FORM 1 SCIENCE NOTES

What is Science?

1. Science is a systematic study of nature and how it affects our lives and the environment.2. Natural phenomena are events that happen around us.3. Example of natural phenomena :

- Growth of a baby into an adult- An object falling to the ground- Melting of ice- Volcano eruptions, earthquakes and tsunami- Thunderstorm, snow and lightning

4. Science is important to us because it - Enables us to understand ourselves and our surrounding environment- Solves mysteries of science through the systematic investigation- Contributes to new discoveries inventions and knowledge gained- Improve our standard of living and quality of our environment- Creates science-based job opportunities

Hazard Warning Symbols

1. Flammable substances May become hot and finally ignite in contact with air White phosphorus, yellow phosphorus, petrol, kerosene, ethanol, methylated spirit

2. Explosive substances May explode under the effect of a flame or if subjected to shocks or friction Sodium, potassium, mixture of hydrogen and air, hydrazoic acid, hydrazine, diazo

3. Corrosive substances May destroy or burn living tissues on contact with them Hydrogen peroxide, concentrated hydrochloric acid, concentrated sodium hydroxide

4. Poisonous or toxic substances May cause immediate or long term health risks and even death if inhaled, ingested

or absorbed into the skin Mercury, bromine, lead, sodium cyanide, chlorine, hydrogen sulphide, benzene

5. Irritating or harmful substances May cause discomfort or inflammation to the body Ammonia, chloroform, bromine vapour, chlorine

6. Radioactive substances May cause cell mutation X-ray, uranium, plutonium, thorium, radium

The steps in a scientific investigation

Identifying the problem

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Forming a hypothesis

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Planning the experiment

Identifying variables Determining apparatus and materials Determining the procedure to carry out the experiment Determining method to collect and analyses data

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Controlling the variables

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Collecting data

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Analyzing and interpreting data

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Drawing a conclusion

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Writing a report

Physical quantities and their units

1. Five physical quantities which can be measured- Length- Mass- Time- Temperature- Electric current

2. Physical quantities can be measured in systeme international d’unites (SI) units.

Physical quantity SI Unit SymbolLength Metre mMass Kilogram KgTime Second sTemperature Kelvin KElectric current Ampere A

Prefix Symbol Numerical valueMega M 1000000Kilo K 1000Centi C 0.01Milli M 0.001Micro µ 0.000001

Weight and Mass

Mass

1. Mass is the amount of matter in an object.2. The more the matter in an object, the bigger is its mass.3. SI Unit – kilogram (kg)4. Mass can measured in gram (g) and milligram (mg).5. Mass can be measured by beam balance and lever balance.

I kg = 1000 g1g – 1000 mg

Weight

1. Weight is the gravitational force acting on an object.2. The greater the force pulling the object towards centres of Earth, the heavier the object.3. Weight is measured in Newton (N).4. Compression balance and spring balance is used to measure weight.

Cell as a unit of life

1. A cell is the basic unit of living things which can function on its own.2. Cells are microscopic and cannot be seen with naked eye.

General structures and functions of animal cells and plant cells

Most cells consist of protoplasm which is surrounded by cell membrane.

Structures Characteristics FunctionNucleus - Is dense and spherical

structure.- Is surrounded by a nuclear

membrane.- Contain chromosomes which

carry genetic materials that determine the characteristics of organisms.

It is the control centre of the cell because it controls all chemical reactions in the cell.

Cytoplasm - Is a flexible, colorless, jelly-like substance.

- Is surrounded by a cell membrane.

- Contains water and chemical substances such as proteins, stored food and minerals.

Acts as the medium for chemical reactions of the cell.

Cell membrane - Is a thin, elastic layer on the outer surface or animal cells.

- Contains fats and proteins.- Is partially permeable. This

means that it allows certain substances to pass through.

Controls the movement of substance in and out the cell.

Cell wall - Is a thick and rigid layer on the outer surface of plant cells.

- Is mainly composed of tough substance called cellulose.

It gives the cell a definite shape.

Chloroplasts - Are tiny, oval structures found inside the cytoplasm of most

They enable green plants to manufacture their won food.

1 N = 0.1 kg1 kg = 10 N

plant cells.- Contain a green pigment called

chlorophyll.- Absorbs light energy and uses

it to make food. This process is called photosynthesis.

Vacuoles - Is a fluid-filled sac found in the cytoplasm.

- Is surrounded by a membrane and is filled with cell sap.

- Contains of a solution of sugars, proteins, minerals.

The vacuole acts as a store of various substances such as water, food, pigments, enzymes, and waste products.

Unicellular organisms

- Are simple organisms that are made up of only one cell- In animal kingdom: Amoeba and Paramecium- In plant kingdom: Pleurococcus, Euglena, Chlamydomonas and yeast.

Multicellular organisms

- Are organisms which have more than one cell- In animal kingdom: mammals, amphibians, reptiles, birds, dish, and Hydra- In plant kingdom: mosses, algae (Chondrus, Spirogyra), ferns.

Life processes of unicellular and multicellular organisms

1. Unicellular organism- Can grow- Sensitive to light, chemical substances, and sharp objects- Main food is bacteria- Its excretory organ is the vacuole- Moves by extending pseudopodium- Breathes through cell membrane- Reproduces asexually

2. Multicellular organism- Main food is zooplankton- Excretes through its excretory pores- Moves by means of its tail and fins- Can grow- Sensitive to light and vibrations in water- Reproduces sexually

- Breathes through gills

Cell organization in the human body

1. Types of cells found in human body :a.) Nerve cells – conducts nerve impulsesb.) Red blood cells – transport oxygen from lungs to all cellsc.) White blood cells d.) Skeletal muscle cells – controls movement of bones and organs of bodye.) Reproduction cells f.) Epithelial cells– controls exchange of substancesg.) Bone cells – functions in the support system of the body

2. Types of tissuea.) Epithelial tissue – protects the tissues beneath itb.) Connective tissue – connects one tissue to another tissue , supports organs in the

bodyc.) Muscle tissue – enables the movement of body partsd.) Nerve tissue – enables body to respond to stimulie.) Carries nerve impulses from one part of the body to another

3. Types of systemsa.) Excretory system – discards toxic waste products produced by the body cellsb.) Reproductive system – produces offspringc.) Respiratory system – inhales oxygen and exhales carbon dioxided.) Lymphatic system – defends the body against disease e.) Skeletal system – provides support and protection to soft internal organsf.) Blood circulatory system – transport food substances, oxygen, hormones, and

others to the entire bodyg.) Endocrine system – produces hormones that control the body’s responses toward

stimulih.) Nervous system – coordinates and controls all bodily activities related to impulses

and reactionsi.) Muscular system – helps in movement of the bodyj.) Digestive system – breaks down complex food into simple substances for easy

absorption by body cells

4. Cells, tissues, organs and systems can be interconnected by the following chart :

Cells → Tissue → Organ → System → Organism

5. The importance of organization of cells :

a.) Enables body to perform life processes simultaneouslyb.) Ensure life processes function efficiently and smoothly

What is matter?

Everything that has mass and occupies space is called matter.

The states of matter

1. Matter is made up of tiny particles which are separate.2. These particles can be composed of atoms or molecules3. An atom is the smallest particle of matter and cannot be further divided.4. A molecule is made up of two or more atoms5. Proofs that matter is made up of tiny and discrete particles

- Dissolving copper (II) sulphate crystals in water- Diffusion of gas

Arrangement of particles in matter

Matter exists as solids, liquids and gases.

1. Arrangement of particles in solids : a.) Are arranged close together and in a regular patternb.) Are very small spaces between particles of a solidc.) Cannot be compressedd.) Volume of a solid is definite

2. Arrangement of particles in liquids :a.) Are arranged closer but not in a regular patternb.) Spaces between the particles of a liquid are biggerc.) Cannot be compressedd.) Shape is not definitee.) Known as fluids because of its flowing property

3. Arrangement of particles in a gas : a.) The particles of a gas are far apart and are not arranged in a regular patternb.) Does not have define shape or volumec.) Large spaces d.) Volumes of a gas increases when the particles move aparte.) Can be compressedf.) Known as fluids because of their flowing property

4. Free motion or Brownian motion is the movement of particles in all directions at high speeds.

The concept of density

Density and buoyancy

1. Density of a substance is the mass per unit volume Formula:

density g/cm ³= mass (g)volume(cm3)

2. The SI Unit for density is kg/m³ or kg m-³.3. The density of a substance depends on two factors :

a.) Mass - The bigger its mass, the bigger is its density.b.) Volume- The bigger its volume, the smaller is its density.

4. Buoyancy of a matter refers to whether the matter floats on or sinks in another matter.5. A solid that has a lower density than the density of a liquid will float on the surface of

the liquid6. A solid that has a higher density than the density of a liquid will sink in the liquid

The variety of resources on earth

Water, air, soil, mineral, fossil fuels and living things are the most important things.

Elements, Compounds and Mixtures

Elements

1. An element is the simplest substance.2. All elements made up of only one type of atom.3. Examples of elements :

a.) Goldb.) Zincc.) Irond.) Oxygene.) Carbonf.) Nitrogeng.) Hydrogenh.) Aluminium

4. Elements can be grouped into metals and non-metals.

Metals

1. Examples of metals :a.) Potassium

b.) Calciumc.) Magnesiumd.) Mercurye.) Leadf.) Sodiumg.) Silverh.) Copperi.) Platinumj.) Gold

2. The properties of metals :

Surface appearance – metals have shiny surfaces and can be polished

Heat conductivity – metals are good conductors

Electrical conductivity – metals are good conductors of electricity

Density – metals have high densities

Malleability – metals are elastic

Melting point – metal have high melting points

State of matter – metal is solid at room temperature except mercury

Non-metals

1. Example of non-metals :a.) Hydrogenb.) Fluorinec.) Carbond.) Brominee.) Nitrogenf.) Oxygeng.) Chlorineh.) Phosphorusi.) Iodinej.) Sulphur

Condition at room temperature Examples of non-metalsSolid Carbon, sulphur, iodine, selenium, phosphorus

Liquid Bromine, mercuryGas Hydrogen, helium, oxygen, fluorine, neon, chlorine, argon,

krypton, xenon, radon

2. The properties of non-metals :

Surface appearance – non metals have dull surfacesHeat conductivity – non metals are poor heat conductorsElectrical conductivity – non metals are poor electrical conductorsDensity – non metals have low densitiesMalleability – non metals cannot be beaten into other shapes and are brittleMelting point – non metals have low melting pointsState of matter – non metals can exist as solids, liquids or gases at room temperature

Compounds

1. A compound is formed when two or more types of elements combine chemically.2. The smallest particle in a compound is the molecule.3. Several types of compounds and their components:

a.) Carbon dioxide – one carbon atom, two oxygen atomsb.) Sodium chloride – one sodium atom, one chlorine atomc.) Benzene – six carbon atoms, six hydrogen atomsd.) Methane – one carbon atom, four hydrogen atomse.) Ammonia – one nitrogen atoms, three hydrogen atomsf.) Water – one oxygen atom, two hydrogen atoms

4. The components of a compound cannot be separated physically5. The components of a compound can only be separated chemically.

Example by using high heat or using electrolysis.

Mixture

1. A mixture is made up of two or more substances combined physically for example, by stirring.

2. Mixtures are divided into two types of homogeneous mixture and heterogeneous mixture.

3. A homogeneous mixture is formed when its substances are mixed evenly and the identity of each substance cannot be identified so easily. Example: common salt solution and soft drinks.

4. A heterogeneous mixture is formed when its substances can be identified easily. Example: air.

5. Substances in a mixture can be separated physically as follows:a.) Mixture of sand and water – Filtrationb.) Mixture of flour and sand – Siftingc.) Mixture of common salt and water – Evaporationd.) Mixture of alcohol and water – Distillation

e.) Mixture of chlorophyll pigments – Chromatographyf.) Mixture of water and oil – Extractiong.) Mixture of iron fillings and sulphur – Using a magneth.) Mixture of soil and water – Precipitation

6. A mixture can be converted to a compound by heating.For example, iron filings and sulphur form a compound called iron (II) sulphide or ferrum (II) sulphide when they are heated.

Iron + Sulphur →heat→ Iron (II) sulphide

The composition of air

1. Air is a mixture of various substances that is odourless, colourless, or tasteless.2. Water vapour in the air depends on the humidity in the air. The more humid the air, the

more the water vapour in the air.

3. Examples of inert gases are:a.) Dustb.) Water vapourc.) Microorganisms

Nitrogen 78%

Oxygen 21%

Carbon dioxide 0.03%

Inert gas and others 0.97%

The properties of oxygen and carbon dioxide

1. Air is made up of three main gases: oxygen, carbon dioxide and nitrogen.2. Each gas has its own chemical properties.3. The properties of the gases can be observed by :

a.) Solubility in the waterb.) Reaction with sodium hydroxidec.) Effects on- Glowing wooden splinter- Burning wooden splinter- Litmus paper- Lime water- Hydrogen carbonate indicator

4. Nitrogen is a gas that does not react chemically.

Properties Observation and conclusionOxygen Carbon dioxide

Colour None NoneSmell None NoneSolubility in water

The level of water in the test tube rises slightly. Oxygen is slightly soluble in water.

The level of water in the test tube rise a lot. Carbon dioxide is soluble in water.

Reaction with sodium hydroxide

The level of water does not rise. Oxygen is not soluble in sodium hydroxide.

The level of water in the test tube rises a lot. Carbon dioxide is very soluble sodium hydroxide.

The effect on glowing wooden splinter

The glowing wooden splinter bursts into flame. Oxygen supports combustion.

The glowing wooden splinter extinguishes. Carbon dioxide does not support combustion.

The effect on burning wooden splinter

The burning wooden splinter burns even brighter. The gas is non-flammable. Oxygen supports combustion but is not self-combustible.

The burning wooden splinter extinguishes. The gas is non-flammable. Carbon dioxide does not support combustion and is not self combustible.

The effect on moist litmus paper

The litmus papers do not change colour. Oxygen is neutral.

The blue litmus paper turns red. Carbon dioxide is slightly acidic.

The effect on lime water

The lime water does not change colour.

Carbon dioxide turns the lime water cloudy.

The effect on hydrogen carbonate indicator

The red indicator does not change colour.Oxygen is neutral.

The red indicator turns yellow. Carbon dioxide is slightly acidic.

Oxygen is needed for respiration

1. Air that is breathed into the body is called inhaled air.2. Air that is breathed out of the body is called exhaled air.3. Oxygen is needed for respiration:

- Inhaled oxygen will be dissolved at the surface of the moist alveolus.- Oxygen will be absorbed into the blood capillary through the thin alveolus wall.- Oxygen is then transported by red blood cells to the other blood cells for the

process of respiration.- At the same time, carbon dioxide and water from blood capillaries will be absorbed

alveolus.- Carbon dioxide and water will be expelled body when air is exhaled.

Oxygen is needed for combustion

1. Combustion is a process that takes place when a substance unites with oxygen chemically and this produces energy and light.

2. Without oxygen. Combustion cannot occur because chemical process does not take place.

3. Carbon is a chemical compound that is made up of the carbon element only.4. Combustion of carbon releases carbon dioxide, heat energy and light energy.5. Examples of carbon are wood, cloth, charcoal, and paper.

Carbon + Oxygen → Carbon dioxide + Heat energy + Light energy

6. Hydrocarbon is a chemical compound which is formed from only hydrogen and carbon.7. Combustion of hydrocarbon produces carbon dioxide, water, heat energy and light

energy. 8. Water is formed when hydrogen from hydrocarbon combines with oxygen during

combustion.

Hydrocarbon + Carbon → Carbon Dioxide + Water + Heat energy + Light energy

9. Combustion produces light energy and heat energy.10. Carbon dioxide produced is absorbed by green plants to conduct photosynthesis.

Source of energy

1. Energy is defined as the ability to do work.2. Energy is measured in joules (J).3. Energy can be found in many forms:

a.) Kinetic energy b.) Potential energyc.) Light energyd.) Electrical energye.) Sound energyf.) Nuclear energyg.) Heat energyh.) Chemical energy

4. Kinetic energy - Is the energy possessed by a moving object- Depends on mass and velocity- Will increase if

a.) The mass of the object increasesb.) The velocity of the object increases

5. Potential energy- Is the energy stored in a body due to its position or its physical condition- Depends on

a.) The mass of the objectb.) The distance of the object from the Earth’s surfacec.) The power of the gravitational pull on the object

- Will increasesa.) The mass of the object increasesb.) The higher the object is raised from the groundc.) The gravitational pull on the object increases.

- A falling object can gain kinetic energy but loses potential energy- Elastic potential energy can only elastic substances such as a spring or a rubber.

6. Heat energy- Is the energy that is stored in a hot object- Depends on its temperature and volume- Flows from a hot area to a cold area by conduction, convection and radiation.

7. Light energy - Is the energy produced by an object that emits light- Can be detected by the eye- Can travel in a vacuum and in a straight line in the form of waves- A luminous object is an object that gives out its own light energy. For example, sun

and stars.

- A non luminous object is an object that does not give out its own light energy but can only reflect light. For example, mirror and metal.

8. Sound energy- Is the energy produced by a vibrating object- An object which vibrates produces a recurring movement.- The vibrating air forms sound waves.- Can be transferred through a medium but cannot travel in a vacuum.

9. Chemical energy- Is the energy stored in a chemical substance- Is found in fuels

10. Electrical energy- Is the energy produced by the flow of electric charges.

11. Nuclear energy- Is the energy stored in the nucleus of an atom.- Known as atomic energy.

12. Mechanical energy- Is produced when a machine or object changes its position.- Known as energy of motion- Is composed of kinetic energy and potential energy

13. Solar energy- Is produced during the process of nuclear fusion in the sun’s core

Source of energy

Types of energy sources on Earth

a.) Fossil fuelsb.) Biomass fuelsc.) Radioactive substancesd.) Mechanical sourcese.) Geothermal sourcesf.) Solar energy

Energy sources DetailsFossil fuel Formed from remains of plant and

animals buried in the ground and which had decomposed million of years ago

Examples:- Coals- Petroleum- Natural gas

Formation of petroleum and natural gas Formed from remains of animals and plants that had sank to the bottom of

the sea and was buried there for millions of years. The decomposed animals and plants combine with sand and earth in the sea bed form shale while the remains turn into petroleum and natural gas. Normally petroleum is found below the layer of natural gas because petroleum is denser than natural gas.

Biomass fuels Are obtained from decomposed organisms such as plants and animals. Decomposed plants and animals produce methane gas and alcohol which then become fuel sources.

Radioactive substances Uranium is a common energy source used in nuclear power stations. Uranium is split into two lighter elements in the process of nuclear fission.

Mechanical sources Are natural sources of energy such as wind, water, and wave.

Are renewable energy sourceGeothermal sources Comes from heat in the inside of the

EarthSun (solar energy) Is the primary source of energy on

Earth Can be harnessed and used to

generate electrical energy

Heat

1. Heat is a form of energy which flows from a region of high temperature to another region of lower temperature.

2. Heat can travel through solids, liquids, gas, and even vacuum.3. SI Unit for heat is joule (J)4. Temperature is a physical quantity which refers to the degree of hotness or coldness of

a matter. 5. SI Unit for temperature is Kelvin (K) 6. The hotter a body, the higher is its temperature. The colder a body, the lower is its

temperature.7. The more the energy contained in an object, the higher the temperature of the object.8. Heat capacity is the quantity of heat energy contained in a matter. Is properties are:

- Dependent on the type of volume, mass of volume, and the temperature of matter- At the same temperature, a larger matter has more heat content- With the same volume, a hotter matter has higher heat content

Expansion and contraction of matter

1. Matter absorbs heat when heated and expels heat when cooled.2. When heated:

a.) Particles of matter absorb heat energy and change it into kinetic energy. Kinetic energy causes particles to vibrate faster

b.) This vibration causes the particles to move further apart. Therefore, the size and volume of matter will increase.

3. When cooled:a.) Particles of matter vibrate less and their speed also decreasesb.) Distance between the particles reduces. This means that the size and volume of

matter also decreases.

Heat flow and conduction

1. Heat is a form of energy possessed by a matter2. Heat flow in three ways :

a.) Conduction- Is the flow of heat through a solid due to a difference in temperature throughout

the solidb.) Convection- Is the process of flow of heat in a fluidc.) Radiation- Is known as radiant heat-- Is a process of energy flow through infrared waves which move in straight line

Effect of heat on matter

Melting

1. Melting is a process by which a solid changes into a liquid2. A solid melts into a liquid when heated3. When a solid is heated, the particles absorb heat energy4. At the melting point, particles vibrate most forcefully until they break away from their

fixed positions.

Freezing

1. Freezing is a process by which a liquid changes into a solid2. At freezing point, the particles no longer move freely

Boiling

1. Boiling is a process of a liquid changes into a gas2. At the boiling point, the liquid move speedily and freely.

Condensation

1. Condensation is the process of a gas changing into a liquid2. As gas particles move slower and closer together, the liquid will be formed.

Evaporation

1. Evaporation is a process of changes of a liquid into gas at any temperature.2. Factors which influence the rate of evaporation:

a.) Temperature of liquid :- The higher the temperature of the liquid, the faster the liquid evaporatesb.) Air moisture in the surrounding of the liquid:- The lower the humidity, the faster the liquid evaporatesc.) Exposed area of the liquid surface:- The wider the liquid surface area, the faster the liquid evaporates

Sublimation

1. Sublimation is the conversion process of a solid directly to gas without melting.2. In this process, the particles of a solid absorb heat energy. When enough energy is

absorbed, the particles separate to form gas.

Absorbing and giving out heat

1. The ability of an object to absorb or radiate heat depends on the surface nature and the surrounding temperature of the object.

2. Objects with opaque (black) and rough surface are good heat absorbers and radiators.

3. Objects with burnished (shiny) and smooth surfaces are poor heat absorbers and radiators.

4. Hotter objects are better heat radiators than cold objects.