What Is Chemistry Y CHEMISTRY Chemistry is the study of substances and the changes that happen to them Substances are things like food clothes and medicine Chemistry is very important Plastic bags and shoes with rubber soles would not exist without chemistry Fuels for cars airplanes and rockets would not exist without chemistry Chemical reactions or changes inside the human body are important They make it possible for people to think eat and breathe Chemistry is everywhere Chemicals in fertilizer helped these fruits and vegetables grow Without chemistry we would not have these clothes to keep us warm Enzymes in the girls stomachs will help them digest their food We know how our medicine works because of chemistry R T S I M E H C S I T A H W 4
CHEMISTRY In school it might seem we’ve solved all the mathematics problems already because most of the things What do elephant tusks and you do have right and wrong answers billiard balls have in common But mathematics is always growing As Before the invention of plastic elephant we learn new things and create new tusks were the main material used to make technologies we find new problems to billiard balls John Wesley Hyatt 1837 1920 solve invented celluloid a special kind of plastic in 1868 Celluloid proved to be the perfect ingredient for creating billiard balls as well as movie film Scientists learn about chemistry in The Scientific Method three ways They observe or watch substances They study substances and they do experiments They try to make substances change and then record what happens Scientists carefully plan how they learn about chemistry They often use a system called the scientific method to answer questions they might have The scientific method is very important It allows scientists to learn about how things work There are four parts to the scientific method 1 Scientists begin the scientific method by asking a question 2 They research information problem When gathering information scientists use observations to watch what they are studying very carefully They might write down or record their observations when collecting the information Scientists call this information data They also collect data by reading other scientists books and journal articles The Internet is another useful tool for gathering information about their question or W H A T I S C H E M I S T R Y 5
CHEMISTRY 4 The fourth step of the scientific method is gathering materials hypotheses in experiments and then testing the hypothesis Scientists test or try out their Scientists conduct the same experiment many times to be sure of the results Scientists often do their experiments in a laboratory A laboratory is a place where scientists conduct experiments and collect data Controlling conditions in a laboratory is easier than controlling conditions in the real world For example temperature levels are able to remain constant in a controlled setting That would be impossible to do outside of a laboratory Y R T S I M E H C S I T A H W 6 A scientist carefully records data during an experiment 3 The third step of the scientific method is making a thoughtful hypothesis is an idea or opinion based on some data or observations but not proven guess or hypothesis A Scientists formed the hypothesis that this fertilizer is what makes the plants grow big and healthy They will test their hypothesis to see if it is true
7 CHEMISTRY W H A T I S C H E M I S T R Y Chemists made sure this medicine was safe for children HOW DO SCIENTISTS LEARN ABOUT CHEMISTRY They observe or watch substances They do experiments They try to make substances change and then record what happens An experiment might show that the hypothesis is not correct For this reason scientists always perform tests for one experiment several times They call these tests trials In each trial scientists change only one thing also known as the variable New data might cause a scientist to change the hypothesis Sometimes a scientist disregards the hypothesis and starts all over Hypotheses proven true predict how things will work and can be very helpful control kuhn-TROHL to exercise restraint or direction over dominate command experiment ek-SPER-uh-ment a scientific test to try out a theory or to see the effect of something fuel FYOO-uhl something that is used as a source of heat or energy such as coal wood gasoline or natural gas observation ob-zur-VAY-shuhn the careful watching of someone or something
