Welcome to

1

Welcome to Regents Chemistry The Physical
Setting, with Mr. Gardner


2
Unit 1 What is Chemistry?

• The study of the composition of matter and the
  changes that matter can undergo.
• Is it a liquid or a solid?
• Considered the central science as it overlaps the
  other sciences.

3
5 Areas of Study

• Organic study of all chemicals containing the
  element carbon
• Inorganic study of all chemicals without carbon
• Biochemistry study of chemical processes that
  occur in living organisms
• Analytical study of the composition of matter
• Physical study of matter when is undergoes a
  change

4
Why is chemistry important to you

• Helps to explain the natural world
• Why gum changes when you drink something hot or
  cold
• Why apples and/or metals will change colors when
  exposed to air
• Prepares you for a career
• Many jobs may have chemistry related topics
• Makes you an informed citizen
• You may help make decisions in your homes and
  community based on what you learn/know

5
Making Observations

• Using your senses to gather info/data
• Quantitative Quantity, amount or number
• Ex. there are 20 students
• Ex. He made 87 of his free throws
• Qualitative Quality or appearance
• Ex. They are very tall
• Ex. She has red hair

6
The Scientific Method PHEOC(R)

• State the Problem or question you are wondering.
• Form a Hypothesis, or educated guess, about your
  problem.
• Set up a controlled Experiment to test your
  hypothesis.
• Record data and analyze results through
  Observations.
• Draw a Conclusion.
• Repeat the investigation.

7
Experiment Design

• Variables Factors that can change such as
  equipment, temperature, light and time
• Manipulated or independent variable the one that
  is deliberately changed. (Always on the X axis
  in a graph)
• Responding or dependent variable observed and
  changes in response to the manipulated or
  independent variable (Y axis)
• It is important to only change one variable at a
  time
• Controls factors that stay the same in an
  experiment.

8
Scientific Theory

• A well tested explanation that unifies a broad
  range of observations.
• Allows scientists to make accurate predictions.
• May become the dominant view among a majority of
  scientists.
• Is not considered an absolute truth (ex.
  evolution).
• May be revised or replaced as more evidence is
  uncovered.

9
Measurement Tools and Procedures

• In order to retest and replicate experiments, a
  common system of measurement is needed The
  Metric System
• Based on multiples of 10
• Numbers in science without units mean NOTHING and
  have no inherent value
• All numbers need meaningful units

10
SI units (System International)

• Volume? Liter
• Mass? gram
• Length? meter
• Temperature? degrees Kelvin (Celsius used also)
• Time? seconds
• Amount? moles
• Electric Current? amperes (amps)
• grams, liters, meters ROOT or BASE WORDS

11
SI Prefixes

• Prefix Abbreviation Factor
• Tera T 10 12
• Giga G 10 9
• Mega M 10 6
• Kilo K 10 3
• Hecto h 10 2
• Deka da 10 1
• Deci d 10 -1
• Centi c 10 -2
• Milli m 10 -3
• Micro u 10 -6
• Nano n 10 -9
• Pico p 10 -12
• Typically used with ROOT/BASE WORDS

12
Uncertainty in Measurement

• When measuring, it is important to be as accurate
  as possible, however, there is always a bit of
  uncertainty involved
• Last digit is always estimated

13
Accuracy vs. Precision

• Accuracy- how close to the accepted value a
  measurement is
• Precision- how reproducible your results are (how
  close they are to one another)

14
Significant Figures (Sig. Figs)

• Measurement consistent with certainty, plus one
  estimated digit
• Rules for determining number of sig. figs
• If a number has no zero, then all numbers are
  significant
• 473 3 sig. figs
• 27946 5 sig. figs
• Zeros appearing between nonzero numbers are
  significant
• 307 3 sig. figs
• 203,045 6 sig figs

15
Significant Figures (continued)

• Zeros in front of non-zero digits are NOT
  significant
• .00008 1 sig. fig
• 0.00347 3 sig. figs
• Zeros at the end of a number (to the right of the
  decimal) are significant
• .0030 2 sig. figs
• 0.002000 4 sig. figs
• Zeros at the end of a number (to the left of the
  decimal may or may not be significant
• 2000. 4 sig. figs as decimal hold the last
  zero
• 2000 1 sig. fig

16
Atlantic-Pacific Rule (Think USA map)

• Must consider previous rules with this trick
• If decimal is Absent, start counting digits from
  the Atlantic Ocean Side of the number
• Ex. 30410 (start on right side at first non zero
  value and count to the left)
• This value has 4 sig. figs
• If decimal is Present, start counting digits from
  the Pacific Ocean Side of the number
• Ex. 0.057010 (start on left side at first non
  zero value and count to the right)
• This value has 5 sig. figs

17
Rounding Sig Figs

• If the digit following the last digit to be kept
  is
• Greater than/equal to 5, increase the digit
• Less than 5, keep the digit the same.
• Ex. Round 47.6 to 2 sig figs ? 48
• Ex. Round 200.12 to 4 sig figs ? 200.1

18
Addition/Subtraction with Sig. Figs

• The answer must have the same number of digits to
  the RIGHT of the decimal point as there are in
  the measurement with the fewest number of digits
  to the RIGHT of the decimal point
• 125.5 kg 25.263 cm
• 52.68 kg 38.1 cm
• 2.1 kg 63.363 cm 63.4 cm
• 180.28 kg 180.3 kg

19
Multiplication/Division with Sig. Figs

• The answer must have no more sig. figs than the
  measurement with the fewest number of sig. figs
• Example
• 3.05 g 0.3599669539 g/ml 0.360
  g/ml
• 8.473 ml
• Exempt counted s, conversion factors,

20
Scientific Notation

• Consists of 3 parts Mantissa, Base, Exponent
• M 10 n
• Ex. 65,000 km 6.5 X 10 4
• M Mantissa where 1 M lt 10
• 10 Base this value is always 10
• n Exponent Must be a whole number

21
Converting from Standard to Scientific Notation

• Move decimal point so that M falls under the
  above rule.
• The exponent is the of places the decimal will
  be moved.
• Negative (-) if you moved decimal right
• Positive () if you moved decimal left
• Ex. 0. 0 0 0 0 4 5 9
• Moved 5 places to the right
• Thus our answer is 4.59 10-5

22
Converting from Scientific Notation to Standard

• Move decimal an equal amount to the exponent
• Move to the left for negative (-) values
• Move to the right for positive () ones
• Ex. 6.03 10-4
• 6. 0 3
• Thus our answer is 0.000603

23
Significant Figures in Scientific Notation

• All digits in Mantissa are significant
• Ex. 1.24 104 has 3 sig. figs
• Special Note 100 1
• Ex. 4.5 100 4.5 (as equation is 4.5 1)

24
Fixing Numbers not in Correct Scientific
Notation

• If you move decimal to the left, add the number
  of spaces moved, to the exponent
• Ex. 12.1 10-10? 1.21 10-9
• If you move decimal to the right, subtract the
  number of spaces moved, from the exponent
• Ex. 0.016 105? 1.6 103

25
Addition/Subtraction using Scientific Notation

• Exponents must be of equal value (10X)
• You may have a number out of the 1 M lt 10 range
  in this case
• Ex.(4.2 X 10 4)(7.9 X 10 3) can be converted
  to
• (4.2 X 10 4) (.79 X 10 4) 4.99 X 10 4

26
Multiplication/Division using Scientific Notation

• Multiply M factors, add exponents
• Ex. (3103) (4105) 12 108 or 1.2109
• Divide M factors, subtract exponents
• Ex. (100108) (4105) 25 103 or 2.5104

27
Dimensional Analysis(Factor Label)

• Conversion from one unit to another during an
  experiment or calculation may be very important.
• Conversion Factors
• A ratio derived from the equality between
  different units, always equal to 1
• Ex. 12 inches 1 foot (not a ratio)
• 12inches
• 1 foot (ratio) also as 12inches1 foot

28
Dimensional Analysis continued

• Factor Label Method
• Used in calculating metric conversions
• Ex. How many inches are in 40 feet?
• Start with given and set up with conversion
  factor
• 40 feet X 12 inches 480 in
• 1 foot
• The units you want to determine should be the
  numerator in the conversion factor. (inches
  in the above example)

29
Calculations with counted values or constants

• Counted Values and constants/conversion factors
  are considered to have an indefinite number of
  sig. figs.
• Are ignored when determining the number of sig.
  figs in an answer.
• Ex. (1.621 L) (1000ml) 1621 mL
• 1L
• Constant 1L 1.0L 1.00L 1.000L etc
• Other values to consider with this rule
• Percentages and whole numbers in balanced
  equations