Chemistry: Ch 1 Matter and Change
Golden Rod Demo Notes Welcome to Chemistry!!!!!
What is Chemistry? Activity: Insta-Snow • Observing • Asking Questions • Looking for Answers • Asking More Questions • Experimenting • More Observing • What we’re doing-playing with stuff like 8-year-olds...is the root of modern science. • Observing the world and trying to figure out what it means is the core of science. We invent theories to explain what we see, hear, and smell. • Chemistry (Science) is a process of observing, educated guessing, and testing.
Chemistry is Everywhere • Everything you hear, see, smell, taste, and touch involves chemistry and chemicals. • Chemistry is the study of matter and the changes it can undergo. • Chemistry is about composition, structure, function, and interaction of matter. • Everything has composition, structure, function, and interaction • Matter is anything that has mass and occupies space. • All matter is composed of various combinations of elements. The wonder of chemistry is that when these basic particles are combined, they make something new and unique. • Chemistry helps us understand the world around us. • Understanding the basic properties of matter and learning how to predict and explain how they change when they react to form new substances is what chemistry and chemists are all about. • Chemistry is not limited to beakers and laboratories. It is all around us, and the better we know chemistry, the better we know our world. • All other sciences (biology, physics, geology, etc) have their basis in chemistry.
Chemicals (Substances) • Matter with definite composition • Either Elements or Compounds • Elements: One type of atom • Oxygen (O2) • Ozone (O3) • Copper • Compounds: Two or more types of atoms • Sodium chloride (table salt) NaCl • Ethyl alcohol • H2O
How does this photo illustrate what chemistry is all about? • Chemical reactions of rusting/weathering/maybe a fire in the fireplace • Physical states of water • Different types of materials: glass, wood, living material, brick, snow
The Study of Matter and Change What is Matter? Anything that has mass and takes up space (volume) Stuff Not Matter Light Energy Emotions or Feelings Thoughts Electricity Sound
Submicroscopic and Macroscopic Submicroscopic Macroscopic What we observe Determined by the submicroscopic (atomic) Chemist are interested in how the atomic level determines the macroscopic • Atomic Level • What happens here determines the macroscopic
The Scientific Method • The scientific methodis a systematic approach used in scientific study, whether it is chemistry, physics, biology, or another science. • To solve problems • Not a set of rigid steps • It is an organized process used by scientists to do research, and provides methods for scientists to verify the work of others.
Observations • Gathering Information (Data) using the five senses • No trivial or unimportant observations • Don’t make inferences or assumptions when you observe • Qualitative data is obtained through observations that describe color, smell, shape, or some other physical characteristic that is related to the five senses. • Quantitative data is obtained from numerical observations that describe how much, how little, how big or how fast.
Controlled Experiment • A test of a hypothesis • Making observations under controlled conditions • Where only one variable at a time is changed • Systematic approach to test a hypothesis • Parts of An Experiment • Variables: A condition changed in an experiment • Independent • Dependent • Constants: any factor not changed in an experiment • Control: Group/set up that has no changes made to it • Conclusion: A judgment based on the observations made in a controlled experiment
Independent Variable • Changed by the experimenter • Allowed to change • The Cause in Cause and Effect • Manipulated Variable • Happens First • The water’s temperature increased as more heat was applied. • The temperature of the solid caused the density of the solid to change • An increase in phosphorous helped the plants to grow taller.
Dependent Variable • Changes in response to the change in the independent variable • Responding Variable • Happens second • The boiling point increased as salt was added to the water • The hamster grew two inches with an increase in the hormone.
Control • A point of comparison in an experiment • The group that does NOT receive the treatment
Constants • Specifics that remain the same between the control group and the experimental group • Only the independent variable should be changed by the experimenter Examples of Constants:
Conclusion • A conclusionis a judgment based on the information obtained from the experiment
Identify the following • Independent Variable • Dependent Variable • Control • Constants • Possible conclusion • Another hypothesis
Experiment • Kate noticed that she could dissolve more sugar in the tea when it was warm than when it was ice cold. She wondered if this was true for all solids. She decided to design an experiment to see if water temperature effects how much salt can be dissolved. • She chose table salt as her solid to test. She used water as her solvent. • Hypothesis: An increase in the temperature of the water will allow more salt to dissolve, • She placed 100 mL of water in each of 10 250 mL beakers. • She cooled the water in beaker # 1 to 10 degrees C. • The water in beaker #2 was 25 degrees C. • Beaker # 3 water was heated to 35 degrees C. • Beaker # 4 water was heated to 45 degrees C. • Beaker # 5 was heated to 55 degrees C.
Beaker # 6 65 degrees C • Beaker # 7 75 degrees C • Beaker # 8 85 degrees C • Beaker # 9 95 degrees C • Beaker # 10 100 degrees C
She added salt to each beaker while using a magnetic stirrer which provided constant and uniform stirring until no more salt would dissolve. • She measured and recorded the amount of salt that dissolved in each beaker. • Her data is shown below.
Hypothesis and Experiment • Hypothesis: A tentative explanation of observations • A tentative answer • A statement to be tested by an experiment Example: If I give the fish more hormone then they will grow longer. • Experiment: The test of a hypothesis • A controlled set of steps to test a hypothesis
Theory Vs Hypothesis • A theory is a hypothesis that has stood the test of repeated experiments • An explanation of results • Never proven • Can be disproven • All theories are hypotheses . (True) • All hypotheses can become theories. (True) • All hypotheses are theories. (False)
Scientific Law Vs Theory • Observable Fact • True: Always observed • No known exceptions • No explanation • Explanation • Tentative • Can be disproven
Development of a Theory • Start with an observation that evokes a question: Broth spoils when I leave it out for a couple of days. Why? • Using logic and previous knowledge, state a possible answer, called a Hypothesis: Tiny organisms floating in the air must fall into the broth and start reproducing. • Perform an experiment or Test: After boiling some broth, I divide it into two containers, one covered and one not covered. I place them on the table for two days and see if one spoils. Only the uncovered broth spoiled. • Then publish your findings in a peer-reviewed journal. Publication: "Only broth that is exposed to the air after two days tended to spoil. The covered specimen did not." • Other scientists read about your experiment and try to duplicate it. Verification: Every scientist who tries your experiment comes up with the same results. So they try other methods to make sure your experiment was measuring what it was supposed to. Again, they get the same results every time. • In time, and if experiments continue to support your hypothesis, it becomes a Theory: Microorganisms from the air cause broth to spoil. • Useful Prediction: If I leave food items open to the air, they will spoil. If I want to keep them from spoiling, I will keep them covered.
Notes for Demo Penny in Nitric Acid • copper solutions/compounds are blue • colored gases are poisonous • strong acids are corrosive • Copper reacts with nitric acid HNO3 Indicators of a Chemical Change Production of a gas Production of a solid Temperature change Color change
Chemistry is traditionally broken into branches that focus on specific areas such as • Organic chemistry • Inorganic chemistry • Physical chemistry • Analytical chemistry • Biochemistry • Environmental chemistry • Industrial chemistry • Polymer chemistry • Theoretical chemistry • Thermochemistry :
This ClassHS General Chemistry is Inorganic • Inorganic Chemistry: the study of non-carbon based compounds • Organic Chemistry: Study of matter that contains carbon
Technology • Application of Science for human benefit • Good and Bad • Nuclear Technology • Good: Energy Bad: Waste • Computer Technology • Good: Communication Bad: Wasted Time
Pure Science Vs Applied Science • Pure Science: For the sake of the knowledge • Studying butterflies just to know more • Researcher lives on a remote island to daily study the jungle trees • Studying ape behavior • Applied Science: Using science to solve a particular problem • Scientist studying corn in fields to increase the yield for farmers • Scientist searching for a cancer cure
Why is Pure Research Important? • A Base of knowledge when needed • Keeps us current • General not specific and possible commercial • Accidental Discoveries
Mass Vs Weight Mass Weight Affected by gravity W = mg g= 9.8 m/s2 • Not influenced by gravity • Changes only when amount of matter changes • Kilograms or grams
Your Mass Earth Moon Gravity = 1/6th the gravity on Earth Mass = 60 kg Not affected by gravity • M ass = 60 kg
Weight Earth Moon m = 60 kg W = mg g = 9.8m/s2/6 = 1.63 m/s2 W = (60 kg)(1.63m/s2) W = 98 Newtons • m = 60 kg • W = mg • W = (6o kg)(9.8m/s2) • W = 588 Newtons
Environment with No Gravity • Weight only would change • You would weigh less • Amount of Matter is not affected • Mass stays the same
Chance Discoveries • Discoveries made by accident • Not trying to find an answer • Examples • Velcro • Penicillin • Teflon • Chocolate Chip Cookies • The Microwave Oven • Artificial Sweeteners • Curiosity Drives Discovery
Tuesday and Wednesday • Pre-Assessment: Password is • Lab: Dissolving Salt • Electronic Balance • Graduated Cylinder • Post Lab Q’s: Add One: Do you think particle size affects the rate of a chemical reaction? Why? • Lab Equipment Review Using • The Presentation: Lab Equipment from my website • This Electronic Quiz: http://www.sciencegeek.net/Chemistry/taters/labequipment.htm • Vocabulary Review/Practice Using Online Resources • HW) Equipment Test 25, 27, 31, 33-38, 39-45, 48-51