Topic: Alkanes – physical properties

Target group

Elementary school student (grades 7. and 8.)

Core curriculum

VIII. Compounds of carbon with hydrogen - hydrocarbons. Pupil:

3) observes and describes the physical properties of alkanes; indicates the relationship between the length of the carbon chain and the physical properties in a series of alkanes (density, melting point and boiling point).

General aim of education

The student discusses the physical properties of alkanes

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• how to explain the effect of carbon chain length on the physical properties of alkanes, e.g. on the physical state;

• to plan experiments to study the properties of alkanes on the example of methane and ethane;

• how to observe and describe physical and chemical properties (combustion reactions) of alkanes on the example of methane and ethane.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• exposing

  • film.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

3. Health and safety – before starting the experiments, students familiarise themselves with the safety data sheets of the substances that will be used during the lesson. The teacher points out the need to be careful when working with them.

Realization

1. The teacher remind students of the properties of saturated hydrocarbons - they are a group of chemical compounds of similar composition, all have carbon and hydrogen - are their properties similar? This question encourages students to analyze the data during the lesson.

2. The teacher performs an experiment with the abstract „Obtaining methane and testing its physical properties”. Students formulate a research question and hypotheses, write them in the observation diary in abstract. They observe changes during the experiment, draw conclusions about the physical properties of methane and write them down.

3. The teacher asks students to perform a task using data from the table in the abstract, describing the properties of alkanes, taking into account the dependence of the number of carbon atoms on the boiling point and melting in the form of a bar chart. He also asks to read in the chemical tables the density of the first five hydrocarbons from a series of homologous alkanes. Discussion ensues.

4. The teacher asks students (individual work) to perform tasks and interactive exercises in an abstract.

Summary

1. The teacher asks the students to finish the following sentences:

   • Today I learned ...

   • I understood that …

   • It surprised me …

   • I found out ...

   The teacher can use the interactive whiteboard in the abstract or instruct students to work with it

2. The student indicated by the teacher sums up the lesson, telling what he has learned and what skills he/she has been practicing.

Homework

1. Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

2. Make at home a note from the lesson using the sketchnoting method.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Alkanes – physical properties

The physical properties of alkanes change as the number of carbon atoms in their molecules increases – they move from the gaseous state through the liquid state to the solid state. Look at the dropdown table and memorize what the physical properties of alkanes are.

• Physical properties of alkanes change as the length of carbon chain is increasing.

• Alkanes are colorless substances of low density, they are not soluble in water.