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					Grade 9 Science                         Unit V; Chemistry
                                                                       Chemistry Unit Outcomes

At the end of this unit , you should be able to:

1.     Define element as a pure substance that cannot be decomposed.
2.     Define compound as a pure substance that consists of two or more elements combined in
       a fixed proportion.
3.     Identify examples of elements and compounds.
4.     Use the atomic theory to distinguish between atoms and molecules.
5.     Distinguish between elements and compounds:
               -type of atoms
               -ability to decompose
               -abundance in nature

6.     Identify the chemical symbols for a number of common elements.
7.     Identify and interpret chemical formulae for several common compounds.
8.     Describe the relationship between the three subatomic particles: protons, neutrons, and
9.     Illustrate models of various atoms.
10.    Determine the number of protons and electrons in an atom when given its atomic number.
11.    Recognize that the columns in the periodic table contain elements with similar properties.
12.    Use the periodic table to identify families of elements.
13.    Use the periodic table to locate the general position of metals.
14.    Pure substances, when combined, may undergo a physical or chemical change.
15.    Distinguish between a physical and chemical change.
16.    Describe the characteristics of a chemical change.
17.    Provide examples of physical or chemical change.
18.    Explain the importance of physical and chemical changes in our everyday life.
19.    A chemical change results from a chemical reaction which involves reactants and
20.    Distinguish between the reactants and products in a simple chemical reaction.
21.    Use word equations to describe simple chemical reactions.
22.    Investigate and assess the Law of Conservation of Mass in specific chemical reactions.
23.    Use chemical tests to identify the product(s) formed in a chemical reaction.
24.    Investigate and describe the reaction between an acid and a base.
25.    Relate the pH of a solution to its acidity.
26.    Measure the pH of various solutions.
27.    Determine the effect of temperature, concentration, and surface area on the rate of a
       chemical reaction.
28.    Describe how changes in reaction rates can prove useful in our daily lives.
Obj. 1          Elements

       Atom -        The smallest, indivisible particles of elements.

       Element -     a pure substance which cannot be decomposed ( broken down) into
                     simpler substances. Elements are made up of only one kind of atom.

Obj. 2 : Compounds

       Molecule -    a stable particle formed when two or more nonmetal atoms of the same
                     type combine. eg. O2, (oxygen gas), N2 (nitrogen gas), S8 (sulphur)

       Compound - a pure substance that is made up of 2 or more types of atoms combined (
                  bonded together) in fixed proportions. eg. C6H12O6 (glucose), NaCl (salt),
                  CO2 (carbon dioxide)

Obj 3:          Examples of Elements and Compounds

Examples of Elements                             Examples of Compounds

Gold                                             water

Copper                                           sugar (sucrose, glucose)

Iron                                             alcohol
 Oxygen                                            salt (sodium chloride)

 Chlorine                                          rubber

 Silver                                            steel

 Lead                                              carbon dioxide

 Iodine                                            hydrogen peroxide

 Hydrogen                                          iron oxide (rust)

Obj. 4:                               The Atomic Theory

          The atomic theory helps to explain the difference between elements and compounds. It
1.               All matter is made up of tiny particles called atoms.
2.               Atoms of one type are all the same. Atoms of different types are different from
                 each other.
3.               Atoms can combine with other atoms to form larger particles called molecules.
                 (this is based on certain “rules” of nature)
4.             Atoms are not created or destroyed by ordinary forces in nature.

Elements and Compounds:

       As the atomic theory stated, atoms cannot be decomposed (broken down) but compounds
can. The compound water, for example, is made up of hydrogen and oxygen atoms bonded
together. We can put water through a chemical reaction to make it break down into hydrogen
and oxygen. However, we cannot decompose copper; it is an element. Compounds can be
decomposed, elements cannot.
       Because of the ability of elements to combine to form compounds, a great variety of
compounds are possible. There are many times more compounds present in nature than there are

Obj. 6                        Chemical Symbols (read p. 14)

      Chemists have developed a shorthand method for writing the names of elements. Each
symbol is either a capital letter or a capital letter followed by a small letter. Some of the most
common elements and their chemical symbols are:

       refer to p. 17, Table 7.1. Have students note this in their text.

       Calcium                 Ca
       Carbon          C
       Chlorine                Cl
       Copper          Cu
       Hydrogen                H
       Nitrogen                N
       Oxygen                  O
       Sodium                  Na
       Sulphur                 S
       Helium          He
       Aluminium               Al
       Neon                    Ne
       Argon           Ar
       Iron                    Fe
       Gold                    Au
       Silver                  Ag
       Potassium               K
       Fluorine                F

       The element names and all of their symbols are given on the periodic table of elements.
Obj. 7             Chemical Formulas of Compounds (read p. 15)

       A compound can be shown by a combination of chemical symbols called a chemical
formula. The chemical formula tells what elements (atoms) make up the compound. It also tells
how many of each type of element (atom) helps make up the compound. Subscript numbers
following each chemical symbol tell how many of each type of element is present.

eg. the chemical formula for a water molecule is H 2O. This formula tells us that one formula
unit of water is made up of 2 atoms of hydrogen bonded together with 1 atom of oxygen. If no
subscript number is shown after a chemical symbol, it means that there is one atom present.

       Assign students to do activity 1.5, p. 15

       Give further examples to work on:
              C6H12O6 - has 6 carbon, 12 hydrogen and 6 oxygen atoms
              FeO - has 1 Iron and 1 oxygen atoms
              NaCl - has 1 sodium and 1 chlorine atom
              Al2 O3 - has 2 aluminum and 3 oxygen atoms
              NaOH - has 1 sodium, 1 oxygen and 1 hydrogen atom
              KNO3 - has 1 potassium, 1 nitrogen and 3 oxygen atoms
              PbNO3 -has 1 lead, 1 nitrogen and 3 oxygen atoms.

        If we want to show that we have more than one compound molecule present, we can use
coefficients in front of the chemical formula:

       eg. 6H2O       -       this means there are 6 water molecules present.

       Q:     How many types of atoms are present in 6 water molecules, 6H 2O?

       A:     To get the answer, multiply the coefficient by the subscript numbers. 6 x 2 = 12
              hydrogen atoms and 6 x 1 = 6 oxygen atoms.

       Q:     Find the number and types of atoms in 4AlCl3.
       A:     4 x 1 = 4 aluminum atoms and 4 x 3 = 12 chlorine atoms.

       Some common chemical formulas you should learn are:

       02   -         oxygen gas
       CO2 -          carbon dioxide
       H2O2 -         hydrogen peroxide
       CH4     -       methane gas
       H2O     -       water

Obj. 8, 9 and 10; The Parts of the Atom ; Protons, Neutrons and Electrons
                  Models of the Atom’s Structure

       - read p. 16 for homework.

       - Watch video on the atom.

       The atom is composed three types of subatomic particles. They are:
1.             protons - subatomic particle located in the nucleus of the atom. It has a 1 +
               charge. Their symbol is p+.
2.             neutrons - subatomic particles having no electrical charge. They are located in
       the nucleus of an atom. Their symbol is n0.
3.             electrons - subatomic particles which rotate around the nucleus of an atom in
       fixed paths called orbitals. They have a 1 - negative charge. Their symbol is e-.

       Nucleus -       the tiny, solid, dense centre of an atom. It is composed of protons and
                       neutrons packed together. It makes up the atomic mass of an atom. Al of
                       the atom’s mass is in the nucleus. The nucleus has an over + charge
                       because of the protons there.

        The protons and the neutrons are held together to form the core of the atom. This central
core is called the nucleus of the atom. The electrons revolve rapidly around the nucleus in an
electron cloud in fixed orbitals. Because the nucleus is very tiny and the electrons revolve so far
away around it, most of the atom is empty space.

       Electron cloud -       the space around an atom’s nucleus through which the e- rotate in

       Orbitals -      fixed path which electrons follow around the nucleus of an atom (sort of
                       like the way planets follow orbits around the sun).

        The mass (weight) of the atom is in the nucleus, where the protons and neutrons are
stationed. The electrons are so tiny compared to the other particles that they hardly make up any
of the atom’s mass. Electrons are 2000 times lighter than protons and neutrons but an electrons
negative charge is equal in strength to a protons positive charge.

        An unbonded atom is said to be neutral in charge. This means that every unbonded atom
has an equal number of electrons and protons. Because of this equal number of + and - charges,
they cancel each other out. (See table on p. 17)
           Eg an unbonded chlorine atom has 17 p+ and 17 e- overall charge is 0.

               Atom Model
                                                                              Electron cloud with
                                                                              Solid nucleus (protons
                                                                              and neutrons)


Homework: Read pages 16 - 17. Answer checkpoint questions 4, 5, and 7 on p. 18 - 19.

                What makes one type of atom different from another type of atom?

       Different atoms have different numbers of electrons, protons and neutrons. Each type of
atom has its own atomic mass. Every atom has its own atomic number.

Atomic number -          a number on the periodic table that tells you how many protons an atom
                         has. It also tells you how many electrons an unbonded atom has. The
                         atomic number identifies an atom. Every atom has its own atomic

           Look at the KEY on your PT. It shows you which number is the atomic number. The
atomic number for Carbon, C, is 6. This tells us that an atom of carbon has 6 protons and 6

Exercise:     Look up the atomic number for each element:

             Atom                # of protons                    # of electrons
 Manganese, Mn                   25                              25
 Iron, Fe                        26                              26
 Gold, Au                        79                              79

Exercise: State the atomic number and the atomic mass of the following elements:

 atom                            Atomic number
Obj 11 - 13             The Periodic Table of Elements ( the P.T.)

      The periodic table is divided into rows (across) called periods and columns (up and
down) which are called family groups. See the periodic table in your text book appendix.

Periods -      rows on the periodic table.

Family groups - columns on the periodic table.

       Each family group is given a roman numeral at its top.

       Exercise: State the family group number of each of the following atoms:

                           Atom                   Family group number

         The PT also divides the elements into metals or nonmetals by using the STEP. This is a
heavy zig - zag line on the PT. All elements to the left of the step line are metals. All elements
to the right of the step are nonmetals.

                       Metals                                         Nonmetals
 are ductile - they can bend without breaking     are not ductile
 are malleable - they can be stretched            are not malleable
 are shiny in lustre                              are dull with low lustre
 are good conductors of electricity               are poor conductors of electricity

Obj. 14 - 21                    Physical and Chemical Changes

      Physical change involves a state change in which no new chemicals are produced. The
chemical formula of the substance remains the same. The change is easily reversed.

       State - solid, liquid or gas.
         In chemistry we use symbols to show the state of a substance. The state symbols appear
after a chemical compound formula in brackets. The symbols are:
         (s) = state is solid
         (g) = state is gas
         (l)= state is liquid
         (aq) = aqueous (aqueous means that the substance is dissolved in water)

       eg.    Mg (s) - means solid magnesium

              PbI(aq) - means aqueous lead iodide.

              O2 (g) - means oxygen gas

              H2O (l) - means water in liquid state

       for example, the 3 states of water are:

       H2O (s)         = ice
       H2O (l) = water
       H2O (g)         = water vapour

       An example of a physical change would be the melting of ice to produce water:

       Eg.    Ice                           Water

              H2O (s)                       H2O (l)

      This change is easily reversed and, as you can see, ice and water both have the same
chemical composition, both are still H 2O.

       Chemical change -      a change in which one or more substances called reactants go
                              through a chemical reaction and produce different substances
                              called products. The products have different properties and
                              different chemical formulas than the reactants.

        Chemical change involves a chemical reaction. There are two main parts in a chemical
reaction, the reactants and the products.

Reactants -   chemicals that react. They are on the left hand side of the arrow in a chemical
Products -    chemicals produced by a chemical reaction. They are on the right hand side of the
              arrow in a chemical equation.

Eg.           2Mg (s) + O2 (g)                     2MgO (s)       (The  mean “yields or
              (REACTANTS)                           (PRODUCTS)

       This equation can also be stated in words. The word equation for this reaction is:

Word equation:        2 magnesium atoms react with 2 oxygen atoms to yield 2 molecules of
                      magnesium oxide

       Two types of chemical reactions (there are more but we will only look at 2 in Grade 9)

        1. Synthesis reaction - when two elements react to form a new compound. The reaction
takes the form of A + B  AB

              Eg. 2Mg(s) + O2 (g)  2MgO (s)        This is a synthesis reaction because two
                                                    elements react to form one new compound.
                      A+ B       AB

       2. Decomposition reaction - when a compound decomposes into two or more new

              This reaction takes the form of AB  A + B

              Eg. CH4 (g)  CO2 (g) + H2 O (g)

              Eg. H2O  H2 (g) + O2 (g)

        Evidence that you can use to prove that a chemical reaction has taken place

       You need to give as many pieces of evidence as you can to prove that a chemical reaction
has taken place. Some types of evidence are:

1.            A temperature change occurs. Temp. either increases or decreases during the
              reaction. (Like when the temperature in the test tube changed when you reacted
              copper (II) sulphate solution with steel wool - it got warmer or when you reacted
              hydrochloric acid with magnesium, the temperature increased.)
2.            Light is given off. This will usually be accompanied by heat being given off too.
3.            A change in color. (Eg. Like when you mixed two clear solutions, lead (II) nitrate
               and potassium iodide - a yellow precipitate formed or when you reacted copper
               (II) sulphate solution with steel wool - the steel wool changed into a coppery
               colored substance.)
4.             Odour changes.
5.             A change in the texture.
6.             Bubbles appear in the solution. This is evidence of gas being given off. (Eg .
               Like when you put magnesium in with hydrochloric acid or when you mixed
               hydrochloric acid and baking soda)

Seatwork assignment: ( refer to p. 27 ,28 and 29)

1.     Define mass.
2.     When Mg reacts with hydrochloric acid, what gas is given off?
3.     When gas is produced by a chemical reaction, what will happen to the gas if you don’t
       trap it?
4.     How can mass “go missing” in the products of a reaction?
5.     State the Law of Conservation of Mass.
6.     Define the term”law” as it applies to science.

Obj. 22               The Law of Conservation of Mass (P. 28 and p. 31)

        The law of conservation of mass states that a chemical reaction, the total mass of the
reactants is always equal to the mass of the products. Atoms are never created or destroyed, they
just get rearranged in a chemical reaction.

        When chemical reactions occur and you compare the mass of the reactants and products,
they may not be the same. But, this is most likely due to escaping gas or experimental error. We
performed two experiments to observe this, activity 1-7 and 1-8. In one we trapped the escaping
gas and there was no change in the mass of the products and the reactants. In the other activity,
we allowed the product gas to escape. This caused an apparent mass difference between
reactants and products. But, the Law of conservation says that there really was no difference.
The mass difference was caused by the escaping gas that we did not trap and weigh as a product.

Obj. 23                          Chemical Identification Tests

       These are tests that scientists can do to detect the presence of certain substances produced
during a chemical reaction. We will learn the chemical identification tests for detecting the
presence of:

       1. Oxygen gas
       2. Carbon dioxide gas
       3. Water
       4. Hydrogen gas
Combustion - any chemical reaction in which oxygen is a reactant and heat is produced.

Chemical Identification Test for the presence of oxygen gas - the glowing splint test:

        Light a splint of wood then blow out the flame so that is has a glowing ember on its end.
Place the glowing end into the test tube containing the “suspect” gas. If the splint bursts into
flames, the gas present is oxygen.

Chemical Identification Test for the presence of hydrogen gas - the “pop”test:

        Light a splint of wood. Place the burning end of the splint into the test tube containing
the “suspect” gas. If a loud “POP”, a mini - explosion happens, then the gas is hydrogen.

Chemical Identification Test for the presence of water:

        Use cobalt (II) chloride test paper. This paper is normally blue. When it touches water, it
turns a pink colour, telling you the substance is water.

Chemical Identification Test for the presence of carbon dioxide gas:

       Collect the “suspect” gas and then bubble it through limewater (aqueous calcium
hydroxide). Limewater is a clear, colourless solution. If the gas is carbon dioxide, it will react
with the limewater and make it go cloudy. (Makes it Look “milky”).

Obj. 24 - 26                  Acids and Bases (pages 40 - 46)

Acid - a type of compound which when dissolved in water produces an aqueous solution with a
       pH of less than 7.0

Base - a type of compound which when dissolved in water produces an aqueous solution with a
       pH of more than 7.0

***Review the pH scale on p. 43 of the text. Also, review the pH scale notes in your
Environmental Quality unit. We have already covered how the pH scale works.

Acid - Base Indicators:

        These are chemicals that can tell you, usually by a color change, that a solution is an acid
or a base.
        One example of this is the Litmus paper test. Litmus paper comes in two types, Blue and
red. To test a substance, dip the Litmus paper into it and observe the color change.

       B_R_A - if Blue litmus paper turns Red, it is an Acid.

       If red litmus turns blue, it is a base.

       If neither one of them change color, the solution is neutral, neither acid or base.

Universal Indicators:           a pH indicator. It reacts, goes through a color change, depending
                                on the strength of the acid or base. It identifies a substance as acid
                                or base AND tells you how strong it is according to the pH scale.

       One example of universal indicator is pH paper. It reacts, changing color. The color is
then compared to a color scale which tells you the pH of the solution.

Some Properties of acids and bases:

                        ACIDS                                            BASES
 has a pH of less than 7.0                          Has a pH of more than 7.0
 Turns blue litmus paper red                        turns red litmus paper blue
 will neutralize bases                              will neutralize acids
 conducts electricity                               conducts electricity
 has sour taste (eg. Vinegar)                       has bitter taste
 reacts with metals to produce hydrogen gas,        feel really slippery when dissolved in water.
 H2 (g). (Eg. we reacted hydrochloric acid          They make excellent cleaners as they can
 with magnesium metal - it gave off hydrogen        dissolve grease and oils. ( all our main
 gas)                                               household cleaners have bases in them)

 Examples of acids                                  Examples of Bases
 Vinegar - acetic acid                              Baking soda - calcium carbonate
 Orange juice - citric acid                         Drain cleaner - sodium hydroxide
 Battery acid - sulfuric acid                       Bleach - Ammonia
 Hydrochloric acid                                  Limewater - calcium hydroxide
Neutral substance -     a solution which is neither acid or base; it has a pH of exactly 7.0.

Neutralization Reaction (p. 44):

Acid                    +       Base             some type of salt + water ( pH will be close to neutral)
(pH less than 7.0)      (PH greater than 7.0)
        This happens when an acid and a base are mixed together. They react and neutralize each
other. They use each other up in the reaction, producing a solution with a pH close to neutral, pH
7.0. This reaction takes away the harmful properties of the acid and the base. A neutralization
reaction always produces two types of products: (1) some type of a “salt” and (2) water.

         Salt - a ionic compound. A metal bonded with a nonmetal.

        If a harmful acid is spilled in the lab, we pour a weak base on it to cause a neutralization
reaction so that we can safely clean it up.

Eg.      Say hydrochloric acid was spilled, I would pour sodium hydroxide, a base on it. This
         would cause neutralization. The solution left over would have a pH close to neutral, 7.0
         and be harmless.

Eg.      Hydrochloric acid + sodium hydroxide ---> sodium chloride + water

         The salt produces here is the same as table salt. We produce salt water!

Eg.      Nitric acid is spilled. I could pour some potassium hydroxide, a base, on it to neutralize

Eg.      Nitric acid + potassium hydroxide ---> potassium nitrate + water
                                              (A Salt)

Q.       If a harmful base such as sodium hydroxide was spilled, how could I safely clean it up?

A:       I could poor a weak acid, such as vinegar (acetic acid) on it to cause neutralization. I
         would keep slowly adding the vinegar until all bubbling has stopped.. At this point, I
         know that the pH level is safe. I would wear gloves and wipe up the spill with paper

         Vinegar + sodium hydroxide ---> a salt + water ( pH wiil be close to neutral)

       Your stomach produces Hydrochloric acid to help digest food. Sometimes, a person’s
stomach produces too much hydrochloric acid and this causes heartburn and upset stomach.
Antacids are weak bases that are used to neutralize the excess stomach acid which causes
heartburn. Some examples of antacids are Tums, Eno, and Rolaids.

Do the following questions: p. 55, # 1,2,3.

Obj 27 -28        Factors That Affect the Rate of a Reaction (pages 47 - 50)

Reaction rate -          the time it takes for a chemical reaction to complete.

       Three factors can affect the rate of reaction:

1.     Temperature of the reaction -            this affects the rate of all reactions. Generally, an
                                                increase in the temperature speeds up the reaction
                                                rate. A decrease in temperature slows down a
                                                reaction rate.

       Eg.        When you place Alka-seltzer (ENO) in hot water, it fizzes faster, The gas escapes
                  at a faster rate and the reaction finishes sooner than if you put it in cold water.

2.     Surface area of the reactants -          a larger surface area speeds up reactions.

       Eg.        Wood chips burn faster and give off more heat in a shorter period of time than the
                  same mass of wood burned as a log. The log burns (reacts) more slowly because
                  it has a smaller surface area exposed to the flames than the wood chips.

       DO:        Activity 1-15, p. 49.

3.     Concentration of the reactants
       concentration -      the amount of solute present in a solution.

       Concentrated solutions have more dissolved solute than dilute (weak) solutions.

       Eg.        Concentrated hydrochloric acid has more hydrogen chloride dissolved in it than
                  dilute hydrochloric acid. We saw the difference in the reaction rate in the lab.
                  Recall how your dilute hydrochloric acid reacted with the magnesium metal. It
                  bubbled a bit. When I demonstrated the reaction with the concentrated
               hydrochloric acid, there was vigorous (much more) bubbling.

Review Questions:

       pages 56 - 57. #1,2,3,4,5,7,8,10,12
       page 55        # 1,2,3
       page 39        # 1-10.
       Page 18        # 2, 4, 7.

Review activities 1-6, 1-7, 1-8, 1-14, 1-15, 1-16