Chapter 1Matter and Measurement

What is Chemistry?

- The study of all substances and the changes that

they can undergo - The CENTRAL SCIENCE

Why Study Chemistry?

- Useful for other sciences
- Required course ?
- Fun and Challenging
- Remember
- Process of Discovery
- Understand Concepts, NOT Single Facts

Scientific Method

Observation

Question

Hypothesis

Experiment

Conclusion

Scientific Method

Conclusion

- Natural Law
- Explains how nature behaves

- Theory
- Explains why nature behaves in a certain way

Prediction

Experiment

Liquids

Liquids

- Definite
- Molecules
- Not affected by

Solids

Solids

- Dont
- Definite
- Molecules
- Not affected by

Gases

- Low
- Density
- Expands to
- Indefinite
- Molecules move

The Metric SystemThe International System of

Units

- Standards of measurement
- Base units (7) Fig 1-14 p. 18
- MASS
- LENGTH
- TIME
- COUNT, QUANTITY
- TEMPERATURE
- ELECTRIC CURRENT
- LUMINOUS INTENSITY

The Metric System

- Derived Units
- AREA
- VOLUME
- ENERGY
- FORCE
- PRESSURE
- POWER
- VOLTAGE
- FREQUENCY
- ELECTRIC CHARGE

The Metric System

- Metric Prefixes make base unit larger or

smaller - Based on 10
- Math method vs. Stairs

Conversion Practice

- Convert a volume of 12 microliters into

centiliters - Express a distance of 15 meters in kilometers
- Convert 83 cm into meters
- Which is the longer amount of time, 1351 ps or

1.2 ns? - Convert 16 dL into L

Types of Measurements

- Mass amount of
- Expressed in
- Does not
- Weight
- Expressed in
- Changes with

Types of Measurements

- Volume the amount of
- Many instruments to measure
- Temperature
- Degrees
- Degress

Density

- Common ratio used in chemistry
- Physical property of a substance
- SI units

- Solid
- Liquid
- Gas

Can change due to temperature and/or pressure

changes

Density

- Find the density of a piece of metal with a

volume of 2.7 cm3 and a mass of 10.8 g.

2. Determine the mass of an object with a density

of 0.24 g/cm3 and a volume of 2 cm3.

Uncertainty in Measurement

- Why are digits in measurements uncertain?
- Instruments never completely free of flaws
- Always involves estimation
- Choose the right instrument for the job
- May be estimated for you (electronic scales)
- Scale is marked but you estimate the in-between

Uncertainty in Measurement

- Precision
- Accuracy

Significant Digits

- All digits known with certainty plus one final

digit which is uncertain (or estimated) - All non-zeros are
- A zero is significant when
- It is
- It is
- A zero is not significant when
- It is
- It is

Significant Digits - PRACTICE

- How many significant digits?
- 54.23
- 23.00005
- 0.0004
- 35000
- 0.000504
- 45.623200
- 5,000,000
- 4,000,000.1

Significant Digits - Calculations

- Addition and Subtraction
- 1.21 5.002 10. 16.212 becomes 16
- 34.5 12.45 23.0505
- 186.31 11.1
- 12.0231 3.86
- 0.100012 120.
- 1200 12 15 0.5

Significant Digits - Calculations

- Multiplication and Division
- The answer has as many sig figs as the number

with the fewest sig figs - 14.8 x 3.1 45.88 becomes 46
- 18.2 x 3.0
- 52/1.5
- 321.868783 x 1
- 2400 x 2.123
- 15000/12.354

Scientific Notation

- Convenient way of writing very large or very

small numbers and showing only significant

figures - Number between 1 10 with a power of ten
- 5120 becomes 5.12 x 103
- Move decimal point in original number to make

number 1-10 - Move left move right -

Scientific Notation Practice

- 123,000
- 0.000045
- 23.45
- 0.0000000003
- 1,000,000

Scientific Notation

- Adding and subtracting
- Multiply and divide

3.38 x 103

Conversion Factors

- Enable movement between metric system and

English system - See back cover of book and Appendix III
- Common conversions you should memorize
- 1 inch 2.54 cm
- 1 mile 1.609 km
- 1 kg 2.20 pounds
- 1 mL 1 cm3
- 0 K -273.15 0C
- 0F 1.8(0C) 32

Dimensional Analysis(Problem Solving)

- Remember ALWAYS use UNITS OF MEASUREMENT in

your work!!! - A technique of converting between units
- Same system (metrics)
- Different systems (inches to meters)
- Chemical equations.later chapters

Dimensional Analysis(Problem Solving)

- Conversion Factors ratio derived from the

equality between 2 different units - CF can be written either way

Dimensional Analysis(Problem Solving)

- The t method

Conversion Factor

Example How many liters are in 125.6 gallons?

Dimensional Analysis(Problem Solving)

Dimensional Analysis(Problem Solving)

How many seconds are in 4.15 hours?

If a student needs 1.5 mL of water, how many cups

does he need?