Beacon Lesson Plan Library

Metals or Nonmetals? The Families of Elements

Stewart Tick

Description

After viewing a short demonstration by the teacher, students will work cooperatively in groups to compile information on the characteristics of groups of elements. They will then present their findings to the entire class.

Objectives

The student knows that elements are arranged into groups and families based on similarities in electron structure and that their physical and chemical properties can be predicted.

Materials

-Source of water (softened tap water or distilled water, not hard water)
-One 600 ml beaker
-Four 250 ml beakers
-Plastic spoons (for stirring to dissolve the compounds in water)
-Sodium carbonate
-Lithium chloride
-Potassium chloride
-Strontium chloride
-Calcium chloride
-Student group checklist (see Associated File)
-Pre and Post Test, sufficient for the entire class (see Associated File)
-Copies of Periodic Table (sufficient for the entire class)
-Copies of Student Periodic Table Worksheet, sufficient for the entire class (see Associated File)
-Transparencies, poster paper, and markers, in case students wish to use them to help make their class presentations.

Preparations

Prior to class meeting:

1. Add 500 ml of water to a 600 ml beaker. Dissolve two teaspoons of sodium carbonate in the
water. Use a plastic spoon to do the measuring and stirring to dissolve the chemical.

2. Add 200 ml of water to a 250 ml beaker. Dissolve one teaspoon of potassium chloride in the
water using a plastic spoon to stir the solution. Label this beaker Number One.

3. Add 200 ml of water to a 250 ml beaker. Dissolve one teaspoon of lithium chloride in the
water using a plastic spoon to stir the solution. Label this beaker Number Two.

4. Add 200 ml of water to a 250 ml beaker. Dissolve one teaspoon of calcium chloride in the
water using a plastic spoon to stir the solution. Label this beaker Number Three.

5. Add 200 ml of water to a 250 ml beaker. Dissolve one teaspoon of strontium chloride in
the water. Label this beaker Number Four.

6. Prepare enough copies of the periodic table, Student Periodic Table Worksheets, and the
Pre and Post Test for the entire class.

7. Have transparencies, poster paper, and markers available, in case students wish to use them to help make their class presentations.

Procedures

1. Give Pre-Test to the entire class.

2. Briefly review the definitions of elements and compounds and the parts of the atom ( which should have been presented earlier). The students need to be familiar with this prior
knowledge before beginning this lesson.

3.. From the 600 ml beaker, pour approximately 100 ml of sodium carbonate solution into each of the labeled 250 ml beakers in succession. The first two beakers will not show any color change, but the last two will change from clear to a milky white color. Ask students what these indicate about the properties of lithium and potassium as compared to those of calcium and strontium. Ask the students to locate these four elements on the periodic table. Use the student responses to introduce the concept of groups or families of elements with similar properties.
4. Discuss the locations of the families on the periodic table and relate these to the electron configurations (specifically, the number of valence electrons). Be sure to include the following points:
A. Group 1, the Alkali Metals, have one valence electron, and are the reactive metals.

B. Group 2, the Alkaline Earth Metals, have two valence electrons, and are the second most reactive metals.

C. Group 17, the Halogens, have seven valence electrons, and are the most reactive nonmetals.

D. Group 18, the Noble Gases, have eight valence electrons, and are the most unreactive of all elements.

E. The Lanthanoids and Actinoids, collectively known as the Rare Earth Metals, are found at the bottom of the periodic table.They generally have two valence electrons.

F. Metals usually have one to three valence electrons. They are solids at room temperature (with the exception of mercury) and have high density and conductivity. They are also malleable and ductile and have luster.

G. Nonmetals usually have five to eight valence electrons. They may be solid, liquid, or gas at room temperature. Their properties are the opposite of those of metals.

5. Divide the class into five groups: Alkali Metals, Alkaline Earth Metals, Halogens, Noble Gases, and Rare Earth Metals. Within each group, each student will be assigned one element to research. (In the smaller families, two students may be assigned to research the same element.) The following information must be found regarding each element:

A. Name and Symbol
B. Atomic Number
C. Atomic Mass
D. Number of Valence Electrons
E. Metal or Nonmetal
F. Representative physical properties
G. Representative chemical properties

This information can be found in many physical science reference books, including the following:

Chemical Elements: From Carbon to Krypton, Vols. 1-3. Newton, David E.,
UXL, Farmington Hills, Michigan, 1999

CRC Handbook of Chemistry and Physics, 81st ed. Lide, David R., ed.,
CRC Press, New York, 2000

Concise Encyclopedia of Chemistry. Eagleson, Mary, Wlater de Gruyter,
New York, 1994

The Elements, 3rd ed. Emsley, John. Oxford University Press, Oxford, UK,
1998

The Facts On File Dictionary of Chemistry, 3rd ed. Daintith, John, ed.
Facts On File, Inc., New York, 1999

The History and Use of Our Earthís Chemical Elements: A Reference
Guide. Krebs, Robert E., Greenwood Press, Westport, Connecticut, 1998

The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals,
12th ed. Budavari, Susan, ed. Merck & Co., Inc., Whitehouse Station
New Jersey, 1996

6. Members of each student group will compile the information regarding the elements, and select two spokespersons to present their findings to the entire class. If desired, the student groups may use charts, drawings, diagrams, transparencies, or other visual aids to help make their presentation. Each student group will be required to demonstrate an understanding of the following points:

A. Elements in the same group have a similar number of valence electrons.
B. Elements in the same group therefore have similar chemical and physical properties.
C. Metals are located on the left side and in the center of the periodic table. Nonmetals are found on the right side of the periodic table.

7. Assign Student Periodic Table Worksheet as a homework assignment for the next class period.

8. Review answers to the Student Worksheets with the class at the beginning of the next class period.

8. Give Post Test to the entire class.

9. On the basis of the results of the Post Test, the instructor may decide which concepts may require reteaching.

Assessments

Each student will be given a Pre and Post Test (see Associated File). Each student group presentation will graded by means of a checklist (see Associated File).

Extensions

For extension, have students relate each elementís number of electron energy levels and the charge of its ion(s) to its position on the periodic table. They should realize that the number of electron energy levels is equal to the period number, and the charge of the ion is related to the number of its group or family.

Web Links

These websites all contain copies of the periodic table, with information about each element provided by clicking on the appropriate square on the table. The first site (Chemical Elements) provides the most useful information for this lesson.
Chemical Elements

These websites all contain copies of the periodic table, with information about each element provided by clicking on the appropriate square on the table. The first site (Chemical Elements) provides the most useful information for this lesson.
Web Elements

These websites all contain copies of the periodic table, with information about each element provided by clicking on the appropriate square on the table. The first site (Chemical Elements) provides the most useful information for this lesson.
MIT

These websites all contain copies of the periodic table, with information about each element provided by clicking on the appropriate square on the table. The first site (Chemical Elements) provides the most useful information for this lesson.
Los Alamos National Labs

Attached Files

Attached document.     File Extension: pdf

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