1 / 42

Chemistry UNIT 1

Chemistry UNIT 1. Susie Smith August, 2010. Chemistry is the study of matter. Scientific Method. A logical method of problem solving. Steps of the Scientific Method. Making observations that lead to a question. Forming a hypothesis to answer the question.

belita
Download Presentation

Chemistry UNIT 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chemistry UNIT 1

  2. Susie SmithAugust, 2010 Chemistry is the study of matter.

  3. Scientific Method • A logical method of problem solving.

  4. Steps of the Scientific Method • Making observations that lead to a question. • Forming a hypothesis to answer the question. • Testing the hypothesis by experimentation. • Making a conclusion based on the results.

  5. Definitions • Observation- use of senses and devices in the lab to obtain information. • Conclusion- a statement based on observations and prior knowledge.

  6. Types of observations • Quantitative- includes numbers and units. • Qualitative- does not include numbers and units. • Examples-

  7. Hypothesis- an educated guess • Explains an observation. • Can be tested. • Will predict an outcome. • Must be written as a statement.

  8. Experiment • Designed to test an hypothesis. • Involves variables • Is performed under controlled conditions.

  9. Variables • Variables are factors that can be changed. • Control variable is a variable that is held constant. • Manipulated or independent variable is changed by the scientist. • Responding or dependent variable changes as a result of the experiment.

  10. International System (SI) • Measuring system used in science (also called the MKS)

  11. Length • Distance between two points • Base Unit- Meter (m) • Instrument- meter stick or metric ruler

  12. Mass • Amount of matter in a substance • Base Unit- gram • SI Unit – kilogram • Instrument- triple-beam balance

  13. Volume • Amount of space an object occupies • Base Unit- liter (L) • Instrument- metric ruler or graduated cylinder

  14. Time • Interval between two occurances • Base Unit- second (s) • Instrument- stop watch

  15. Temperature • Average kinetic energy • Base Unit- Celsius (oC) or Kelvin (K) • Instrument- thermometer.

  16. Scientific Notation • Numbers are expressed in this form: • M X 10n • M is a number between 1 and less than 10. • And n is equal to an exponent.

  17. How to take numbers out of scientific notation • 1 X 103 = 1000 • Positive exponents move the decimal place to the right n spaces. • 1 X 10-3 = .001 • Negative exponents move the decimal place to the left n spaces.

  18. Scientific Notation • 6.2 X 104 • 1.5 X 10-2 • 2.4 X 10-5 • 7.06 X 106 • 6.0 X 106

  19. How to put numbers into Scientific Notation • 6,011,000 • 0.058 • 24 • 0.009009 • 6.734114

  20. Conversion Factors • One large unit = how many smaller units. • One dozen = 12 units.

  21. Common Conversions • “

  22. Conversions • Start every problem with the original amount. • Then use a conversion fact to convert the units of measurement to what you need. • Set up every problem as a fraction with the unit you are looking for on top and the unit you started with on bottom.

  23. Practice Problems • 1 kg = ________ g • 1s = _________ ds • ________ = 1 L • ______ dollars = 100 centidollars • 100 dg = _____ g

  24. How to work your calculator? • Look for EE, X10, or ^ keys on your calculator • Every calculator is different. • Make notes about how to use your calculator.

  25. Practice • Convert 152 cm to m. • Use the conversion fact 1m = 100cm • 152 cm X 1m = 1.52 m 100 cm

  26. Conversion Practice • Convert 62 kg to _________ g. • Convert 1700 mm to _______ m • Convert 0.0056 mm to ______km.

  27. Conversions with Derived Units • Convert 570 g/L= __________ g/mL • 16 m/min = ______________ m/s • Convert 65 km/h =____________ m/s

  28. Order of operations • Please Excuse My Dear Aunt Sally. • Parenthesis • Exponents • Multiply or Divide • Addition or Subtraction

  29. Definitions • Accuracy- closeness of a measurement to the accepted value • Precision- the reproducibility of a measurement

  30. Significant Digits • All measured digits plus 1 estimated digit • Read the smallest division on the instrument and then estimate one more digit • 3.21 cm, _____ significant digits, ____ measured and ___ is estimated.

  31. Zeros and significant digits • Zeros are placeholders. • They are only significant if they are in between two non zero numbers. 906 • They are significant if they follow a non zero number and are after a decimal. 15.00 • They are not significant if they are before a decimal and before a non zero number. 0.0015 • They are significant if a bar is placed on top of the 0.

  32. Rules for rounding • After multiplying or dividing • Round to the least number of significant digits • Round to the weakest link. • Ex. 420 X 100 = _________

  33. Rounding • After adding and subtracting, • Round answer to 1st column containing an estimated digit • Round to the weakest column 12.001 4.02 + 3 19.021 19

  34. Rule of 5’s • When a number is exactly half way between two numbers, always round to the even number. • 12.5 rounds to 12 • 11.5 rounds to 12 • 12.5001 rounds to 13

  35. Scientific Method • Variable- a physical quantity which can change in the experiment • In a good experiment, only one variable is allowed to change.

  36. Parts of an Experiment • Manipulated (independent) variable- is changed by the experimentor • Responding (dependent) variable- depends on the results of the experiment • Control variables- are variables that are held constant on each group.

  37. Weight verses Mass • On the moon, your mass would not change, and your weight would change. • Mass- is the amount of matter an object has • kilograms • Weight- is the affect of gravity pulling on an object • Newtons

  38. Scientific Method • Question • Hypothesis • Research • Experimentation • Conclusion • Retest

  39. Graphing scientific data • X axis- independent variable • Y axis- dependent variable • a means “is directly proportional to”

  40. Straight Line Graph y a x • y = kx , where k is a constant • Slope is y/x or rise/run

  41. Inverse proportion y a 1/x • y = k/x • Graph is a hyperbola

  42. Equations • When the variables of an equation are on the same side of the equal sign, the variables are inversely proportional. • When the variables of an equation are on opposite sides of the equal sign, the variables are directly proportional. • P A = F

More Related