Unit 1
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Scientific Method
 Observation
 Questions
 Hypothesis
 Data
 Conclustion
 Results

Hypothesis
A tentative explanation based on observations

Experiment
An observation of natural phenomena carried out in a controlled manner so that the results can be duplicated

Law
States a measurable relationship

Theory
Tested explanation of basic natural phenomena

Mass
the quantity of matter in a material


Law of Conservation of Mass
Matter can neither be created nor destroyed during a normal chemical reaction.

What is the difference between mass and weight?
Weight depends on gravity

Solids
Have a fixed shape and fixed volume

Liquids
Have a fixed volue but not a fixed shape

Gases
Do not have a fixed volume or shape

Physical change
A change in which the chemical composition of the sample does not change

Chemical change
A change in which the chemical composition of the sample changes. (new matter)

Physical properties
characteristics of a material that can be observed without changing the substance (its chemical identity)

Chemical Properties
characteristic of a material which is evident when the material undergoes a chemical change.

Elements
a pure substance that cannot be broken down any further by chemical means.
oxygen, mercury, sulfur

Compounds
A combination of more than one element that can be broken down further by chemical reations.

Heterogeneous mixtures
a mixture in which the properties vary within a sample

Homogeneous mixture
a mixture in which the properties are constant throughout the sample.

Precision
How close the measurements are to one another

Accuracy
Closeness of a measurement ot its true value

Uncertainty
measurements cannot be exact

Significant figues
digits in a mesurement that include all certain digits plus a finial digit with some uncertainty.

Rules to significant digits
 nonzero significant
 confined zeros significant
 leading zeros not significant
 trailing zeros significant with decimal

Rounding
 if next digit is >5 round up
 if next digit is <5 round down
 if next digit is =5 round to nearest even number

Adding and Subtracting Sig Figs
 Last common place that each number has
 Round answer to place of least sig fig

Multiplying and Dividing with Sig Figs
Look at the number of sig fig in all values; report the fewest number of sig fig in answer

Scientific Notation
exponential notation where there is exactly one nonzero digit the the left of the decimal
positive < decimal > negative

Base units of metric system
 length > meter > m
 mass > gram > g
 volume > liter > L
 time > second > s

Measurement staircase and rules
 tera, giga, mega, kilo base
 deci, centi, milli, micro, nano, pico
up stair divide by 10, down stair multiply by 10

Celsius/Fahrenheit Conversion
T_{f} = (9/5) T_{c} + 32.000 F

Celsius/Kelvin Conversion
T_{k} = T_{c} + 273.15

Volume
Length * Width * Height


Common conversions with liters
 1 L = 1 m^{3}
 1 mL = 1 cm^{3}