Monday, Sept. 30 th : “A” Day Tuesday, Oct. 1 st : “B” Day Agenda  Lab questions/problems - collect  Section 2.2: “Studying Matter & Energy” scientific method, hypothesis, variable, control, theory, law, law of conservation of mass  Scientific Method activity  Serendipitous Discoveries Assignment/library work time  Homework: Sec 2.2 review, pg. 53: #1-7 Concept Review: “Studying Matter and Energy”

Lab: “Physical and Chemical Change”  Questions/Problems?  Make sure your conclusion questions are answered fully in complete sentences…  Remember to write your reflection statement!

The Scientific Method  Scientific Method: a series of steps followed to solve problems, including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions.  The scientific method is NOT a series of exact steps, but rather a strategy for drawing sound conclusions.

Experiments are Part of the Scientific Method  An experiment is the process by which scientific ideas are tested.  Scientists are often confronted by situations in which their results don’t turn out as expected.  Scientists don’t view these results as failures.  Unexpected results often give scientists as much information as expected results do.  Unexpected results are as important as expected results.

Scientific Method Activity  Get in groups of 4.  Without opening the bags, use the scientific method to see if you can correctly identify the contents of each bag.  Be quiet so the other groups don’t hear you and record your answers on a piece of paper.  How many processes that are part of the scientific method did you use?  How many items did you identify correctly?

Scientific Discoveries Can Come From Unexpected Observations  Some important discoveries and developments have been made simply by accident. Teflon was discovered by chance.

Scientific Discoveries Can Come From Unexpected Observations  Teflon is used as a thermal insulation device in clothing, as a component in wall coverings, and as a protective coating on metals, glass, and plastics.  Teflon’s properties of very low chemical reactivity and very low friction make it valuable in the construction of artificial joints for human limbs.  Teflon is also used as a roofing material.

Scientific Explanations  Hypothesis: a theory or explanation that is based on observations and that can be tested.  Hypotheses are tested by carrying out experiments.

Scientists Must Identify the Possible Variables  Variable: a factor that could affect the results of an experiment.  A scientist changes variables one at a time to see which variable affects the outcome of an experiment.  To know if your hypothesis is right, the experiment must be designed so that each variable is tested separately.

Each Variable Must be Tested Individually  When a variable is kept constant from one experiment to the next, the variable is called a control and the procedure is called a controlled experiment.

Data From Experiments Can Lead to a Theory  Theory: an explanation for some phenomenon that is based on observation, experimentation, and reasoning.  Any hypothesis that withstands repeated testing may become part of a theory.  Because theories are explanations, not facts, they can be disproved but can never be completely proven.

Theories and Laws Have Different Purposes  Law: a summary of many experimental results and observations; a law tells how things work.  While a theory is an attempt to explain the cause of certain events in the natural world, a scientific law describes the events.  A law is a statement or a mathematical expression that reliably describes the behavior of the natural world.

Theories and Laws Have Different Purposes  Law of conservation of mass: the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes.  Products of a chemical reaction have the same mass as the reactants have.

Models Can Illustrate the Microscopic World of Chemistry  Model: a representation of an object, a system, a process, or an idea.  A model is simpler than the actual thing that is modeled.  Models can be most useful in understanding what is happening at the microscopic level.

Serendipitous Discoveries Assignment  Your assignment is to research and write a 1 page paper about a serendipitous discovery.  The paper can be hand-written or typed, but must be at least 1 full page in length.  You must use at least 2 sources and those sources must be listed at the end of the paper.  You will have time today to begin your research. The rest will be completed outside of class.  You will share your finding with the class on the day the paper is due.

Homework  Sec 2.2 Review, pg. 53: #1-7  Work on serendipitous discoveries paper  Concept Review: “Studying Matter and Energy” Due on day of Chapter 2 test (Oct. 17 th /18 th ) Next Time: Section 2.2 quiz