Objectives (5 - 10 minutes)

1. Understand the origin and evolution of the Periodic Table:

   • Students should be able to explain how the Periodic Table evolved over time, from its origin to its current form.
   • They should understand how the elements were initially organized and what changes occurred to reach the current configuration.

2. Identify the main scientists involved in the creation and development of the Periodic Table:

   • Students should recognize the key scientists in the history of the Periodic Table and understand their specific contributions.
   • They should be able to associate each scientist with the changes they introduced in the organization of the elements.

3. Understand the importance of the Periodic Table for Chemistry:

   • Students should be able to explain how the organization of elements in the Periodic Table reflects their chemical properties.
   • They should understand how the Periodic Table is used to predict the behavior of elements and to identify new substances.

Secondary Objectives:

• Develop research and oral presentation skills:
  • Students should learn to research reliable information on a topic and be able to present this information clearly and organized to the class.
  • They should be encouraged to ask questions during research to deepen their understanding of the topic.

Introduction (10 - 15 minutes)

1. Review of previous contents:

   • The teacher should start the lesson by recalling fundamental concepts for understanding the topic, such as the concept of chemical element, atom, and its subatomic particles.
   • It is important for students to have a solid understanding of these concepts before moving on to the history of the Periodic Table.
   • The teacher can do this through quick questions, group discussions, or reviews of previous class notes.

2. Presentation of problem situations:

   • The teacher can propose two situations to arouse students' interest:
     • The first situation could be: 'Imagine you are a scientist in the 19th century and have the task of organizing the known elements so far. How would you do that?'
     • The second situation could be: 'Suppose you have discovered a new element and need to identify it. How can the Periodic Table help you in this task?'

3. Contextualization of the subject's importance:

   • The teacher should explain that the Periodic Table is one of the most important tools in Chemistry, as it organizes elements according to their chemical properties, allowing to predict the behavior of elements and identify new substances.
   • Some examples of how the Periodic Table is used in practice can be mentioned, such as in predicting chemical reactions, identifying unknown substances, and creating new materials.

4. Introduction to the topic:

   • The teacher should introduce the topic of the history of the Periodic Table, explaining that the Periodic Table did not emerge overnight but went through a long and complex development process.
   • It can be briefly mentioned that the Periodic Table went through several versions before reaching the form we know today, and that each of these versions was the result of the contributions of various scientists over time.

This Introduction aims to capture students' attention, arouse interest in the subject, and prepare them for the content that will be covered in the lesson.

Development (20 - 25 minutes)

1. The Origin of the Periodic Table (5 - 7 minutes):

   • Exploring the Pre-Table Periods (2 - 3 minutes): The teacher should explain that before the existence of the Periodic Table, elements were organized according to their chemical properties, but without the systematic ordering that the Periodic Table provides. The existence of several attempts to organize the elements, such as Dobereiner's triad and Newlands' law of octaves, can be mentioned, discussing why these attempts were insufficient.
   • Mendeleev's Contribution (2 - 3 minutes): The teacher should explain that the modern Periodic Table began with the work of Dmitri Mendeleev, who was the first to systematically organize the elements. The teacher should describe how Mendeleev arranged the elements in ascending order of atomic mass, leaving empty spaces for elements he predicted would be discovered in the future. Mendeleev's prediction of germanium and scandium, two elements that were later discovered and fit perfectly into the empty spaces he had left, can be mentioned.
   • Advancements After Mendeleev (1 - 2 minutes): The teacher should discuss how the Periodic Table evolved after Mendeleev, with the discovery of the proton and the understanding that atomic number, not atomic mass, is the property that determines an element's position in the Periodic Table.

2. The Main Scientists in the Creation of the Periodic Table (5 - 7 minutes):

   • Antoine Lavoisier (1 - 2 minutes): The teacher should present Antoine Lavoisier as the 'Father of Modern Chemistry' and explain that he was the first to propose a consistent chemical nomenclature system. It can be mentioned that Lavoisier grouped the elements into metals, non-metals, and gases, a classification still used in the modern Periodic Table.
   • Johann Wolfgang Döbereiner (1 - 2 minutes): The teacher should discuss Döbereiner's work with triads, groups of three elements that exhibit similar properties. It can be mentioned that although triads did not prove to be a generally useful organization for elements, they were important because they stimulated other scientists to look for patterns in the chemistry of elements.
   • John Newlands (1 - 2 minutes): The teacher should explain Newlands' law of octaves, which states that 'if the elements are listed in ascending order of atomic mass, then the chemical properties repeat every eight elements.' It can be discussed why the law of octaves was widely rejected at the time it was proposed, but also why it is seen today as an important precursor to the modern Periodic Table.
   • Julius Lothar Meyer (1 - 2 minutes): The teacher should describe Meyer's work, who was one of the first to organize the elements in ascending order of atomic mass. It can be mentioned that Meyer's work was independent of Mendeleev's, but Mendeleev is generally credited with the creation of the Periodic Table because he was the first to predict the existence of several elements and correctly predict the properties of these elements.

3. The Modern Periodic Table (5 - 7 minutes):

   • Organization of Elements (2 - 3 minutes): The teacher should explain how elements are organized in the modern Periodic Table, with similar elements grouped in columns called groups and elements with similar properties arranged in horizontal lines called periods. Briefly discussing the properties of elements in different groups and periods can be done.
   • The Importance of the Periodic Table (1 - 2 minutes): The teacher should revisit the importance of the Periodic Table, explaining how it is used to predict the behavior of elements and to identify new substances. It can be mentioned that the Periodic Table is used in almost all branches of chemistry, from analytical chemistry to inorganic and organic chemistry, and that it is one of the most important tools that chemists have at their disposal.
   • The Future of the Periodic Table (1 - 2 minutes): The teacher should briefly discuss the future of the Periodic Table, explaining that new elements are continuously being discovered and that the position of these elements in the Periodic Table is not yet fully known. It can be mentioned that scientists are working to fill the empty spaces in the Periodic Table with new elements and that this will continue to be an important research topic in chemistry in the coming years.

This Development aims to provide students with a clear and detailed understanding of the history of the Periodic Table, from its origin to its current form. Throughout this section, students will be encouraged to ask questions and actively participate in the discussion to deepen their understanding of the topic.

Return (10 - 15 minutes)

1. Group Discussion (5 - 7 minutes):

   • The teacher should divide the class into small groups and ask them to discuss the main information they learned during the lesson.
   • Each group should choose a spokesperson to share their conclusions with the class.
   • The teacher should circulate around the room, listening to the group discussions and providing feedback and clarifications as needed.

2. Connection with Theory (3 - 5 minutes):

   • The teacher should ask students to reflect on how the lesson connects with the real world and with other concepts they have learned in Chemistry.
   • For example, it can be asked how the history of the Periodic Table relates to atomic structure or the periodic properties of elements.
   • Students can also be asked to think about everyday situations where the Periodic Table is used, such as in predicting chemical reactions or identifying unknown substances.

3. Individual Reflection (2 - 3 minutes):

   • The teacher should propose that students reflect individually on what they learned in the lesson.
   • Questions like 'What was the most important concept you learned today?' and 'What questions have not been answered yet?' can be asked.
   • The teacher should encourage students to be honest in their reflections and to express any doubts or insecurities they may still have.

4. Sharing Reflections (2 - 3 minutes):

   • The teacher should ask some students to share their reflections with the class.
   • This can help identify any gaps in students' understanding and provide an opportunity to clarify any misunderstandings or confusions.

This Return aims to consolidate students' learning, allowing them to reflect on what they have learned and how it applies to the real world. It also provides the teacher with valuable feedback on the effectiveness of the lesson and areas that may need review or reinforcement in future classes.

Conclusion (5 - 10 minutes)

1. Summary and Recapitulation (2 - 3 minutes):

   • The teacher should recap the main points discussed during the lesson, reinforcing the importance of the Periodic Table in Chemistry and how it has evolved over time.
   • The origin and evolution of the Periodic Table, the main scientists involved in its creation and development, and the organization of elements in the modern Periodic Table can be reviewed.
   • The teacher should highlight how the Periodic Table reflects the chemical properties of elements and how it is used to predict the behavior of elements and to identify new substances.

2. Connection between Theory, Practice, and Applications (2 - 3 minutes):

   • The teacher should emphasize how the lesson connected theory (the history of the Periodic Table and the organization of elements) with practice (discussing the contributions of scientists and analyzing the properties of elements) and applications (the importance of the Periodic Table in Chemistry and how it is used in practice).
   • Specific examples of how the Periodic Table is used in practice, such as in predicting chemical reactions, identifying unknown substances, and creating new materials, can be mentioned.
   • The teacher can also reiterate the importance of understanding the Periodic Table for students who wish to pursue careers in sciences, medicine, engineering, and other related fields.

3. Extra Materials (1 - 2 minutes):

   • The teacher should suggest extra materials for students who want to deepen their understanding of the topic.
   • Books, websites, videos, and interactive apps that explore the history of the Periodic Table in more depth can be recommended.
   • Practical activities, such as conducting experiments with elements from the Periodic Table or creating three-dimensional models of the Periodic Table, can also be suggested.

4. Relevance of the Topic (1 - 2 minutes):

   • Finally, the teacher should emphasize the importance of the Periodic Table in everyday life.
   • It can be mentioned that the Periodic Table is not only a tool for scientists but also for the general public, as it is used in various practical applications, such as in drug production, construction material manufacturing, energy generation, among others.
   • The teacher can end the lesson by reinforcing that the Periodic Table, despite its apparent complexity, is actually a powerful and accessible tool that helps us understand and manipulate the world around us.

The Conclusion aims to consolidate students' learning, provide an overview of the topic, and connect theory with practice and applications. Additionally, it offers students the opportunity to continue learning about the Periodic Table autonomously and to apply what they have learned in their daily lives and future careers.