemical change: Chemical changes produce new substances with
     new properties; in other words, the atoms of the original substance have
     been rearranged into a new substance.

  6. What is the starting off materials of a chemical reaction called? What are the new
     substances produced called? Reactants  Products

  7. What are   the clues that a chemical change has occurred?
               Colour change
               Heat, light, sound produced (or consumed)
               Bubbles of gas form (fizzing)
               A precipitate (solid) may form

  8. Identify each of the following processes as either a chemical change or physical
     change:
                 i. boiling water -     physical
                ii. rusting of nails -  chemical
               iii. tearing clothes -   physical
               iv. lighting a match - chemical

  9. Define an exothermic process: An exothermic process is when energy or
     heat/light is released.

  10. Define an endothermic process: An endothermic process is when energy is
      being absorbed by the system to produce a reaction.

  11. What does “exo” mean? What does “endo” mean? Exo = leaving; Endo =
      entering




                                           4

								
To top