Title: Gases, liquids and solids

Supplementary material for use in lessons in the group of natural sciences (nature, biology, chemistry, geography, physics), additional classes, science clubs. It can serve as a resource for expanding knowledge, preparing students for science competitions.

Lesson plan elaborated by Zyta Sendecka

Target Group

Pupils of the seventh grade of primary school (Chemistry)

Core Curriculum

Grade VII, Chemistry

I. Substances and their properties. Pupil:

3) describes the states of matter.

The general aim of education

Students learn about the states of substances and explain them using a particle model.

Criteria for success

• discuss types of physical states;

• you describe how the particles are arranged in each of the states of matter;

• you will name and explain the processes of changing the states of substances;

• you will explain how a change in temperature affects the state of the substances.

Key Competences

• Communication in the mother tongue;

• Communication in foreign languages;

• Mathematical competence and basic competences in science and technology;

• Digital competence;

• Learning to learn;

• Social and civic competences.

Methods/techniques

Talking, working with text, indirect observation, modeling.

Individual work and frontal work.

Teaching aids

• abstract;

• interactive or traditional board;

• tablets/computers;

• cards with drawn outlines of a cube, jug and balloon;

• round cereals

• glue.

Lesson phases

Introduction

1. The teacher gives the subject and the purpose of the lesson in a language that the student understands as well as the criteria for success.

Realization

1. The teacher asks students to draw up a table that includes the three states of matter (solid, liquid, gas) and write examples of each under the appropriate headings. The students present their suggestions, the teacher checks their accuracy.

2. Students read the section „What are the known states of matter?”. Then complete the table by writing the features of individual states of matter.

3. The teacher distributes the round breakfast cereals, glue and cards with the cube outline, jug and balloon. Next, the teacher presents an animation showing the arrangement of particles in each of the three states of water. The students' task is to imitate the arrangement of particles with the help of the breakfast cereals glued onto the pages, inside the outline of the cube.

4. Students read the section „Changes in physical states” and analyze an interactive illustration showing the effect of temperature change on the state of matter. They write in their notebooks definitions for each of changes of physical states (melting, solidification, evaporation, condensation) as well as boiling point and melting point.

Summary

1. Students independently perform interactive exercises. Volunteers discuss their answers. The teacher complements students' statements and corrects possible mistakes.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Gases, liquids and solids

Scientists know that ice, water and steam are the same substance, but in different forms referred to as states of matter. Oxygen and nitrogen in the air are gases, while oil, water and gasoline are liquids, and salt, sugar and coal are solids. When describing the properties of substances, we always pay attention to the form in which it occurs; solid, liquid or gas. In this way we define the physical state of the substance.

Each state of matter has its own characteristic features. In solid state, the substance retains its own shape. It is difficult to change its volume, which is why we say it is not very compressible. In liquid state the substance takes on the shape of the container in which it is located, but it is still difficult to change its volume. In gaseous state the substance always fills the entire container in which it is located and is compressible. This means that there is no specific shape or volume.

We already know that each substance is made of particles. They are in constant motion. Even in solid materials, the particles vibrate slightly. The physical state of the substance is related to the motion of it’s particles. The fastest particles are in gases, while in solids they almost never move.

The speed of particles moving is determined by temperature, the higher the temperature, the faster the motion of particles and the easier they can detach from others. This means that a change in temperature affects the state of a substance. The process of changing a solid into a liquid is melting, a liquid to gas is called evaporation and boiling. The process of converting gas into liquid is called condensation, a liquid into a solid is called solidification.

Changes in the state of matter do not occur at anytime, but at a certain temperatures. Boiling point is the temperature at which a liquid transforms into a gaseous state rapidly and in its entire volume. Melting point is the temperature at which a solid becomes a liquid (it melts).

• The substances that surround us can exist in three states – as solids, liquids and gases.

• A solid has an unchanging shape and volume.

• The liquid has a constant volume, but it has a variable shape.

• The gas has no specific shape and easily changes in volume.

• The physical state of the substance depends on the temperature. Changes in the physical state of a particular substance take place at strictly defined temperatures.