expressnotes sc (f1)1st.pdf
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All Rights Reserved ©2012 Ng Chee Kin
Written By
Ng Chee KinB.Sc.(Hons.), MBA
[email protected]@blogspot.com.au
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CHAPTER 1
Introduction to Science
1.1 What is Science?
1 Science is a systematic study of nature and itseffects on us and the environment.
2 Natural phenomena are events that happennaturally around us.
3 Science can be divided into many fields suchas: Biology, physics, chemistry, geology,astronomy and meteorology.
4 Science-based careers are occupations that are based on science, for example: Life science –doctor, nurse, dietician, botanist, zookeeper;earth science – environmental scientist,meteorologist, geologist, mineralogist,volcanologist; and physical science – physicist,chemist, engineer, architect, and radiologist.
1.2 A Science Laboratory
1 It is a room or a building where scientificinvestigations are carried out.
2 We must obey safety rules and precautionswhen working in a science laboratory.
3 Common laboratory apparatus:
Test-tube Boiling tube
Beaker Filter funnel
Bell jar Gas jar
Flat-bottomed flask Round-bottomed flask
Flat-bottomed flask Conical flask
Measuring cylinder
Water trough Tripod stand
Evaporating dish
Test tube rack
Test tube holder Crucible tongs
Dropper Eureka can
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4 Hazard warning symbols:
Highly flammable
Examples:Ethanol, petrol
Explosive
Examples:Sodium, potassium
Corrosive
Examples:Concentratedhydrochloric acid,sodium hydroxide
Poisonous/toxic
Examples:Lead, mercury
Irritant
Examples:Chlorine, chloroform
Highly flammable
Examples:Ethanol, petrol
1.3 The Steps in a Scientific Investigation
(1) Identifying the problem
(2) Forming a hypothesis
(3) Planning the experiment
(4) Controlling variables
(5) Collecting data
(6) Analysing and interpreting data
(7) Drawing a conclusion
(8) Writing a report
1.4 Physical Quantities and Their Units
1 Physical quantities and their s1 units:
Physicalquantities
SI unitsUnit
symbols
length metre m
mass kilogram kg
time second s
temperature kelvin K
electric current ampere A
1.5 Weight and Mass
1 The weight of an object is the pull of theEarth’s gravity on the object.
2 The mass of an object is the quantity of matterin the object.
1.6 Measuring Tools
Physicalquantity
Tools/methodUnits
and theirrelationship
Length ofstraight lines
Metre rule,ruler, calipers(internal &
1 cm = 10 mm1 m = 100 cm1 km = 1000 m
external),micrometer,verniercalipers
Length of
curves
String
and ruler,opisometer
Area ofregularshapes
Mathematicalformulae,graph paper
1 cm2 = 100 mm2
1 m2 = 10 000 cm2
1 km2 = 1 000 000 m2
Area ofirregularshapes
Estimationusing graphpaper
Volume of
liquids
Measuring
cylinder,pipette, burette
1 ml = 1 cm3
1 l = 1 000 cm3
1 m3 = 1 000 000 cm3
Volume ofregular-shaped solids
Mathematicalformulae,waterdisplacementmethod(Eureka canor measuring
cylinder filledwith water) 1 m3 = 1 000 000 cm3
Volume ofirregular-shaped solids
Waterdisplacementmethod(usingEureka canor measuringcylinder filledwith water)
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1.7 The Importance of Standard Units
1 Standard unit improves internationalcommunications.
2 They also ensure the physical quantities aremeasured accurately and consistently.
CHAPTER 2
Cell As a Unit of Life
2.1 What is a Cell?
1 A cell is the basic unit of life. 2 Its function is to carry out life processes.
Protoplasm Cell membrane
Nucleus Cytoplasm
Cell
Animal cells Plant cells
Irregular in shape Regular in shape
No cell wall Have cell wall
No chloroplasts Have chloroplasts
Mostly no vacuoles Have large vacuoles
3 The functions of cell structures:
Structure Function
Nucleus Controls all cell activities
Cytoplasm A place where chemicalprocesses take place
Cell membrane Controls flow of materialsin and out of cell
Cell wall Gives shape to the cell
(e)
(f)
2 A multicellular organism has many cells. (a) (b)
(c)
2.3 Cell Organisation in the Human Body
1 Organisation of cell:
Cell (simple)
↓
Tissue
↓
Organ
↓
System
↓
Organism (complex)
nucleus
Chloroplast Carries outphotosynthesis
Vacuoles Stores water anddissolved materials
4 A microscope is used to study the general
structure of a cell.
2.2 Unicellular and Multicellular Organisms
1 A unicellular organism has one cell only.
(a)
(b)
(c)
(d)
Pleurococcus
Amoebapseudopodium
nucleus
Chlamydomonas
Paramecium
chloroplast
cilium
Euglena
Yeast
nucleus
bud
Chondrus
Hydra
Spirogyra
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2 Examples of cell: (a) Nerve cell
(b) Red blood cell
(c) Epithelial cell
(d) Bone cell
3 Examples of tissue: (a) Connective tissue
(b) Mucsle tissue
(c) Nerve tissue
(d) Epithelial tissue
4 Examples of system:
(a) (b)
(c) (d)
(e) (f)
BrainTongue
KidneyEye
StomachLungs
5 Examples of system:
2.4 The Human Being – A Complex Organism
1 A human being is a complex multicellularorganism because the cells are organized intotissues, organs and systems.
2 Cell specialisation helps to divide bodyfunctions among the different types of cells.
3 Cell specialisation and cell organisationensure the life processes are carried outeffectively.
Pituitarygland
Testis(male)
Ovary(female)
Adrenalgland
Thyroidgland
Female
Oviduct orFallopian tube
Ovary
UterusVagina
Male
Spermduct
Urethra
penis
Testis
Sexglands
Endocrine system
Nose
Trachea Bronchus
Lungs
Skin
Liver
Kidney
Urinary bladder
Respiratory system Excretory system
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CHAPTER 3
Matter
3.1 What is Matter?
1 Matter is everything that has mass and
occupies space. 2 Examples of matter are wood, air, water, soiland living things.
3.2 The States of Matter
1 Matter exists in three states: solid, liquid andgas.
2 Matter changes its state when it is heated orcooled.
3 The kinetic theory of matter states that matterconsists of tiny and discrete particles.
4 Characteristics of state matter:Characteristic Solid Liquid Gas
Arrangementof particles
Closelypacked
Further apart Very farapart
Spaces betweenparticles
Very small Large Very large
Movement ofparticles
No freemovement,vibrateabout a fixedposition
Move freely,collide withone another
Movefreely, veryrapidly andrandomly
Density High Medium Low
Shape Definiteshape
No definiteshape
No definiteshape
Volume Definitevolume
Definitevolume
No definitevolume
Examples Soil, wood,most metals
Water,mercury(a type ofmetal)
Air
3.3 The Concept of Density
1 Density is defined as mass per unit volume ofa substance.
MassDensity = ————
Volume
2 The unit of density is gram per cubiccentimeter (g/cm3).
3 The buoyancy of a substance is affected by itsdensity.
4 Buoyancy (or flotation) refers to the abilityof a substance to float or sink in another
substance. 5 A lower density substance will float on a
higher density liquid. 6 On the other hand, a higher density substance
will sink in a lower density liquid.
3.4 The Properties of Matter and Their Applicationin Everyday Life
Matter Example Applications
Solid Iron, steel To construct buildings, bridges and vehicles,make cooking utensils
Wood To build bridges adhouses, making furniture
Plastic To make toys, componentsin vehicles
Liquid Mercury To make thermometer,hydrometer
Water To make drinks, cooking,washing and cleaning
Gas Air To fill buoy, rise hotair balloons, make asubmarine sink or float
CHAPTER 4
The Variety of Resources on Earth
4.1 The Various Resources on Earth
1 The basic resources needed for life on Earthare:
Basic
resource
ImportanceUseful
substancesAir Needed for
respiration andcombustion
Oxygen,nitrogen,carbondioxide
Carbon dioxideis needed forphotosynthesis
Water Needed to supportthe functions of the body systems
Fresh water
Soil Contains air, water,minerals and organicsubstances which areneeded to supportliving things
Humus
Minerals Minerals such asmetals are usedto make usefulproducts andconstruct buildings
Metals
water (1.00 g/cm3)
zinc (7.10 g/cm3)
cork (0.24 g/cm3)
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Fossilfuels
Used to produceenergy in powerplants, factories,vehicles, machinesand to make plastics
Coal,petroleum,natural gases
Living
things
They are sources
of food, buildingmaterials, clothesand fuel
Meat, skin,
carcasses,silk, milk
4.2 Elements, Compounds and Mixtures
Comparing elements, compounds and mixtures
Aspect Element Compound Mixture
Appearance
Definition It is thesimplessubstance
It is madeup of twoor moresubstanceswhich arechemicallycombined
It is madeup of twoor moresubstanceswhichare notchemicallycombined
Composition Only
consists ofone typeof particle
Can consist
of one ormore thanone type ofparticle
Separationmethod
Cannot beseparated
by anyprocesses
Can beseparated
by chemica lmeans only,such aselectrolysis
Can beseparated
byphysicalmeans,such asfiltration
Examples Iron,hydrogen,oxygen,helium,carbon,mercury
Naphthalene,sugar, rubber,table salt,water
Soil, air,dessert
Comparing metals and non-metals
Physicalproperties
Metals Non-metals
Surfaceappearance
Shiny Dull
Brittlenessand hardness
Ductile (can be pulled intostrands) andhard
Brittle (can break easily)and soft
Malleability(ability to beshaped)
Malleable Non-malleable
Conductivityof heat
Goodconductor ofheat
Poorconductor ofheat
Conductivityof electricity
Goodconductor ofelectricity
Poorconductor ofelectricity
Melting point High LowBoiling point High Low
Density High Low
Physical methods to separate components of a mixture
Physicalproperties
Metals Non-metals
Surfaceappearance
Shiny Dull
Brittleness andhardness
Ductile (can be pulledinto strands)and hard
Brittle (can break easily)and soft
Malleability(ability to be
shaped)
Malleable Non-malleable
Conductivity ofheat
Goodconductor ofheat
Poorconductor ofheat
Conductivity ofelectricity
Goodconductor ofelectricity
Poorconductor ofelectricity
Melting point High Low
Boiling point High Low
Density High Low
Comparing the Properties of Compounds and Mixtures
Aspect Compounds Mixtures
(a) Method ofseparation
By chemicalreactions.
By physicalmeans.
(b) Formationof a newsubstance
A newsubstance isformed
No newsubstance isformed
(c) Conversion of
energy
Heat is
released orabsorbedwhen acompound isformed
No heat is
released orabsorbedwhen amixture isformed
(d) Characteristicof the originalcomponents
Thecharacteristicsof the originalcomponentsare no longermaintained
Thecharacteristicsof the originalcomponentsaremaintained
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(e) Identificationof the originalcomponents
The originalcomponentscannot beidentifiedeasily
The originalcomponentscan beidentifiedeasily
(f) Ratio of
components
Components
are combinedin a specificratio
Components
are formedwithout afixed ratio
4.3 To Appreciate the Importance of Earth’sResources
1 Preservation of resources is the act of keepingthe resources in their original state.
2 Conservation of resources is the responsibleuse and management of natural resources toprevent loss, waste or damage.
3 Preservation and conservation of Earth’sresources are important to:(a) prevent extinction of animal and plant
species(b) prevent depletion of natural resources
such as fossil fuels and minerals(c) prevent the pollution of air and water(d) ensure the basic needs of humans are not
threatened(e) ensure the natural resources will be
available for future generations
CHAPTER 5
The Air Aroun Us
5.1 The Composition of Air
Nitrogen (78%) Oxygen (21%)
Inert gases + watervapour + dust +microorganisms (0.97%)
Carbon dioxide(0.03%)
Experiments to show the properties of air
1 Air consists of about 20% of oxygen.
Water fills up – ofgas jar, showingthat about 20% ofthe volume of airconsists of oxygen
2 Air contains water vapour.
Beginning ofexperiment
End ofexperiment
Cork
Test tube
Ice
Water
Liquid on theouter wall ofthe test tube
3 Air contains microorganisms.
4 Air contains dust particles.
Glass slide
Sticky surfacefacing upDust particles
Glass slide
Dustparticles
5.2 The Properties of Oxygen and Carbon Dioxide
Properties OxygenCarbondioxide
Colour Colourless Colourless
Odour (smell) Odourless Odourless
Solubility inwater
Slightlysoluble
Slightlysoluble
Solubilityin sodiumhydroxide
Not soluble Very soluble(to formsodiumcarbonate)
Effect on limewater
No effect Lime waterturns cloudy
Supporting
combustion
Supports
combustion.
• A glowingsplinterrelights
• A burningsplinter burns more brightly
Does not
supportcombustion.• A glowing
splinterrelights
• A burningsplinter burns more brightly
pH Neutral
• Has noeffect onmoist blueand redlitmuspapers
• Has noeffect onhydrogencarbonateindicator
Acidic
• Turnsmoist bluelitmuspaper tored
• Turns redhydrogencarbonateindicator toyellow
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5.3 Oxygen is Needed for Respiration
1 Oxygen is needed for respiration to produceenergy.
2 The composition of inhaled and exhaled air:
GasComposition (%)
Inhaled air Exhaled airNitrogen 78 78
Oxygen 21 16
Carbondioxide
0.03 4
Inert gases 0.97 0.97
Watervapour
Less More
5.4 Oxygen is Needed for Combustion
1 Combustion is a process that requires oxygen,heat and fuel.
2 Combustion of carbon (such as charcoal):
Carbon + Oxygen → Carbon dioxide 3 Combustion of hydrocarbon (such as
kerosene):
Hydrocarbon + Oxygen → Carbon dioxide + Water
5.5 Air Pollution
1 Air pollution is caused by the pollutants inthe air.
2 Air pollutants are harmful substances thatare added to the air.
3 The effects of air pollution on human beings:• Lung cancers (caused by asbestos,
sulphur dioxide)• Brain damage in children (caused by lead
particles, carbon monoxide)
• Bronchitis, pneumonia (caused bysulphur dioxide)
• Death (caused by carbon monoxide) 4 The effects of air pollution on the
environment:• Acid rain (caused by sulphur dioxide)• Thinning of the ozone layer (caused by
CFC)• Greenhouse effect (caused by carbon
dioxide)• Haze (caused by dust particles, soot)
5.6 The Importance of Keeping the Air Clean
1 We can keep the air clean by practising thefollowing:
• Using less CFC based products, such asaerosols.
• Recycling and reducing wastes• Using unleaded petrol
• Using public transport or sharing vehicles(car pooling)
• Installing catalytic converters to motorvehicles
2 Cigarette smoke contains tar, nicotine andcarbon monoxide which are harmful tohumans.
CHAPTER 6
Sources of Energy
6.1 The Various Forms and Sources of Energy
1 Energy is an ability to do work.
2 The SI unit for energy is joule (J).
3 Forms of energy: Potential, electrical, kinetic,chemical, heat, nuclear, light, mechanical,sound
Energy Characteristics Examples
Potential(stored energy)
Energy storedin an object dueto its position orcondition.
• A stretchedsling-shot
• A rock on acliff
• A
compressedspring
• A wound upalarm clock
Kinetic(workingenergy)
• Energy thatis foundin movingobjects.
• A moving bus
• A swingingpendulum
• A rotatingceiling fan
• A flyingaeroplane
Heat(workingenergy)
• Energy thatis released
by hotobjects.
• A burningcandle
• A boilingwater
• The hot Sun• A hot iron
Light(workingenergy)
• Energy thatis produced
by glowing
objects.
• A shiningstar
• A glowing
light bulb• A burning
campfire• A switched
on torch
Sound(workingenergy)
• Energy thatis produced
by vibratingobjects.
• A beatingdrum
• A personsinging
• A blowingwhistle
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• A ringingtelephone
Electrical(workingenergy)
• Energy thatis produced
by flowing
electricalcurrent(electricity).
• An electriciron
• An electric
heater
Chemical(stored energy)
• Energy thatis stored ina substancethat can be
burnt.
• Food• Fossil fuels
(such asnatural gas,coal andpetrol)
• Wood
Nuclear(stored energy)
• Energy thatis produced
by atomsthat are
brokendown(throughnuclearfission) orcombined(throughnuclearfusion).
• Explosionof an atomic
bomb• The
explosionon the Sun’ssurface
Mechanical(combinationof workingand storedenergy)
• Energy thatis posessed
by an objectthat has
both kineticenergy andpotentialenergy.
• A car isdriven up ahill
• A pendulumswings backand forth
4 Sources of energy:
Sources ofenergy
Examples Uses
Fossi l fue ls • Coal• Petroleum• Natural
gas
• To generateelectricity inpower plants
• As the mainfuel for vehiclesand machines
Wind • Movingair
• To move asailboat
• To turn awindmill forpumping waterand grind corn
• To generate
electricity inwind farms
Water(hydro)
• Rain fall • To generatehydroelectricity
Sun(solar)
• The Su n • To generateelectricity (solarcells and solarpanels collectsolar energyand convertit electrical
energy)• To enable
photosynthesisin green plants.
Radioactivesubstances
• Uranium• Plutonium
• To producenuclear energy.
• To produceelectrical energyin submarinesand warships
Geothermal • Geysers• Hot
springs• Volcanoes
• To producegeothermalenergy thatcan be usedto generateelectricity
5 Energy changes from one form to another. For
example:
Situation Energy change
A marble rollsdown a slope
Potential energy→ Kinetic energy
Winding up springof a toy car
Kinetic energy→ Potential energy
Burning a candle Chemical energy→Heat + Light energy
Beating a drum Kinetic energy→ Sound energy
Switching on a fan Electrical energy→ kinetic energy
An explodingatomic bomb
Nuclear energy→ Heat + Light +Sound energy
6 The Sun is the primary source of energy.
6.2 Renewable and Non-Renewable Energy
Sources 1 Comparing renewable and non-renewable
energy sources:
Renewable Energy(energy sources thatcan be reused andwill never run out)
Non-renewable Energy(energy sources that will be used up one day andcannot be replaced)
• Solar energy(from the Sun)
• Fossil fuels (suchas natural gas,petroleum and coal)
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• Hydroelectricity(from flowingwater)
• Biomass energy(from plants)
• Wind energy
(from wind)• Geothermalenergy (from theEarth)
• Nuclear energy(from plutonium)
2 Conservation and efficient use of energy:(a) Use energy efficient equipment, such as
fluorescent lights(b) Use public transport, such as buses and
light-rail transit (LRT)(c) Practice car-pooling to work
6.3 The Importance of Conserving Energy Sources
1 Conserving non-renewable resourceswill make them last longer for the futuregenerations.
CHAPTER 7
Heat
7.1 Heat as a Form of Energy
1 Heat is a form of energy 2 Heat can be produced from:
(a) kinetic energy, such as rubbing twoobjects together
(b) chemical energy, such as burning fossilfuels
(c) electrical energy, such as lighting anelectric bulb
(d) nuclear energy, such as nuclear fission inthe Sun
3 Comparing heat and temperature:
Aspect Heat Temperature
Definitionon
A form ofenergy
Degree ofhotness of anobject
SI Unit joule (J) kelvin (K).Normally we
use degreesCelsius (°C)
How it isproduced
• Kineticenergy(such asrubbinghands)
• Chemicalenergy(such as burning
fossil fuels)• Electrical
energy(such aslighting alight bulb)
• Nuclearenergy(such asnuclearfission in
the Sun)
• Supplyingheat energyto an object(causingtemperatureto increase)
• Removingheat froman object
(causingtemperatureto decrease)
Effect • Causesmatter toexpand orcontract
• Caussmatter tochangefrom onestate toanother
• Causesmatter to become hotor cold
• Causesheat to flowfrom a hotregion to acold region
Affected by • Volume-the biggerthevolume,the morethe heat
• Amount ofheat- themore the heatenergy issupplied, thehigher the
temperatureDifference
P containsmore heatthan Q
P and Q havethe sametemperature
7.2 The Effects of Heat Flow on Matter
1 Heat changes the volume of matter. 2 When heated, the volume of matter increases.
Hence, matter expands. 3 When cooled, the volume of matter decreases.
Hence, matter contracts. 4 Heat flows from a hot region to a cold region
in three ways:(a) conduction, occurs in solids(b) convection, occurs in fluids (such as
liquids and gases)(c) radiation, does not require a medium
7.3 Effects of Heat on Matter
ProcessChange of state
of matterHeat flow
Melting Solid→ Liquid Heat isabsorbed
Freezing Liquid→ S olid Heat isreleased
P Q P Q
100°C100°C
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Boiling Liquid→ Gas Heat isabsorbed
Condensation Gas→ liquid Heat isreleased
Evaporation Liquid→ Gas Heat isabsorbed
Sublimation Solid→ Gas
Gas→ Solid Heat isabsorbedHeat isreleased
7.4 Application of Contraction and Expansion of
Matter
1 Application of expansion and contraction ofmatter:
(a) Mercury or alcohol in thermometers (b) Bimetallic strip in thermostats (c) Bimetallic strip in fire alarms (d) Gaps in railway tracks and bridges (e) Telephone wires (f) Metal pipes carrying hot water and oil
7.5 Absorbing and Giving Out Heat
1 Objects that absorb heat are called heatabsorber.
2 Objects that give out heat are called heatradiator.
3 Dark, dull objects are good heat absorber andgood heat radiator.
4 White, shiny surfaces are poor heat absorberand poor heat radiator.
7.6 The Benefits of Heat Flow
1 Application of heat flow via conduction:(a) Heat is used for cooking food with
cooking utencil(b) Heat is used to melt metal for making
jewellery and equipment
2. Applications of heat flow via convection:(a) Convection currents improve the aircirculation and keeps the buildings cool
(b) Convection currents cool the Earth’ssurface through sea breeze and land breeze.
3 Applications of heat flow via radiation:(a) Heat flow by radiation is used to dry
laundry(b) The heat from the Sun keeps the Earth
and our body warm
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