1 1-1 © 2006 thomson learning, inc. all rights reserved scientific method fact fact: a statement...

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1-1© 2006 Thomson Learning, Inc.All rights reserved

Scientific MethodScientific Method• FactFact: A statement based in direct experience• HypothesisHypothesis: A statement that is proposed,

without actual proof, to explain a set of facts or their relationship.

• TheoryTheory: The formulation of an apparent relationship among certain observed phenomena, which has been verified to some extent.

• --In a sense, a theory is the same as a hypothesis except that, we have a stronger belief in it because more evidence supports it.

• --If, however, we find new evidence that conflicts with it, the theory must be altered or rejected.

Scientific Method

Yes

No

Know the steps of the scientific method.

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Exponential NotationExponential Notation• Used to represent very large or very small

numbers as powers of 10• Examples:

0.00002 is written as 2 x 10-5

2,000,000 is written as 2 x 106

Know how to convert numbers to scientific notation and scientific notation to numbers.

Measurements

Significant Figures

• Measurements – always require significant figures because it is necessary to estimate the last digit when measuring.

For example:– 5 lbs bananas– 36.5 mile trip– 52.50 g

LengthMarks can be read with certainty, and estimate the last digit between marks.

4.2 has 2 significant figures

4.25 has 3 significant figures

Counting Significant Figures

Significant • All non-zero digits

(1 thru 9)• Zero between non-

zero digits (407)• Ending zero of

decimal (3.540)

Not Significant

• Leading zero (0.0047)• Place Holding Zero

(4500)

Significant Figures

• Exact Numbers such as counting objects (5 books; 12 roses) or definitions (12”=1ft) do not require significant figures

Rounding Rules

• If the number to be dropped < 5 then it and all numbers that follow are dropped

• If the number to be dropped > or = 5 then it and all numbers that follow are dropped and the preceding number is increased by one.

Examples are on the next two slides.

Rules for Adding/Subtracting Measurements

• The answer should have the same # of decimal places as the number with the fewest decimal places.

For example:– 61.4532 + 13.7 + 22 + 0.003 = 97.1562

Apply the rule and the correct answer is 97– 14.26 - 1.05041 = 13.20959

Apply the rule and the correct answer is 13.21

Rules for Multiplying/Dividing Measurements

• The answer should have the same # of significant figures as the number with the fewest significant figures.

For example:– 3.6 * 4.27 = 15.372

Apply the rule and the correct answer is 15– 42.1 / 3.695 = 11.393775372124492557510148849797

Apply the rule and the correct answer is 11.4

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Metric SystemMetric System• Table 1.1 Base units in the metric system

LengthVolumeMassTimeTemperatureEnergyAmount of matter

meter (m)liter (L)gram (g)second (s)Celsius (°C)calorie (cal)mole (mol)

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Metric SystemMetric System• Table 1.2 The Most Common Metric Prefixes

giga

mega

kilo

deci

centi

milli

micro

nano

109

106

103

10-1

10-2

10-3

10-6

10-9

G

k

d

c

m

n

Prefix ValueSymbol

M

MnemonicGreat Many kids have dropped over dead converting metrics

until now, Aye.

Use the Mnemonic to remember the first letter of the metric prefixes. The double vertical lines represent decimal places without prefixes.

Mnemonic

Giga kilo deka deci milli nano Mega hecto unit centi micro Angstrom

Remember the names of the prefixes. Unit is an open box for any base measurement: meters, grams, liters, calories, moles, bytes, seconds, bels, Curies….. etc.

Mnemonic

Remember the exponents for each prefix. Note the double vertical lines represent decimal places without prefixes.

109 106 103 102 101 100 10-1 10-2 10-3 10-6 10-9 10-10

MnemonicConvert 750 kbytes to __________ Mbytes

Use the Mnemonic to count the number of decimal places to move the decimal and determine which direction.

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Metric & English SystemsMetric & English Systems• Table 1.3 Some Conversion Factors

Length

1 in. = 2.54 cm1 m = 39.37in.

1 mile = 1.609 km

Mass1 oz1 lb1 kg

===

28.35 g453.6 g2.205 lb

Volume

1 qt1 gal

1 L

===

0.946 L3.785 L33.81 fl oz

1 L = 1.057 qt1 fl oz = 29.57 mL1 g = 15.43 grains

For labs use the conversion definitions in the Lab Manual, and for the test I will give the conversion definitions.

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Factor-Label MethodFactor-Label Method• Conversion factorConversion factor

• a ratio of two different units, used as a multiplier to change from one system or unit to another.

• for example, 1 lb = 463.6 g• Example:Example: convert 381 grams to pounds

• Example:Example: convert 1.844 gallons to milliliters

381 g x 1 lb453.6 g

= 0.840 lb

1.844 gal x 3.785 L1 gal

x 1000 mL1 L

= 6980 mL

TemperatureKnow the freezing point and melting point comparison of the three scales.

Mass vs. Weight

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Mass and WeightMass and Weight• Mass:Mass: the quantity of matter in an object

• mass is independent of location

• Weight:Weight: the result of mass acted upon by gravity• weight depends on location; depends on the force of

gravity at the particular location

Physical States

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The Three States of MatterThe Three States of Matter• GasGas

• has no definite shape or volume.• expands to fill whatever container it is put into.• is highly compressible.

• LiquidLiquid• has no definite shape but a definite volume.• is only slightly compressible.

• SolidSolid• has a definite shape and volume.• is essentially incompressible.

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DensityDensity• Density:Density: the ratio of mass to volume.

• most commonly used units are g/mL for liquids and solids, and g/L for gases.

• Example:Example: If 73.2 mL of a liquid has a mass of 61.5 g, what is its density in g/mL?

d = md = densitym = massV = volumeV

d =mV

= 61.5 g73.2 mL

= 0.840 g/mL

Know the formula.

Note the rule of significant figures controlled the answer.

1 1-1 © 2006 thomson learning, inc. all rights reserved scientific method fact fact: a statement...

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