Lesson plan of Properties of Organic Compounds: Boiling and Melting Points

Objectives (5 - 10 minutes)

1. Organic Compounds Properties Introduction: The teacher should begin the class by revisiting the basic concepts of organic compounds and their molecular structure. This includes reviewing covalent bonds and the importance of carbon in organic chemistry.

2. Boiling and Melting Points: Next, the teacher should introduce the concepts of boiling and melting points. Students should understand that the boiling point is the temperature at which a liquid turns into a gas, while the melting point is the temperature at which a solid turns into a liquid.

3. Molecular Structure and Properties Relationship: The teacher should then explain how the molecular structure of an organic compound determines its physical properties, including its boiling and melting points. This involves discussing how the strength and nature of the chemical bonds influence these properties.

4. Specific Goals: Based on these concepts, students should be able to understand the relationship between molecular structure and the boiling and melting points of organic compounds. Furthermore, they should be able to predict the behavior of organic compounds based on their molecular structure.

   • Identify the relationship between molecular structure and the boiling and melting points of organic compounds.
   • Predict the behavior of organic compounds based on their molecular structure.

Introduction (10 - 15 minutes)

1. Previous Content Review: The teacher should begin the class by reviewing the basic concepts of covalent bonds and the importance of carbon in organic chemistry. This can be done through a brief interactive review, where students are asked to share what they remember from these concepts. The teacher can then supplement the students' answers with additional information, if necessary. (3 - 5 minutes)

2. Problem Situations: The teacher should then present two problem situations to arouse the students' interest in the topic of the class:

   • "Why does gasoline, which is an organic compound, evaporate faster than water, which is an inorganic compound?"
   • "Why does sugar, which is an organic compound, melt when heated, while salt, which is an inorganic compound, needs to reach a much higher temperature to melt?"

   These questions should be left open-ended and returned to at the end of the class, after the boiling and melting points have been explained. (3 - 5 minutes)

3. Contextualization: The teacher should then contextualize the importance of the topic, explaining that knowledge of the physical properties of organic compounds is essential in several areas, such as the pharmaceutical, chemical, food, and fuel industries. In addition, the teacher may mention that understanding how molecular structure affects the physical properties of compounds is fundamental to the development of new materials and technologies. (2 - 3 minutes)

4. Topic Introduction: Finally, the teacher should introduce the topic of the class - "Properties of Organic Compounds: Boiling and Melting Points" - explaining that boiling and melting points are important physical properties of compounds, which can be used to identify and characterize different substances. The teacher can then share the objective of the class and what the students are expected to learn. (2 - 3 minutes)

Development (20 - 25 minutes)

1. Theory - Boiling and Melting Points (8 - 10 minutes):

   • The teacher should begin by explaining the concept of boiling point, which is the temperature at which a liquid turns into a gas. They should emphasize that the boiling point depends on the pressure of the environment, and that, under normal pressure conditions, the boiling temperature is a chemical characteristic that helps identify a compound.
   • Next, the teacher should explain the concept of melting point, which is the temperature at which a solid turns into a liquid. As with the boiling point, the melting point is also a characteristic property of a compound.
   • The teacher should then present the difference between pure substances and mixtures, explaining that pure substances have well-defined boiling and melting points, while mixtures have boiling and melting point ranges.
   • Finally, the teacher should explain that the change in physical state of a substance (from solid to liquid or from liquid to gas) occurs when the kinetic energy of the substance's particles overcomes the force of attraction between them.

2. Theory - Chemical Bonding and Properties (8 - 10 minutes):

   • The teacher should then explain how the molecular structure of an organic compound determines its physical properties. They should recall that organic compounds are characterized by covalent bonds, which are strong bonds that share electrons between atoms.
   • The teacher should emphasize that the strength and nature of the chemical bonds influence the physical properties of the compounds, including the boiling and melting points. For example, the stronger the chemical bond, the more energy is required to break it and, therefore, the higher the boiling and melting point of the compound.
   • The teacher should also discuss the importance of intermolecular interactions, such as Van der Waals forces and hydrogen bonds, which also influence the physical properties of the compounds. For example, compounds that form hydrogen bonds tend to have higher boiling and melting points due to the strength of these interactions.

3. Practical Application - Examples and Exercises (4 - 5 minutes):

   • The teacher should then present some examples of organic compounds with different molecular structures and discuss how these structures affect their boiling and melting points. For example, they could compare the boiling point of gasoline (composed mainly of hydrocarbons) to that of water (an inorganic compound), explaining that gasoline, due to its molecular structure, has a lower boiling point than water.
   • The teacher should then propose some exercises for the students to practice applying the concepts they have learned. For example, they could ask the students to predict which compound from a given list will have the highest boiling point, based on their molecular structures.
   • While the students are solving the exercises, the teacher should circulate around the room, monitoring the students' work and clarifying any doubts, if necessary.

Summing-up (10 - 15 minutes)

1. Concept Review (5 - 7 minutes): The teacher should begin the Summing-up stage by reviewing the main concepts covered in the class. They should reinforce the definition of boiling and melting points, and the relationship between molecular structure and these properties of organic compounds. The teacher should ask direct questions to the students to check if they are understanding the concepts, giving them the opportunity to express their doubts.

2. Connecting to Practice (3 - 4 minutes): The teacher should then connect the theory to the problem situations presented at the beginning of the class. They should explain how the knowledge acquired about the boiling and melting points of organic compounds can be applied to understand why gasoline evaporates faster than water, and why sugar melts at a lower temperature than salt. The teacher should emphasize that these phenomena are explained by the differences in the molecular structures of the compounds.

3. Individual Reflection (2 - 3 minutes): The teacher should then propose a moment for individual reflection, where the students will have one minute to think silently about the answers to the following questions:

   1. "What was the most important concept learned today?"
   2. "What questions have not yet been answered?"

   After this minute, the teacher should ask some students to share their answers with the class. The aim of this activity is to encourage the students to reflect on what they have learned and to identify possible gaps in their understanding.

4. Students' Feedback (1 - 2 minutes): Finally, the teacher should ask the students to give feedback on the class, based on the questions:

   1. "What did you like the most about today's class?"
   2. "What could be improved in the class?"

   This activity is important for the teacher to assess the effectiveness of their teaching approach and to make necessary adjustments for future classes.

Conclusion (5 - 10 minutes)

1. Class Summary (2 - 3 minutes): The teacher should begin the Conclusion by recapping the main points covered in the class. They should recall the concepts of boiling and melting points, and how the molecular structure of organic compounds influences these properties. The teacher can use a visual summary, such as a concept map or a diagram, to facilitate the students' understanding and memorization of the concepts.

2. Connecting Theory to Practice (1 - 2 minutes): The teacher should then reinforce how the theory presented in the class connects to practice. They should again mention the problem situations presented at the beginning of the class and explain how the concepts of boiling and melting points of organic compounds allow us to understand these phenomena. The teacher can also cite examples of practical applications of these concepts, such as in the pharmaceutical, chemical, and fuel industries.

3. Extra Materials (1 - 2 minutes): The teacher should then suggest extra materials for students who wish to deepen their understanding of the topic. These materials could include books, articles, videos, and websites related to organic chemistry and the properties of compounds. For example, the teacher could indicate an explanatory video on boiling and melting points, a website with a list of boiling and melting points of different compounds, and an organic chemistry textbook for further reading.

4. Importance of the Topic (1 - 2 minutes): Finally, the teacher should highlight the importance of the topic presented for the students' daily lives and careers. They should explain that knowledge of the physical properties of organic compounds is fundamental in several areas, such as the pharmaceutical, chemical, food, and fuel industries. In addition, the teacher can mention that understanding how molecular structure affects the physical properties of compounds is essential for the development of new materials and technologies.