Summer Research Program for Science Teachers

Hoa Tu

Baruch College Campus H.S., Manhattan

2000

 

Chemistry Unit on Compounds, Formulas and Equations

PART 1 - REVIEW

NAMING IONIC COMPOUNDS:

In naming ionic compounds, we must remember that the total charge for the cation and anion must equal to zero (0).  The cation always comes first in the compound, it has a positive charge.  The anion always comes after the cation in the compound, it has a negative charge.  [9-12 Content Standard B- Properties of matter]

What are the names for the following ionic compounds?  [Content Standard Unifying Concepts- Order and organization]

1.     CaO _____________________________________

2.     NiPO4 ______________________________________________________

3.     Fe(OH)2 ____________________________________________________

4.     NiO ______________________________________

5.     NaOH ____________________________________

6.     Al2S3 ________________________________________________________

7.     CuO ______________________________________

8.     CoPO4 _______________________________________________________

9.     Fe(NO3)2 ____________________________________________________

10. NaHCO3 ____________________________________________________

11. Co(C2H3O2)3 _______________________________________________

12. NiP _______________________________________

 

NAMING MOLECULAR COMPOUNDS:

Molecular compounds are  made of atoms bonded together by sharing electrons. [9-12 Content Standard B- Structure of matter]  They are different from ionic compounds in that there are no ions and no charge involved.  When we name any molecular compound, what we need to do is to find the name of each element in the compound and to know the prefixes for the total number of each element in the compound.

What is the name for the following molecular compound?

1.     NaF4 _____________________________________________

2.     SiCl6 _____________________________________________

3.     Br3O7 ____________________________________________

4.     NF4 ______________________________________________

5.     P3Br9 _____________________________________________

6.     Ag3O8 _____________________________________________

7.     C4Cl3(OH)7 _________________________________________

8.     Na(OH)3F2 __________________________________________

9.     C2(OH)10Br4 _________________________________________

10. Rb5As(H2O)5 _________________________________________

11. Fr2C5(OH)2 ___________________________________________

12. SrCr6(NO3)3 ___________________________________________

  

DRAWING THE SHAPES OF COMPOUNDS:

Most molecules we find in things around us are not flat in shape, they are three dimensional.  We have talked about 9 different molecular shapes.  We know how to construct these shapes using the ball-and-stick model or draw the shapes using only the periodic table to find the valence electrons of the elements.

Draw and name the shape for the following molecules.  [9-12 Content Standard B- Structure of matter]

1.  CH4

7.  K2O

2.  CO2

8.  NF5

3.  PLi

9.  GaI3

4.  N2

10  BrK3

5.  ArI4

11.  RnF4

6.  TeF6

12.  PbH4

 

WRITING CHEMICAL FORMULAS:

When we are given the name of a compound and asked to write its formula, there are 2 things we need to keep in mind.  First, the number of the prefix is written as a subscript after the element.  Second, the total charge of an ionic compound must equal zero (0).

What is the formula for the following compound?

1.     copper nitrate ________________________________________________

2.     copper(II) hydroxide ___________________________________________

3.     calcium chloride ______________________________________________

4.     tri-bromo-tri-hydroxide __________________________________________

5.     penta-carbo-deca-hydrogen-deca-oxide ______________________________

6.     potassium acetate _______________________________________________

7.     zinc(II) chloride ________________________________________________

8.     nickel(III) nitrate _______________________________________________

9.     magnesium oxide _______________________________________________

10. aluminum sulfide _______________________________________________

11. sodium phosphide ______________________________________________

12. iron(III) chloride _______________________________________________

 

BALANCING CHEMICAL EQUATIONS: [Content Standard Unifying Concepts- Change, constancy, and measurement]

To have a balanced equation, we need to make sure that the total number of each element on the reactant side is equal to the total number on the product side.  We can only put numbers (coefficient) before a single element or a whole compound to help balance the equation.  We can not balance the equation by putting the number after an element.  There are 5 steps to follow when balancing an equation.

STEP 1  Write the word equation for the reaction.

STEP 2  Write the formula equation for the word equation.

STEP 3  Count the number of atoms of each element on both sides of the equation. 

    Use coefficients to help balance each element.

STEP 4  Count the number of atoms of each element to make sure that the number is

    the same on both sides of the equation.

STEP 5  Rewrite the balanced equation.

 

Balance the following reaction.

1.     Potassium nitrate reacts with heat to produce potassium nitrite (HNO2) and oxygen gas (O2).

2.     Iron reacts with sulfuric acid (H2SO4) to form iron(II)sulfate and hydrogen gas (H2).

3.     Hydrogen peroxide (H2O2) reacts with light to form water and oxygen gas (O2).

4.     Potassium chlorate (KClO3) reacts with heat to produce oxygen gas (O2) and potassium chloride (KCl).

5.     Ethane (C2H6) reacts with oxygen gas to form carbon dioxide and water.

6.     Ammonia (HN4) reacts with oxygen gas to form nitric oxide (NO) and water.

7.     Aluminum reacts with oxygen gas to form aluminum oxide.


PART 2 - PROJECT

WHAT TO DO:

1.     Each pair of students will be randomly assigned a chemical reaction.

2.     Write the word equation for the reaction.

3.     Write the formula equation for the reaction.

4.     Write the balanced equation for the reaction.  Show all your work.

5.     Make a model of your reaction using the ball-and-stick method.  We will make balls out of clay and use toothpicks for the sticks.  [Content Standard Unifying Concepts- Models and explanation]

6.     Draw and name the shape of every compound in your reaction.

 

Example,

Reaction:      Oxygen gas reacts with hydrogen gas to produce water.

Word equation:      oxygen gas   +   hydrogen gas   ®   water

Formula equation:      O2      +      H2      ®      H2O

Balanced equation:      ½ O2      +      H2      ®      H2O

Molecular model:

Shape and name:

  

                  linear              linear              bent

 

 PART 3 - PRESENTATION

WHAT TO DO:

1.     Tape your model to a cardboard.

2.     Write the balanced equation beneath the model.

3.     Create a flow chart to show how you went about doing this project. 

 Example,

 

            Read the reaction          ®              write the word equation

                                                                        ¯

Find the symbols for each

element in the reaction

¯

                                                                  write the formula equation

                                                                        ¯

                                                                  make sure the charge for

If no                        ¬                        all the compound is zero (0)

¯                                                            ¯

balance the charge by…                            If yes

                                                                        ¯

                                                                        and so on…

 

PART 3 - PRESENTATION

WHAT TO DO:

1.     Tape your model to a cardboard.

2.     Write the balanced equation beneath the model.

3.     Write a short essay (1 page) on how you went about to complete this project.  Talk about what you knew before you started the project, then talk about what new things you have learned after completing the project.  You need to make sure that you checked your spelling, punctuation and capitalizing.  Points will be taken off for each mistake found in your essay.

4.     You may want to include pictures or diagrams to help explain your essay.

5.     Attach your final essay onto the cardboard, as part of your presentation.

 

PART 3 - PRESENTATION

WHAT TO DO:

1.     Tape your model to a cardboard.

2.     Write the balanced equation beneath the model.

3.   Research  the usage of the product in your reaction.  [9-12 Content Standard E- Understandings about science and technology]

A.  What kind of materials can you find the compound? 

B.    How and why is the compound used in that material?

4.     Include a sample of  the material in your presentation.  Tape it to your cardboard.

5.     Your final paper should also be attached to your cardboard as part of your presentation.

 

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