1. Chemistry the study of matter and energy the study of the composition of substances and the changes they undergo.

3. Scientific Method A logical approach to solving problems 1. Define a problem / ask a question 2. Research the Problem Look things up (internet, books, journals) Do Interviews Make observations using your five senses 3. Form a Hypothesis An educated suggestion/answer to the problem Must be specific and measurable (testable) Typically an if-then statement

4. Scientific Method 4. Experiment Make observations, take measurements, and gather data to test your hypothesis The experiment needs to be reproducible Independent Variable – one “thing” you are changing in your experiment (can only have one) Dependent Variable – one “thing” you are measuring in your experiment – depends on the independent variable (can only have one) Control – everything that is not being changed or being tested

5. Scientific Method 5. Conclusion Explain how your data either supports your hypothesis or does not, provide reasons for failure 6. Share Results. Modify Communicating your results with your peers or fellow scientists helps confirm or deny your hypothesis. Modify your hypothesis and retest if necessary

6. Which color of M&M’s is the most abundant in a typical package of M&M’s Together: Research Hypothesis In groups? Experiment (data table) Analysis (graph) Conclusion (write up)

7. Design an Experiment Choose a question from the list below as a topic for an experiment. As one of the first steps in planning an investigation, you may need to narrow your original question. Then write a hypothesis and design an experiment to answer the question. Be sure to include all the necessary parts of an experiment, such as naming the independent and dependent variables. Include a data table you could use for recording your observations. – How is the heart rate affect by exercise? – Does sand in wheels of my inline skates affect how fast they roll? – Will a wet sheet dry when hung outside on a freezing day? – How is gas mileage affect by the type of gasoline used? – Does cold water freeze fast than hot water?

8. Theory vs. Law Theory – explains WHY something is; can be repeated, but not proven. Scientific Law – description of what is happening, does NOT explain why. Ex: A balloon expands in the hot sun Theory – Increasing the heat of gas particles, increases the speed &the number of collisions. This increases the volume. Scientific Law – the volume of a gas is directly proportional to the temperature if the pressure is kept constant.

10. Theory vs. Law Are based on observations Testable explanations that have not been proven Have evidence to back the claim Repeatedly verified over a long period of time Explains why something is Are based on facts Have been proven Have evidence and results to support the proof Does NOT explain why Description of what is happening Statement of a relationship or a regularity THEORY LAW

11. Measurments Made in everyday life & science measurements include a number & a unit Qualitative vs. Quantitative Measurements Qualitative - a descriptive, non-numerical form. It takes a long time to walk home. Quantitative Measurement –a number with units. It takes 37 minutes & 20 seconds to walk home.

12. Measurement: International System of Units (SI) Open to Table 1 – pg 34 of text Length – metric unit is the meter (m) Mass – the quantity of matter an object contains. Metric unit is Kg (1Kg=1000g) Weight – force – measure of pull on mass by gravity. Changes w/gravity, you weigh 1/6 of your weight on the moon. Volume – the space occupied by matter. unit is Liter (L) Volume of a cube or rectangle: V= l x w x h

13. Common items not in notes A penny is exactly 2.5 g nickel weighs exactly 5 g A doorknob is about 1 m high.

14. Volume and water 1 milliliter is the same volume as 1 cubic centimeter. 1 mL of water has a mass of 1 g 1 L of water has a mass of 1 kg

15. Glassware for measuring liquid volume: Beaker Graduated Erlenmeyer flask cylinder Density- mass ÷ volume (g/ml) or (g/cm ) Density –how tightly the atoms are packed together.

16. Most solids are denser than their liquids. However…water is an exception.

17. Water molecules Water molecules expand in their solid form. This makes them less dense so they float in their liquid!!

18. Metric Prefixes: used to express very large or very small numbers. Kilo – 1000 times larger = x10 3 Hecto – 100 times larger = x10 2 Deca – 10 times larger = x10 1 deci – 10 times smaller = x10 -1 centi – 100 times smaller = x10 -2 milli – 1 000 times smaller = x10 -3 micro – 1 000 000 times smaller = x10 -6 nano – 1 000 000 000 times smaller = x10 -9 COPY WHAT I DO ON THE OVERHEAD!!

19. Dimensional Analysis Conversion Factor – any fraction in which the numerator equals the denominator Ex: 1 foot=12 inches or 1 foot 12 inches Dimensional Analysis – using the conversion factor to change one unit into another unit Example: convert 36 inches into feet 36 inches x 1 foot = 3 feet 1 12 inches

20. Dimensional Analysis (continued) Note: Units that you want to cancel go in the denominator of the conversion factor. Always put the given number and units that you are changing over 1. Multiple Step Problems –more than 1 conversion factor Given (con. factor)(con. factor)(con. factor) = wanted Example: convert 15 days into minutes 15 days x 24 hours x 60 minutes = 21,600 minutes 1 1 day 1 hour

21. Lets practice from our homework: Open book to pg 42