SlideShare utilise les cookies pour améliorer les fonctionnalités et les performances, et également pour vous montrer des publicités pertinentes. Si vous continuez à naviguer sur ce site, vous acceptez l’utilisation de cookies. Consultez nos Conditions d’utilisation et notre Politique de confidentialité.
SlideShare utilise les cookies pour améliorer les fonctionnalités et les performances, et également pour vous montrer des publicités pertinentes. Si vous continuez à naviguer sur ce site, vous acceptez l’utilisation de cookies. Consultez notre Politique de confidentialité et nos Conditions d’utilisation pour en savoir plus.
•We want to know why and how all these thingshappen. We search for an answers. Thus, the study ofscience gives us answers.•Science is the systematic study of nature and how itaffects us and the environment.•The information produced from the study of science isknown as scientific knowledge.•Scientific knowledge develops as new scientificdiscoveries are discovered every day.
•Using scientific knowledge, we invent many usefuldevices such as light bulbs, telephones andcomputers. The application of scientific knowledgefor the use of mankind is called technology.•We use technology almost every aspect of lifethus making science part of our every day life.
Importance of Science•Science plays important roles in our daily life.a.Science helps us to understand ourselves.Knowing how our body works, helps us to takebetter care of our health.b.Science also helps us to understand ourenvironment. This helps us to improve thequality of our environment and conserve it forour future generation.c.Science makes our life more comfortable. Weinvent various machines to help us to work fasterand more efficiently.
Use and benefits of science in daily life•Facilities such as electricity and tap water make life easier andmore comfortable.•Various appliances such as washing machine, microwave ovenand vacuum help us to do our housework faster.In Homes
Communication•Communication is easier and faster with the use of television,telephone, mobile phone, facsimile and computer.•Global communication is now possible with the use ofcommunication satellites, e-mail and the internet.
Transportation•Transportation is easier, faster and more comfortable.•Modern public transports such as commuter trains and lightrail transit reduce congestion in cities.•The design of better roads and highways increases the safety ofusers.
Construction•Buildings and structures are now built with strong materialssuch as steel, concrete and reinforced glass.•Powerful machinery such as cranes, tractors and bulldozers areusually used in construction works.
Agriculture•Machines are used to carry out heavy and difficult taskssuch as ploughing and harvesting.•Plant breeding, new agricultural techniques, fertilizers andinsecticides contribute greatly in increasing the world’sagricultural products.
Medicine•More diseases can now be cured with the discoveries of newdrugs, vaccines, antibiotics and the invention of better surgerytechniques and equipment.•Diseases can be diagnosed and detected earlier with varioustests and devices such as X-ray machine and ultrasoundscanning device.
Careers in science•Science offers various career opportunitiesaccording to one’s area of interest.a.Doctor – a person has been trained in andpractises medicinal science.b. Veterinarian – an animal doctor.c. Pharmacist – a person who dispensesmedical drugs and advise their uses.
d. Engineer – a skilled person who designs, buildsor maintains engines, buildings, bridges orroads.e. Architect – a person who design buildings andadvises on their construction.f. Chemist – a person trained in chemistry.
•Science is divided into a number of areas of study:a. Biology – the study of life.b. Physics – the study of matter, energy, force andmotion.c. Chemistry – the study of composition andchemical properties of substance.d. Astronomy – the study of planets and stars inthe Earth.e. Geology – the study of rocks, minerals and thestructure of the universe.f. Meteorology – the study of weather and climate.g. Biochemistry – the study of chemical process inliving organisms.
Science Laboratory•The place where a scientist works is called laboratory.•Students carry out scientific investigations orexperiments during science lessons in sciencelaboratories.•There are rules and safety precautions that must befollowed by the students in order to avoid accidents.
Rules and Safety PrecautionsNever enter the laboratory unless a teacher ispresent.Do not eat, drink or taste chemicals.Always follow the teacher’s instructions.Never touch chemicals with your bare hands. Use aspatula.Read a label on a reagent bottle before using itscontent.Turn off the Bunsen burner after use.Do not pour back any unused chemical into its bottle
Do not throw solid wastes into the sink.Wash and keep all apparatus after use.Do not run or play in the laboratory.Do not test anything without the teacher’spermission.Report any breakages to the teacher.Keep the bench clean and tidy.
•We need to use apparatus to carry out experimentsTest tubeTo hold a small amountsof liquid or chemical.Boiling tubeFor heating small amountsof liquid.
BeakerConical Flask Flat – BottomedFlaskTo hold bigger amounts of liquids or chemicals.
Retort standTo hold or supportapparatus.BuretteTo measure small volumesof liquid accurately.
Bunsen burnerTo provide a flame forheating.Filter funnelUsed together with a filterpaper to filter mixtures ofsolids and liquids.
Wire gauzeTo support apparatus andensure even heating.Tripod standTo support apparatusduring heating.
CrucibleTo hold solids for strongheating.Evaporating dishTo hold liquids forevaporating.
SpatulaTo transfer small amountsof liquids.Test tube holderTo hold a test tube duringheating.
a. A Bunsen burner is used in the laboratory to heatsubstance.b. The Bunsen burner has an air – hole. The air –hole can be opened or closed by turning thecollar.c. When the air – hole is opened, the Bunsenburner gives a blue flame. This is called a non –luminous flame. The flame is very hot becausethe gas is burned completely.d. When the air – hole is closed. The burner gives ayellow flame. This flame is easier to see and it iscalled luminous flame. This flame is less hot andproduce a lot of black soot because the gas is notburned completely.
e. The correct way to light up a Bunsen burner isas follows:•Close the air – hole by turning the collar.•Hold a lighted match or a lighter at the top of thebarrel.•Turn on the gas slowly. A yellow or luminousflame will be obtained.•Open the air – hole to obtain a blue or non –luminous flame.
f. To avoid accidents when using a Bunseenburner, the following precautions should betaken.•Use a lighter or a match to light up a Bunsenburner instead of a burning paper.•We must light up the match before turning onthe gas.•When heating a test tube, hold the test tube atan angle of 45 degrees. Use a test – tube holderand do not point the mouth of the test tube toyourself of your friends.
•Do not heat flammable substances likealcohol directly.•When not using the Bunsen burnertemporarily, close the air – hole to obtainthe yellow flame because this flame iseasily seen. Remember to turn off the gasafter using the burner.
The correct way to hold a testtube during heating.
•Some substances in the laboratory arehazardous or dangerous.•Hazard warning symbols are placed on labelsof bottles or containers of hazardous substancesto show the danger of the substances.•As young scientists, you must be able torecognize the symbols and know how to handlethe substances properly.
Flammable orinflammable•Easily catchesfire and burns•Organicsolventssuch asethanol,petrol orkerosene•Keep awayfromfire orheatsources.Toxic /poisonous•Causes deathor harm to thebody ifabsorbedthrough theskin, swallowedor inhaled.•Mercury,chloroform,lead,benzene,bromine,sodiumcyanide,hydrogensulphide•Do notinhale,touch ortaste thesubstances.•Keep in alockedcupboard.
Corrosive•Causes damageto the skin oreyes uponcontact•Concentratedacids andalkalis,bromine,hydrogenperoxide.•Avoidcontact withskin oreyes.•Spill on bodyparts shouldbe washedaway quicklyunderrunningwaterIrritant / harmful•Irritates causes(itchiness andrashes) skin,eyes andrespiratorysystem•Ammoniasolution,chloroform,dilute acidsand alkalis•Spill on body partsshould be washeswith a lot of water.
Radioactive•Gives outradiation thatcan causecancerordestroy bodilytissues.•Uranium,plutonium, radium.•Keep in speciallead containers.