Lesson Plan | Active Learning | Atoms: Atomic Mass Unit

Assumptions: This Active Lesson Plan assumes: a 100-minute class, prior student study with both the Book and the start of Project development, and that only one activity (among the three suggested) will be chosen to be conducted during the class, as each activity is designed to take up a significant portion of the available time.

Objectives

Duration: (5 - 10 minutes)

The Objectives stage is crucial to establish the focus of the lesson and ensure that both the teacher and the students are aligned regarding the expected outcomes. In this section, the main objectives are outlined to guide subsequent activities, ensuring that students can not only understand the theoretical concepts related to atomic mass unit but also apply them in practical contexts. This approach aims to maximize learning effectiveness, allowing students to actively engage during classroom activities.

Main Objectives:

1. Enable students to understand and define the concept of atomic mass, identifying its importance in Chemistry.

2. Develop mathematical skills in students so that they can calculate the atomic mass of elements, including the determination of the average mass in cases of multiple isotopes.

Side Objectives:

1. Encourage critical thinking and the application of prior knowledge in solving practical Chemistry problems.

Introduction

Duration: (15 - 20 minutes)

The Introduction stage serves to engage students and connect the content they have previously studied with practical and historical applications. By presenting problem situations, the teacher encourages students to apply their knowledge critically and practically, laying the groundwork for more complex activities. The contextualization, in turn, shows the relevance of the theme in the real world, increasing interest and awareness of the importance of studying atomic mass.

Problem-Based Situations

1. Imagine you are a chemist working in a laboratory and need to calculate the exact amount of each carbon isotope in an unknown sample. How can the atomic mass unit assist you in this calculation?

2. Suppose you are in a scientific competition and the task is to determine the atomic mass of a newly discovered element. The element has three known isotopes, each with its isotopic abundances. How would you calculate the atomic mass of this new element?

Contextualization

Understanding atomic mass is essential not only in laboratories but also in various technological and industrial applications, such as carbon-14 dating and nuclear medicine. Interestingly, the discovery and evolution of the concept of atomic mass are intrinsically linked to the history of Chemistry and Dalton's atomic theory. For example, the first periodic table, developed by Mendeleev, was organized based on the atomic masses of the elements, which helped predict the properties of elements that had not yet been discovered at the time.

Development

Duration: (75 - 80 minutes)

The Development stage is designed to allow students to practically and interactively apply the concepts of atomic mass and average mass calculation learned previously. By working in groups, students can discuss and collaborate to solve complex problems, which not only reinforces individual learning but also promotes social skills and teamwork. Each proposed activity aims to solidify students' theoretical understanding through practical applications that simulate real situations, thus ensuring significant and lasting learning.

Activity Suggestions

It is recommended to carry out only one of the suggested activities

Activity 1 - The Mystery of Element X

> Duration: (60 - 70 minutes)

- Objective: Apply the concept of atomic mass and calculate the mean mass in a practical scenario with multiple isotopes.

- Description: Students will be divided into groups of up to five members, and each group will receive an envelope containing cards with information about a fictional element, 'Element X'. These cards will include details about the isotopes of 'X', their atomic masses, and respective isotopic abundances. Based on this data, students will calculate the average atomic mass of Element X.

- Instructions:

• Form groups of up to five students.

• Distribute an envelope to each group containing the information cards about Element X.

• Ask each group to calculate the average atomic mass of Element X using the information provided on the cards.

• Each group should present their calculations and justify the method used.

• Conduct a class discussion to compare the different methods and results obtained by the groups.

Activity 2 - Isotope Treasure Hunt

> Duration: (60 - 70 minutes)

- Objective: Develop practical skills in data collection and calculation of average atomic mass.

- Description: In this playful activity, students will have to 'hunt' isotopes in various materials present in the classroom. Each material will have a label with the information of an isotope and its isotopic abundance. Students must collect this information and then calculate the average atomic mass of the isotope found in each material.

- Instructions:

• Divide the class into groups of up to five students.

• Distribute a map indicating where the different materials are hidden.

• Each group must collect information from at least five different isotopes.

• Using the collected information, the groups must calculate the average atomic mass of each isotope.

• Each group prepares a final report with the calculations and presents it to the class.

Activity 3 - Isotope Festival

> Duration: (60 - 70 minutes)

- Objective: Promote understanding of isotopes and the importance of atomic mass, as well as develop communication and research skills.

- Description: Students will organize a 'festival' where each group represents a chemical element. They will need to create explanatory posters about the isotopes of that element, their atomic masses, and isotopic abundances. Additionally, they must prepare a presentation explaining how atomic mass is determined and its importance in various applications.

- Instructions:

• Organize the class into groups of up to five students, each responsible for a different chemical element.

• Provide materials such as poster boards, markers, and access to computers and the internet for research.

• Groups must create informative posters and prepare a presentation about the element and its isotopes.

• Each group presents their poster and explains the content to the class.

• At the end, promote a vote to elect the group that best explained the concept of atomic mass.

Feedback

Duration: (15 - 20 minutes)

The purpose of this feedback stage is to consolidate students' learning, allowing them to reflect on what they have learned and share their experiences. This discussion helps reinforce the understanding of atomic mass concepts and average mass calculation, as well as promote communication and argumentation skills. By answering key questions, students have the opportunity to verbalize and review the knowledge acquired, ensuring a deeper and more lasting understanding of the topic.

Group Discussion

After the completion of the activities, gather all students for a group discussion. Start the discussion with a brief introduction, recalling the lesson's objectives and the importance of understanding atomic mass. Ask each group to share their findings and the methods used to calculate the average atomic mass. Encourage students to discuss challenges encountered and how they overcame them. Use this moment for groups to learn from each other, exchanging experiences and approaches.

Key Questions

1. What were the main difficulties you encountered when calculating the average atomic mass and how did you overcome them?

2. How can the understanding of atomic mass be applied in practical situations in everyday life or other subjects?

3. What are the implications of different isotopes in determining the atomic mass of an element?

Conclusion

Duration: (5 - 10 minutes)

The Conclusion stage is essential to consolidate learning, ensuring that students can reflect on the content learned and recognize the practical and theoretical importance of the topic. Summarizing key concepts, connecting theory with practice, and highlighting the applicability of knowledge are fundamental steps for students to internalize the content and perceive its utility in the real world.

Summary

In conclusion, the teacher should summarize the concepts discussed about atomic mass and its application in determining the average mass of elements with multiple isotopes. Recap the calculation methods and the main formulas used, emphasizing the practices carried out during the lesson.

Theory Connection

Explain how today's lesson connected theory with practice through interactive activities, such as calculating the average atomic mass of 'Element X' and the 'Isotope Treasure Hunt'. Highlight how these practices helped solidify theoretical understanding and the importance of the atomic mass concept in real-world situations and other subjects.

Closing

Finally, highlight the relevance of studying atomic mass in everyday life, such as in nuclear medicine, carbon-14 dating, and industry. Emphasize how understanding atomic mass is crucial for various technological and scientific applications, and is fundamental in the development of Chemistry as a whole.