Unit Two: Periodic classification of the Elements

Lesson 4: Periodic Properties

• Comptencies
• Starter Activities
• Main Activites

Competencies 

Less 4: Project work on the periodic table (Individual Task)

Competencies:

To enable the students to:

• Describe the advantages of the periodic classification of the elements in the study of chemistry.
• Appreciate the classification of elements done by different scientists.
• Describe the most important features of each classification.
• Discuss the changes in methods of classification with time.

Materials

Periodic table chart

Starter activity (15 minutes)

Let the students revise the previous lessons on periodic table by raising all the contents from early attempts of classification to the trends in properties of the elements. This can be done by asking leading questions like:

• What were the historical attempts of classification of the elements? What are their similarities?
• How does the Mendeleev’s classification differ from the other earlier classifications?
• What are the differences between the Mendeleev’s and the modern periodic laws?
• How many blocks does the modern periodic table have? What is the basis for these blocks?
• How many groups and periods are there in the modern periodic table? What are the specific features of each period and group?
• How do you determine the period and the group numbers of an element if its atomic number is given?
• How is the electronic configuration of atom of an element related to its location in the periodic table?
• Which properties of the elements change in the period of the periodic table? How and why?
• Which properties of the elements change in the group of the periodic table? How and why?

Make sure that all students have participated in the revision discussion and have grasped the concepts.

Evaluation

Give atomic numbers of some elements and ask them to

• Determine period and group numbers.
• Number of shells and valence electrons
• Decide whether they are metals or non-metals
• Predict their properties like ionization energy, electron affinity etc.

Now you can provide the following project work.

Procedure:

1. You may write the procedure on the chalk board. Let the students understand it clearly and submit their work in a week time.
2. You may provide lists of reference books available in the library
3. The Students may be asked to collect the information and prepare a written report of the project using the format given below of Elements For Teachers
   • Objectives of the Project- why they are doing the project.
   •  Introduction – some information about their works.
   • Material required (if any) – this may be any material they used during their project work.
   • Procedure – stapes they followed in their work.
   • Presentation of the Information / Data Collected.
   • Conclusion.
   • Reference used

Collect the students work, check and categorize in to three: the best, medium and poor performance (you may do it based on your convenience). You may allow one student from each category to present the group work for five minutes.

When you analyze the project and the presentation, you may encounter the following conditions.

A few students may have not been able to collect information from different sources or may have written the whole content from the text book; or students may have been motivated to search material from different sources.

A Few students may have not been able to analyze the data collected and understand the merits and demerits of different classification of elements. So, you may help the students understand the significance of classifying the element in periods and groups.

After the completion of the project, you may give the detailed information about the periodic classification of elements, involving them in the lesson, using question and answer techniques.