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Science
The study of phenomena and events in Nature through systematic observation and experimentation
The branches of science
Physics, chemistry, biology, astronomy, geology, medicine
Major natural resources
water, living things, fossil fuels, air, metal ores
Renewable resources
Resources that can be replenished continuously in Nature and will not be used up
Examples of renewable resources
Plants, animals, water, air
Non-renewable resources
Resources that cannot be replenished in a short time once they are used up. Their supply is limited
Examples of non-renewable resources
Fossil fuels, metal ores
Natural resources that are seriously affected by pollution
Water and air
What problems cannot be solved by using scientific knowledge?
Relationships, ethics, wars
Scientific knowledge is subject to ()
change
Steps in a scientific investigation
Observe, form a hypothesis, design and do experiments, analyse, draw a conclusion
Science process skills
observing, classifying, inferring, communicating
Types of scientific investigations
Fair tests, classifying, pattern seeking, model building
Independant variable
The only variable that is changed
dependant variable
The variable to be measured
controlled variables
Variables that are kept the same
Classifying
Comparing the similarities and differences between objects, and sorting those with similarities into groups
Pattern seeking
Observing and recording natural phenomena and trying to find a pattern
Model building
Represent objects that are too small or too big to see
Laboratory safety equipment (4)
Safety goggles, protective gloves, fire blanket, sand bucket
Potential dangers in the laboratory (4)
Should tie up long hair, should wear safety goggles, should not eat or drink, should not leave Bunsen flame unattended
Hazard warning symbols
Flammable, corrosive, explosive, toxic, harmful or irritant
Flammable
Keep away from heat and flame
Corrosive
Wear safety goggles and protective gloves when handling the chemical. Store in a well ventilated room
Explosive
Keep away from heat and flame. Avoid shock
Toxic, harmful, irritant
Avoid breathing in the vapour of the chemical. Wear safety goggles and protective gloves when handling the chemical. Wash your hands thoroughly after handling the chemical
Cuts
Clean the wound with water and apply a dressing to it
Heat burns or chemical burns
Place the affected area under slow running water
Chemicals got into the eyes
Wash the eyes with distilled water from an eye wash bottle
Glass breakage
Clean up broken pieces of glass and dispose of them in a broken glass container
Gas leakage
Turn off the gas supply and open all windows and doors
Fires
Keep calm and report to your teacher at once
Fire triangle
Fuel, oxygen and a high temperature
Using fire beaters
Stop the supply of oxygen
Spraying with water
Lowers the temperature
Cutting down trees
Remove the fuel
How should we read the scale when measuring the length of an object with a ruler
From vertically above
Meniscus
The curved surface of liquid in the measuring cylinder
How should we take an accurate reading of the liquid in the measuring cylinder?
At the bottom of the meniscus
What can we use to measure the mass of an object?
A balance
What can we use to measure the temperature of an object?
Thermometer
How should we take an accurate reading of the thermometer?
Our eyes should be at the same level as the liquid level
What do we usually use to measure time?
A stopwatch
Why do we often repeat the measurement several times and then calculate an average value?
To reduce errors
Ways to transfer solutions
Pouring and using a dropper
Different methods to mix solutions well (2)
Use a glass rod to stir, gently shake the test tube
Luminous flame
Air hole is closed, irregular shape, yellow in colour, lower temperature, quiet
Non-luminous flame
Air hole is open, regular shape, blue in colour, higher temperature, noisy
Strike back
Air hole is fully open, green in colour, high temperature, hissing sound
Physical states of water
Solid, liquid, gas
Solid
Ice
Liquid
Water
Gas
Water vapour
Melting
The change from solid state to liquid state
Melting takes place at a () temperature, what is it called?
fixed, melting point
Melting point
0 degrees Celsius
Does the temperature change during the process of melting?
No
When ice melts, does it absorbs or releases energy?
Absorbs
Freezing
The change from liquid state to solid state
Freezing takes place at a () temperature, what is it called?
fixed, freezing point
Does the temperature change during the process of freezing?
No
The freezing point of water
0 degrees Celsius
When ice freezes, does it absorbs or releases energy?
Releases
Boiling and Evaporation
The change from liquid state to gas state
Boiling takes place at a () temperature, what is it called?
fixed, boiling point
Boiling point of water
100 degrees Celsius
What happens when water is heated to its boiling point?
It changes to steam
Does the temperature change during the process of boiling?
No
When water boils, does it absorbs or releases energy?
Absorbs
Evaporation takes place at () temperature
Any
What happens when water evaporates?
It changes into water vapour
When water evaporates, does it absorbs or releases energy?
Absorbs
Condesation
The change from gas state to liquid state
When does condensation happen?
When water vapour in air comes into contact with cold surfaces
What happens when water vapour in air condenses into water?
Water droplets are formed on the surfaces
When water vapour or steam condenses into water, does it absorbs or releases energy?
Releases
Which two changes of state in water are in the water cycle?
Evaporation and condensation
When does the rate of evaporation increase?
The temperature is higher, the humidity is lower, there is more airflow and the surface area exposed is larger
Solution
When a substance dissolves in a liquid
Solute
The substance that dissolves
Solvent
The liquid in which the substance dissolves
Water
Universal solvent
Soluble
Can be dissolved
Insoluble
Cannot be dissolved
When does the rate of dissolving increase?
The solution is stirred, the temperature of the solvent is higher, the surface area of the solute is larger
Solubility
The maximum amount of solute that can be dissolved an a fixed amount of solvent
What does the solubility of a substance in water change with?
Temperature
What does natural water contain a lot of?
Impurities
Two most common microorganisms found in natural water
Amoeba and E.coli
Methods of water purification
Sedimentation, filtration and distillation
Sedimentation
Large and heavy insoluble impurities sink to the bottom of the container and form a layer of sendiment
Commonly used filters in the laboratory
Filter columns, filter paper
What does filter paper have?
Many tiny pores
Residue
Impurities that cannot pass through the pores and are trapped by the filter paper
Filtrate
Liquid, microorganisms and soluble impurities that passes through
Distillation
The process of boiling and condensing water
What can distillation remove?
insoluble and soluble impurities and microorganisms
Methods to kill microorganisms in water
Chlorination, adding ozone and using ultraviolet light
Disadvantages of chlorination
Toxic and has an irritating smell
Advantages of ozone
Does not have an irritating smell and is more effective in killing microorganisms
Note 
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