Topic 4: MATTER – Chemistry Form One Notes
Definition: Matter is anything that has mass (weight) and occupies space.
Example: stones, vegetation, air, food, water and animal bodies
Mass is a measure of quantity of matter in an object. It is measured in kilogram (kg) or grams (gm).
Matter is everything that is found within our environment such as stones, , vegetation, air, food, water and our bodies
STATES OF MATTER
There are four fundamental states of matter which are;
(i) Solid
(ii) Liquid
(iii) Gas
(iv) Plasma
The solid, liquid and gas states are composed of particles called atoms while plasma state is composed of charged particles.
The liquid, gases and plasma are classified as fluids because their particles have ability to flow due to their constant random motion.
SOLID
Solid is a substance that has definite shape and size. Solid also has definite volume.
It is usually hard and not easily deformed. Eg stone, wood, sugar, sand, paper, iron, table, charcoal, cooking pot, pencil, etc
LIQUID
Liquid is a substance which flows easily and has definite volume. A liquid takes the shape of the container holding it. Examples of liquids are water, kerosene, petrol, diesel, spirit (alcohol), milk, blood, juice, paints, oil, etc.
GASES
Gases have no fixed shape or size. They flow easily and expand indefinitely to occupy the space in which they are held.
Examples of gases are oxygen gas, hydrogen gas, carbon dioxide, water vapour, nitrogen gas, chlorine gas, ammonia etc.
PLASMA
Plasma is a state of matter which occurs when a gas is extremely heated to form a mixture of positively charged ions and free electrons.
Plasma is a charged gas that is less dense than solids or liquids and lacks the fixed shape and volume.
Plasma occurs naturally in a
(i) Stars and lighting
(ii) Industrial processes
(iii) Manufactured products like plasm televisions (TV’s)
EXERCISE
1. What are the conditions for a substance to be called matter?
2. Why are liquids and gases categorized as fluids?
3. Describe solids, liquids and gases in terms of shape and volume.
4. Why do gases expand more than solids for the same increase in temperature?
CHANGE OF STATE IN MATTER
Matter may change its state from one form to another. This can be caused by change in temperature and pressure of matter. For example, when heated some solids melts to liquids, while liquids changes to gas (vapour) and vapour changes to plasma under high temperature. An example of a substance which exists all four states of matter is water.
PROCESSES INVOLVED IN CHANGES OF STATES OF MATTER
(i) Melting and freezing
Melting
Melting is a process in which a substance changes from a solid to liquid.
When a solid is heated, the particles gain energy and vibrate fast and finally they break free from their fixed position and begin to move in clusters.
MELTING POINT is the temperature at which the solid changes to liquid at standard temperature and pressure.
For example, melting point of ice (water) is 0oC. Substances with strong force of attraction between their particles have high melting points and the ones with weak force of attraction between particles have low melting point.
Freezing
Freezing is the process in which a substance changes from a liquid to a solid on cooling.
FREEZING POINT is the temperature at which a liquid change to a solid.
For example, the freezing point of water is 0oC.
(ii) Evaporation (Vapourization)/ boiling and condensation
Evaporation
Evaporation (vapourization) is a process of changing liquid to gas (vapour) on heating at any given
Temperature
When a liquid is heated, the particles move faster as their average kinetic energy increases. Some of the
particles at the surface of the liquid gain enough kinetic energy and escape into the air.
Boiling
Boiling is a change of state of matter from liquid to (gas) vapour state at a particular temperature.
The temperature at which the liquid starts to boil is called boiling point.
Definition: Boiling point is the temperature at which the vapour pressure of the liquid is equal to the
atmospheric pressure.
NB: Boiling point of a liquid is affected by atmospheric pressure. Liquids have low boiling points at low pressure and high boiling points at high pressure.
DIFFERENCES BETWEEN EVAPORATION AND BOILING
| Evaporation | Boiling |
| 1.Occurs at all temperatures | Occurs at one particular temperature (boiling point) |
| 2.Occurs on the surface of the liquid | Occurs both inside and on the surface of the liquid |
| 3.Takes place slowly | Takes place (rapidly) faster |
| 4.Bubbles are not necessarily formed | Bubbles are formed |
NB: The boiling point of a liquid is affected by the atmospheric pressure. For example at low temperature water may vapourize even at room temperature, ie it boils at very low temperature.
Condensation-
Condensation is the process of changing gas to liquid on cooling.
(iii) Sublimation and deposition.
Sublimation
Sublimation is a process of changing solid directly to gas without passing through liquid on heating.
Deposition
Deposition is the process of changing gases directly to solid without passing into liquid state on
cooling.
(iv) Ionization and deionization
Ionization
Ionization is a process which occurs when neutral atoms lose electrons forming ions (charged particles).
Ionization occurs when a gaseous state of matter is subjected to a very high temperature.
Deionization
Deionization is the recombination of free ions and electrons of the plasma to form atoms that finally combine to form gas molecules.
OR
Deionization is a process which occurs when the ions and free electrons in the plasma recombine to form neutral atoms or molecules.
Deionization occurs when temperature is decreased.
SUMMARY ON THE CHANGES OF STATE OF MATTER FOR FOUR STATES
SUMMARY ON THE CHANGES OF STATE OF MATTER FOR ONLY SOLID, LIQUID AND GAS
EXERCISE
1. Describe melting and freezing according to the states of matter
2. What do you understand by the following terms
(i) Melting
(ii) Freezing
(iii) Boiling
(iv) Evaporation
(v) Sublimation
(vi) Deposition
3. Explain the differences between evaporation and boiling.
4. Why do cold foods not smell from a distance?
5. Differentiate between sublimation an deposition
MPORTANCE (SIGINIFICANCE) OF CHANGE IN STATE
The following are the importance of change in state of matter in our daily lives:
1. WATER CYCLE (FORMATION OF RAIN)
Water cycle is the movement of water on, above and below the earth’s surface.
In water cycle water changes from liquid to vapour by evaporation, from vapour to clouds by condensation and finally clouds to rain.
Therefore, rain is formed mainly through evaporation and condensation
2. DRYING OF MATERIAL)
Drying of materials occurs through evaporation whereby the liquid contained in the material changes to vapour.
For example, drying of clothes and food stuffs such as vegetables, cassava and maize. Farmers in the village often spread crops on the ground to dry.
Evaporation is also used to dry wet clothes suspended on a cloth line as a result of the heat produced by the sun.
3. REFRIGERATION / AIR CONDITIONS
Refrigerators use refrigerants which are chemicals whose change in state involves the change in energy.
The change of state of refrigerants from liquid to vapour absorbs heat from the surroundings and thus causing the cooling. Air conditions work in the same way
4. STEAM ENGINES
Steam engines use steam as working fluid to perform work. The change of state from liquid water to steam makes steam engines to operate. Steam engines were used in early trains and ships.
5. METALLURGY (PURIFICATION OF METALS)
Metallurgy involves the extraction and purification of metals from their ores and the manufacture of alloys.
The change of state from solid to liquid and from liquid to solid make metallurgy possible.
6. SEPARATION OF MIXTURES
Different mixtures can be separated by processes such as distillation, sublimation, evaporation and condensation eg A mixture of two or more substances with different boiling points e.g. water and alcohol can be separated by fractional distillation which involves evaporation and condensation.
7. REFINERY
Petroleum refinery and distillery work under the principle that the liquids can change to vapour and then vapour can be cooled to liquids.
While simple distillation is used in distilleries, fractional distillation is applied in petroleum refineries.
8. PRODUCTION OF ELECTRICITY.
Coal is used to heat water in closed system of pipes into vapour. The produced vapour is led by pipes to drive the turbines that in turn produce electricity
9. COOLING OF OUR BODIES IN HOT WEATHER
During hot weather, our bodies perspire a lot (undergo sweating). When water evaporates from the body, it takes up heat. This brings about the cooling effect, as heat is lost from the body surface.
EXERCISE
1. Explain the roles of temperature in the changes of states of matter
2. Why do cold foods not smell from distance?
3. Provide real world examples of how the knowledge of changes in states of matter is applied in industries.
PARTICULATE NATURE OF MATTER
Matter is made up of particles. This was proved by the phenomenon known as Brownian motion.
Brownian motion.
In 1827, a botanist called Robert Brown observed through a microscope that pollen grains suspended in water moved short distances in an irregular zigzag manner.
This is because they are constantly bombarded by particles of water which cannot be seen even through a laboratory microscope. This shows that matter is particulate in nature.
Brownian motion state that “Matter is made up of tiny particle that are in a state of continuous random motion”
Other examples which show that matter is made up of particles that are in constant motion include (i) The spread of the smell of the food being cooked from the kitchen to considerable distance,
(ii) Diffusion of potassium permanganate particles in water
(iii) The spread of perfume due to diffusion of perfume vapour into the air.
Diffusion is the movement of particles from an area of high concentration to the area of low concentration.
BEHAVIOUR OF PARTICLES IN MATTER
All matters are made up of small particles. The behaviour of these particles differs in the three states of matter.
In solids particles are firmly packed, in liquid particles are close together while in gas particles are far apart as can be seen in the diagram below.
Properties of Solid state
(i) Particles very closely (firmly) packed together
(ii) Has definite shape and volume
(iii) Has strongest inter-particle force
(iv) Particles are not free to move
(v) Particles cannot be compressed.
(vi) Particles vibrate in fixed position.
(vii) Has high forces of attraction between the particles
(viii) It does not flow
Properties of Liquid state
(i) Particles are close together
(ii) Have definite volume
(iii) Does not have definite shape, it takes the shape of the container
(iv) Has medium density due to medium volume
(v) Molecules in a liquid can move in all direction with medium motion
(vi) Inter-particle force is weak
(vii) It can flow easily.
(viii) Particles in liquids cannot be compressed because are close together
Properties of Gas state
(i) Particles are far apart from each other
(ii) Has no definite shape
(iii) Has no definite volume
(iv) Particles have largest distance from each other
(v) Has low density due to largest volume
(vi) Has weakest inter particle force
(vii) Particle moves in all directions with high speed
(viii) The particles are randomly arranged.
(ix) It can flow easily.
(x) Particles in gases can be compressed because are far apart.
Properties of plasma state
(i) Has no definite shape
(ii) Has no definite volume, takes volume its container
(iii) Particles move freely like in gas and are highly energetic
(iv) Particles can flow easily
THE TABLE BELOW IS NOT COMPLETE
SUMMARY OF THE PROPERTIES OF MATTER
| PROPERTIES | SOLID | LIQUID | GAS | PLASMA |
| Shape | Has fixed shape | Takes shape of its container | Has no definite shape, fills the shape of the container | Has no definite shape, fills the shape of the container |
| Volume | Has a fixed volume | Has a Fixed volume | Takes volume of its container | Takes volume of its container |
| Movement of particles | Particles do not move except vibrations | Particles move or slide past one another | Particles move randomly in all directions | Highly energetic freely moving and regularly colliding particles |
| Compressibility | Generally incompressible | Relatively incompressible | Highly compressible | Highly compressible |
| Space between particles | No free space between particles | Little free space between particles | A lot of free space between particles | Highly variable depending on the type of plasma |
| Electrical conductivity | Poor electrical conductivity, except for conductive solids like metals | Some liquids can conduct electricity, but generally lower than metals | Poor electrical conductivity due to lack of free electrons | High electrical conductivity because there are free electrons present |
| Flow | Does not flow easily | Flow easily | Flow easily | Flows easily |
KINETIC THEORY OF MATTER
The kinetic nature of matter refers to the idea that “All matter is made up of tiny particles called atoms and molecules that are in constant motion”.
It explains the behaviour and properties of matter in terms of the motion of its particles which determines the properties of solids, liquids and gases.
Key points of the kinetic nature of matter are:-
(i) All matter is made up of tiny invisible particles (atoms and molecules)
(ii) The particles in matter are always in constant motion, i.e moving all the time.
(iii) The particles of matter are held together by force of attraction in which solids have strong
electrostatic forces.
(iv) The movement of particles is due to kinetic energy which depends on temperature
(v) Heavier particles move more slowly than lighter particles at the same temperature.
(vi) There are empty spaces between the particles of matter
NB: The idea about the way particles behave in solids, liquid and gases is called kinetic molecular theory.
PHYSICAL AND CHEMICAL CHANGES
There are two major changes which are Physical change and Chemical changes;
Physical change affects the physical properties of matter while chemical change affects both physical and chemical properties of matter
(a) PHYSICAL CHANGE
DEFINITION: Physical change is a change in which no new substance is formed.
This is a temporary change which involves change in physical properties of matter such as colour, shape,
Examples of physical changes include: melting of ice, freezing of water, evaporation of water, dissolving salts in water, melting of candle wax, magnetization of iron, heating a metal (iron or wire) to red hot, crushing, tearing, condensation, sublimation, etc
(b) CHEMICAL CHANGE
DEFINITION: Chemical change is a change in which a new substance is formed
This is a permanent change which involves changes in chemical properties of a matter
Examples of chemical changes include rusting of iron, burning of piece of paper, souring of milk, cooking of food, decaying of meat, rotting of egg, fermentation of fruits, burning of candle etc .
DIFFERENCES BETWEEN PHYSICAL CHANGES AND CHEMICAL CHANGES
| PHYSICAL CHANGE | CHEMICAL CHANGE |
| 1. No new substance is formed | A new substance is formed |
| 2. Are temporary changes | Are permanent changes |
| 3. The change is easily reversible | The change is irreversible (cannot be reversed) |
| 4. No energy is given out or absorbed | Energy is given out or absorbed |
| 5. Affects only physical properties of matter | Affect both physical and chemical properties of matter |
| 6. There is no change in mass or weight of the substance | There is a change in the mass or weight of the Substance |
| 7. Molecules are rearranged while their actual compositions remain same | The molecular composition of a substance are completely changed |
RUSTING
Rusting is a chemical change that occurs on the surface of iron materials and forms reddish – brown coating.
The reddish – brown coating is called RUST.
CONDITIONS FOR RUSTING
There are three conditions necessary for rusting of iron to occur which are
(i) Iron
(ii) Oxygen
(iii) Water
Therefore, Iron will not rust on exposure to dry air or air-free water (water that has been boiled to expel all dissolved air). However, iron will easily and readily rust in water that has dissolved air in it.
Diagram below shows that only the iron nail that is in contact with both water and air rusts.
Diagram to show Testing for conditions necessary for iron rusting
OBSERVATION
Nails in test tube A and D will rust. Nails in tubes B and C will not rust.
Reasons
In test tube A nails are in contact with both water and air (oxygen), hence rusting will occur.
In test tube B, iron nails will not rust because water has been boiled to remove oxygen and oil prevent oxygen from dissolving in it
In test tube C, iron nails will not rust because they are in contact with air only. Anhydrous calcium chloride absorbs any water in the test tube.
In test tube D, iron nails will rust but the process will take long time to occur because they are in contact with air but the amount of water in air is less.
METHODS USED TO PREVENT RUSTING
In order to stop rusting iron should be protected from coming in contact with either water (moisture) or oxygen (air) or both.
The following are some of the methods used to prevent iron from rusting:
(i) Painting
(ii) Oiling and greasing
(iii) Galvanization
(iv) Tin plating
(v) Use of silica gel
(vi) Sacrificial protection
(vii) Alloying
1. Painting– This is a process of coating iron items with a special pigment or paint. The paint coating
prevent oxygen and water from coming into contact with the iron material.
2. Oiling and greasing –This is the coating of iron with oil or grease, some machine parts cannot be
protected by painting so they use oil.
3. Galvanization: This is the process of coating iron or steel with zinc.
This is possible because zinc is more reactive than iron.
4. Tin plating: This is a process of coating iron/steel with tin.
5. Use of silica gel: Silica gel is a substance in the form of grains which absorbs moisture.
Silica gel prevent water from reaching iron/steel.
A small bag of silica gel is put inside bags or boxes used for storing or
carrying iron items to absorb any moisture that may cause rusting.
6. Sacrificial protection (anodizing)
In this technique the corrosion of a metal surface is controlled by making it the cathode of an electrochemical cell.
The sacrificial metal then corrodes instead of the protected iron
7. ALLOYING
Alloys are mixtures of metals. For example, iron can be mixed with small quantities of much less reactive metals to form an alloy called stainless steel.
Stainless steel contains iron mixed with chromium, nickel and manganese. Stainless steel does not rust. It is used to make cutlery and kitchen equipment.
NB: An alloy is a mixture of one metal with another metal or non-metal
EXERCISE
1. Classify the following as either physical or chemical changes
(a) Aluminium foil is cut into half
(b) Evaporation of water from the ocean
(c) Milk turns sour
(d) Wood is burnt
(e) Nail or iron sheets rust
(f) Freezing of juice
(g) Drying of clothes
(h) Food is cooked
(i) Amatch is lit
(j) Melting of ice
(j) Dissolving sugar in water
(k) Grinding a piece of paper
2. Explain the importance of change in state of matter (use any five (05) points)