KINETIC THEORY
Subject :
Basic Science
TERM
SECOND TERM
Week
Week 6
CLASS
JSS 2 / Basic 8
Topic :
KINETIC THEORY
Instructional Materials :
- Mango tree
- Mango fruits falling off mango tree
- Pictures of solid, liquid and gaseous state of matter
Reference Materials
- Scheme of Work
- Online Information
- Textbooks
- Workbooks
- 9 Year Basic Education Curriculum
Previous Knowledge :
The pupils have been taught
in their previous lesson
Behavioural Objectives : At the end of the lesson, the learners will be able to
- Define kinetic energy
- State the properties of solid, liquid and gas
- Explain what change of state means
- Explain sublimation
Entry Behaviour
Learners are familiar with Matter
Content :
KINETIC ENERGY
WEEK SIX
DATE: ………………..
TOPIC: KINETIC THEORY
Greek philosophers Democritus and Leucippus proposed that matter was made up of particles which he called ATOMS. They made various statements about the nature of atoms. These ideas about atoms are stated below.
1. Matter is made up of minute indivisible particles called atoms.
2. Atom cannot be created or destroyed.
3. All the atoms of an element are alike and different from the atoms of all other elements.
4. Atoms combine in small whole numbers to form new substances.
All these ideas collectively form Dalton’s atomic theory. Since Dalton’s atomic theory was proposed, scientist have accepted the idea that matter is made up of small particles called protons, neutrons and electrons.
The Kinetic Theory of Matter states that matter is composed of a large number of small particles that are in constant motion. The law states that the tiny particles of matter are continually moving and so possess kinetic energy. In other words, kinetic theory of matter recognizes that matter is composed of very small particles (ions, atoms and molecules) whose different pattern of arrangements and motions result in the different possible.
Kinetic theory of gases – states that gases consist of small particles in random motion. The kinetic particle THEORY explains the properties of the different states of matter. The particles in solids, liquids and gases have different amounts of energy. They are arranged differently and move in different ways.
Solids
Property of solids
• They have a fixed shape and cannot flow
• The particles cannot move from place to place
• They cannot be compressed or squashed
• The particles are close together and have no space to move into
Liquids
Property of liquids
• They flow and take the shape of their container
• The particles can move around each other
• They cannot be compressed or squashed
• The particles are close together and have no space to move into
Gases
Gases are made up of molecules. What are molecules? Molecules are the smallest unit which behaves same as the sample, i.e. they have the same chemical properties as of the sample.
Property of gases
• They flow and completely fill their container
• The particles can move quickly in all directions
• They can be compressed or squashed
• The particles are far apart and have space to move into
Changes of state : This is the transformation of matter from one form, state or shape to another. There are three states of matter which are solid, liquid and gas. Water is the only matter that can exist in all the three states of matter.
Water can be in solid as ice block.
Water can be in liquid as chilled refreshing cold water.
When water is exposed to high temperature by boiling, water will turn to water vapour in gaseous form.
Melting and freezing
If energy is supplied by heating a solid, the heat energy causes stronger vibrations until the particles eventually have enough energy to break away from the solid arrangement to form a liquid.
When a liquid freezes, the reverse happens. At some temperature, the motion of the particles is slow enough for the forces of attraction to be able to hold the particles as a solid. As the new bonds are formed, heat energy is evolved.
Boiling and condensing
If more heat energy is supplied, the particles eventually move fast enough to break all the attractions between them, and the liquid boils. The heat energy required to convert one mole of liquid into a gas at its boiling point is called the enthalpy of vaporisation.
If the gas is cooled, at some temperature the gas particles will slow down enough for the attractions to become effective enough to condense it back into a liquid. Again, as those forces are re-established, heat energy is released.
The evaporation of a liquid
The average energy of the particles in a liquid is governed by the temperature. The higher the temperature, the higher the average energy. But within that average, some particles have energies higher than the average, and others have energies lower than the average. Some of the more energetic particles on the surface of the liquid can be moving fast enough to escape from the attractive forces holding the liquid together. They evaporate.
Sublimation
Solids can also lose particles from their surface to form a vapour. Sublimation is the direct change from solid to vapour (or vice versa) without going through the liquid stage. For example, naphthalene, dry ice of carbon(iv)oxide, Iodine crystals e.t.c
ASSUMPTIONS OF KINETIC THEORY OF GASES
1. All gases are made up of molecules which are constantly and persistently moving in random directions.
2. The separation between the molecules is much greater than the size of molecules.
3. When a gas sample is kept in a container, the molecules of the sample do not exert any force on the walls of the container during collision.
4. The time interval of collision between two molecules, and between a molecule and the wall is considered to be very small.
5. All the collisions between molecules and even between molecules and wall are considered to be elastic.
6. All the molecules in a certain gas sample obey the Newtons laws of motion.
7. If a gas sample is left for a sufficient time, it eventually comes to a steady state. The density of molecules and the distribution of molecules are independent of position, distance and time.
The main aspects of the kinetic theory are:
- Matter is composed of very tiny particles (atoms or molecules), which are separated from each other by inter particle distances.
- Each particle of matter is in constant motion.
- In a gas, the particles can move around freely and independently.
- In a liquid, particle movement is a bit constrained and limited to sliding/flow movement within its volume.
- In a solid, particle movement is fully constrained and restricted to only vibrational motion of particles in their fixed positions within the solid.
- The particles of matter experience forces of attraction amongst themselves. These attractive forces decrease rapidly with increasing distance between the particles.
- Particles in solids are very close to each other, and the attractive forces are large. enough to hold the particles in fixed positions. Thus, a solid has a fixed shape and a fixed size (volume).
- The particles of liquids are a little further apart and are free to slide and flow, taking the shape of the container. Thus, a liquid has no fixed shape.
Presentation
The topic is presented step by step
Step 1:
The class teacher revises the previous topics
Step 2.
He introduces the new topic
Step 3:
The class teacher allows the pupils to give their own examples and he corrects them when the needs arise
Evaluation
Objectives
1. All of the following can be compressed except———– A. oxygen B. hydrogen C. carbon dioxide D. water
2. In which of the following is the kinetic energy of particles of matter is greatest A. gas B. liquid C. solid D. stone
3. The process whereby a substance in solid state changes directly to gaseous state is known as———— A. freezing B. sublimation C. melting D. cooling
4. Which of these is not a state of matter? A. solid B. water C. liquid D. gas
5. When a liquid is frozen, it turns to a substance in the———— form A. gaseous B. solid C. liquid D. water
THEORY
1. State three each of the properties of solid, liquid and gas.
2. What do you understand by enthalpy of vaporization?
3. State four properties of solid, liquid and gas
4. What are the particles of matter?
5. State three assumption of kinetic THEORY of gases.
7. State four properties of solid, liquid and gas
8. What are the particles of matter?
9. State three assumption of kinetic THEORY of gases.
10. Differentiate between solid, liquid and gas by writing out four characteristics of each
Conclusion :
The class teacher wraps up or conclude the lesson by giving out short note to summarize the topic that he or she has just taught.
The class teacher also goes round to make sure that the notes are well copied or well written by the learners.
He or she does the necessary corrections when and where the needs arise.