Objectives (5-7 minutes)

1. Understand the nomenclature of aliphatic hydrocarbons: Students should be able to correctly identify and name aliphatic hydrocarbons, including alkanes, alkenes, and alkynes. They should understand the structure of these molecules and how to name them according to IUPAC rules.

2. Identify and name isomers: Students need to learn how to identify isomers, which are compounds with the same molecular formula but different structures. They should be able to name each isomer according to IUPAC nomenclature.

3. Solve practical exercises: Students should be able to apply the knowledge acquired to solve practical exercises. This includes both identifying and naming aliphatic hydrocarbons and isomers, as well as solving problems of composition and decomposition of formulas.

Secondary objectives:

• Stimulate critical thinking: In addition to simply memorizing the rules of nomenclature, students should be encouraged to understand the reasoning behind them. This will help them apply these rules more effectively and solve problems that require a deeper understanding of the topic.

• Encourage active participation: Through conducting discussions in the classroom, the teacher should encourage students to participate actively, asking questions, sharing ideas and solutions, and explaining concepts to each other. This will help to solidify the students' understanding of the topic and develop their communication and collaboration skills.

Introduction (10-12 minutes)

1. Review of Previous Concepts: The teacher should begin the class by reviewing the concepts of open, closed, saturated, and unsaturated carbon chains, which were addressed in previous classes. This will serve as a solid foundation for the introduction of the nomenclature of aliphatic hydrocarbons. (3-5 minutes)

2. Problem Situation: The teacher can propose two problem situations to arouse the students' interest:

   • Situation 1: "Imagine that you are scientists who have just discovered a new substance in nature. You need to name it according to IUPAC rules. How would you do it?"

   • Situation 2: "You have received two samples of chemical compounds, both with the same molecular formula but with different structures. How could you identify and name each of these samples?" (2-3 minutes)

3. Contextualization: The teacher should then contextualize the importance of the nomenclature of aliphatic hydrocarbons, explaining that the correct identification and naming of organic compounds is essential in diverse areas, such as medicine, pharmacy, the food industry, among others. (2-3 minutes)

4. Captivating the Students' Attention: To arouse the students' curiosity and gain their attention, the teacher can share two interesting facts:

   • Interesting fact 1: "Did you know that IUPAC, the organization responsible for chemical nomenclature, has such strict rules that they can even name the most complex compounds, such as Titin, the largest known protein, which has 189,819 letters?"

   • Interesting fact 2: "Have you ever heard of isomers? They are compounds that have the same molecular formula but different structures. They can have completely different properties, and can be harmless or even toxic. Therefore, the correct identification and naming of these compounds is essential for the safety and effectiveness of various products." (3-4 minutes)

Development (20-25 minutes)

1. Theory: Nomenclature of Aliphatic Hydrocarbons (10-12 minutes)

   1.1. Alkanes: The teacher should begin by explaining the nomenclature of alkanes, hydrocarbons that have only single bonds between the carbon atoms. It should be emphasized that the IUPAC nomenclature of alkanes is based on the number of carbon atoms in the main chain, followed by the suffix "-ane". Examples of alkane names should be shown, such as methane, ethane, propane, butane, pentane, etc. (2-3 minutes)

   1.2. Alkenes and Alkynes: Next, the teacher should introduce the nomenclature of alkenes and alkynes, hydrocarbons that have at least one double bond (alkenes) or triple bond (alkynes) between the carbon atoms. The suffix "-ene" is used for alkenes and the suffix "-yne" is used for alkynes. Again, examples should be shown, such as ethene, propene, butene (for alkenes) and ethyne, propyne, butyne (for alkynes). (2-3 minutes)

   1.3. Branched Groups: Next, the teacher should explain how to name aliphatic hydrocarbons that have branched groups. It should be emphasized that branched groups are called substituents and should be numbered so that the smallest possible numbering is given to the substitution. Examples should be shown, such as 2-methylbutane, which has a methyl group (one carbon with three hydrogens) in position 2 of the butane chain. (3-4 minutes)

2. Practice: Nomenclature Exercises (10-13 minutes)

   2.1. Group Exercises: Students should be divided into groups and each group should receive a series of hydrocarbons to name according to IUPAC rules. The teacher should circulate around the room, helping and correcting the groups as necessary. (5-7 minutes)

   2.2. Classroom Discussion: After solving the exercises, the teacher should lead a classroom discussion, asking each group to share their answers and explain the reasoning behind them. This will help to clarify any questions and solidify the students' understanding of the topic. (5-6 minutes)

3. Theory: Isomers (5-7 minutes)

   3.1. Definition and Examples: The teacher should introduce the concept of isomers, explaining that they are compounds with the same molecular formula but different structures. Examples of pairs of isomers should be shown, such as propanal and propanone, which have the same molecular formula (C3H6O) but different structures and properties. (2-3 minutes)

   3.2. Isomer Nomenclature: The teacher should then explain that each isomer must be named separately, according to IUPAC rules. Examples of isomer naming should be shown, with emphasis on the importance of identifying the main chain and giving the smallest possible numbering to the substituent groups. (2-3 minutes)

4. Practice: Exercises with Isomers (5-7 minutes)

   4.1. Group Exercises: Groups should receive a series of pairs of isomers to identify and name. The teacher should circulate around the room, helping and correcting the groups as necessary. (3-4 minutes)

   4.2. Classroom Discussion: After solving the exercises, the teacher should lead a classroom discussion, asking each group to share their answers and explain the reasoning behind them. This will help to clarify any questions and solidify the students' understanding of the topic. (2-3 minutes)

Reinforcement (8-10 minutes)

1. Content Review (3-4 minutes): The teacher should begin the Reinforcement with a brief review of the main contents covered in the class. He can ask specific questions to the students to check their understanding about the nomenclature of aliphatic hydrocarbons and the identification and naming of isomers. Furthermore, the teacher should recall the problem situations proposed at the beginning of the class and compare the solutions proposed by the students with the correct approach, highlighting the correct answers and correcting possible errors.

2. Connection with the Theory (2-3 minutes): Next, the teacher should explain how the practice done by the students during the class connects with the theory presented. He can highlight, for example, that the correct identification and naming of chemical compounds depends on the understanding of the nomenclature rules and on the ability to distinguish isomers.

3. Practical Application (2-3 minutes): The teacher should then promote a discussion about the practical application of the concepts learned. He can ask the students how they imagine that the nomenclature of aliphatic hydrocarbons and the identification of isomers can be useful in their everyday lives or in their future careers. Furthermore, the teacher can share real examples of how these concepts are applied in different areas, such as the pharmaceutical industry, food production, forensic analysis, among others.

4. Final Reflection (1-2 minutes): Finally, the teacher should propose that the students reflect for a minute on the following questions:

   4.1. "What was the most important concept you learned today?"

   4.2. "What questions have not been answered yet?"

   After the minute of reflection, the students can be invited to share their answers, if they feel comfortable. The teacher should use these answers to evaluate the effectiveness of the class and to identify possible points of improvement for future classes. Furthermore, the students' answers can help them strengthen what they have learned and to identify any areas of doubt that need to be addressed in future classes.

Conclusion (5-7 minutes)

1. Content Summary (2-3 minutes): The teacher should start the Conclusion by summarizing the main contents covered in the class. He should recall the nomenclature of aliphatic hydrocarbons (alkanes, alkenes and alkynes), the identification and naming of isomers, and the rules for naming hydrocarbons with branched groups. The teacher should emphasize that the correct identification and naming of these compounds is essential for understanding their properties and for the safety and effectiveness of different products.

2. Theory-Practice Connection (1-2 minutes): Next, the teacher should explain how the class connected theory with practice. He should highlight that the theory was presented in a clear and didactic way, and that the practical exercises helped the students to apply the acquired knowledge and to develop their skills of identification and naming hydrocarbons. Furthermore, the teacher can mention that the classroom discussion allowed the students to share their ideas and solutions, which enriched everybody's learning.

3. Complementary Materials (1-2 minutes): The teacher should then suggest some complementary materials for the students who want to deepen their knowledge of the topic. These materials can include chemistry books, educational websites, explanatory videos, among others. The teacher should make sure that the students know where to find these materials and encourage them to explore them at their own pace.

4. Importance of the Topic (1 minute): Finally, the teacher should highlight the importance of the topic discussed in the students' everyday lives. He can mention that the correct identification and naming of chemical compounds is essential in different areas, such as medicine, pharmacy, the food industry, among others. Furthermore, the teacher can explain that the ability to think in a logical and systematic way, which was developed during the class, is a valuable skill that the students can apply in any area of study or work.