Activity Sheet: Periodic Law

1. Introduction to the periodic table

To stimulate discussion and introduce the periodic table, distribute a simple periodic table that has the groups and the names of the elements labeled.

Get students to:

A. Use a red colored pencil to lightly shade any metals that they know.

B. Use a blue colored pencil to lightly shade any nonmetal that they know.

Through student discussion establish that the periodic table is divided into groups (I-VIII) and periods. At this stage, some of the common names of the groups could be given to students--e.g., alkali metals (group I), alkaline earth metals (II), halogens (VII), and noble gases (VIII).

D. Discuss with students the universal nature of the periodic table and the naming of

chemical elements. What is the advantage of this to scientists all over the world?

E. Have students try to complete any of the following so as to familiarize themselves

with the periodic table. These questions could be assigned as research or homework problems. Some answers are indicated in brackets.

In which part of the periodic table (group and period) would you find the following:

§ the most reactive metal [Francium Z = 87]

§ the most reactive nonmetal [Fluorine Z = 9]

§ a group of unreactive gases [group VIII noble gases]

§ metals that form colored compounds [d-block, transition metals]

§ elements that form diatomic molecules [group VII halogens]

§ elements that form positive ions

§ elements that form negative ions

2. Teacher led discussion/student research--Mendeleyev's discovery then and now

In this activity students are to compare the periodic table as first developed by Dmitry Mendeleyev compared to a modern periodic table.

Start by referring to a modern periodic table and quizzing students as to what the table shows and what information can be obtained from it.

Inform students that the periodic table has evolved over many years. The first version of the periodic table was written in 1869. Show students a copy of the first version of the periodic table.

Students should work on the discussion questions below in small groups using resources found at Britannica School or library resources. Students should then gather as a larger group to discuss the answers to the questions below.

A. How many elements did Mendeleyev know existed when he wrote his first periodic table?

B. Visit the following site and compare this number of elements with the number of elements in a modern periodic table. http://new.britannicaschool.com/ebsearch/art.asp?id=592&typeID=A How many chemical elements remained undiscovered when Mendeleyev wrote his first periodic table?

C. Which group of elements is absent from the original version of the periodic table? Why do you think this might be?

D. Make a list that shows the similarities and differences between Mendeleyev's original table and the modern periodic table.

3. Student research: Dmitry Mendeleyev

Students are to research the work of Dmitry Mendeleyev in more detail. The questions below can be used as a basis for this research. Students will need access to a variety of research materials including the Internet.

A. It is not uncommon in science to have several scientists working on a similar area. Were there any other scientists working on a similar table at the same time as Mendeleyev? If so, describe who they were and their contribution to the development of the periodic table.

In order to illustrate the usefulness of his periodic table, Mendeleyev wrote some descriptions of properties of elements of then undiscovered chemical elements. He named one of these undiscovered elements “Ekasilicon.” What were the predicted properties of Ekasilicon? What chemical element was discovered that had the properties of Ekasilicon? How close were the properties of Ekasilicon to the actual element?

4. Student activity: Other ways of representing chemical elements

In this activity students can explore some alternative ways of representing chemical elements to illustrate the usefulness of the periodic table.

Students will need a copy of the periodic table that they can cut up to complete this activity.

Representing elements by letter

Cut out all of the elements from the periodic table. Arrange these in rows alphabetically. Some sample rows are shown below:

After students have completed this task discuss the following:

· Would this be a good way of representing the chemical elements? Explain your answer and discuss this with the whole class.

· Even though the structure above is not useful, there are some other ways of representing the periodic table. These can be explored through the following links to Encyclopædia Britannica:

http://www.britannicaschool.com/ebsearch/art.asp?id=590&typeID=A

http://www.britannicaschool.com/ebsearch/art.asp?id=591&typeID=A

§ Can you determine some other ways of showing the chemical elements?

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