1. Chapter 1 Introduction: Matter and Measurement
Chemistry, The Central Science, 12th or LSU edition
Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten
Chapter 1 Introduction: Matter and Measurement
K R

2. Roadmap:
Physical Objects (bodies, things) Matter, RadiationMatter as atoms, moleculesMatter as electrons, protons, neutrons….Matter properties
Chemistry  Science, Chemistry interested in structure and change of matter and its properties
Science  Practical aspects (units, conversions)

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The Chemical View of Things: Matter
Matter is the physical material
of the universe. It occupies space, has specific properties (like mass) that can be observed and measured.
Matter: Some elementary material objects (electrons, protons, neutrons) combine to form elementary substances, atoms of elements, molecules, ions etc.
Modern chemistry works at molecular level.
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4. Chemistry
In this science we study matter and the changes it undergoes.
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What is Chemistry?
What chemists often try to do is to find the relationships between the structure of matter and the properties of matter we observe
Chemistry is the science that seeks to understand what matter is and what it does by studying what atoms and molecules and the subatomic objects do. In practice, chemistry is different than physics.
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The Scientific Method
A process for trying to understand nature by observing nature and the way it behaves, and by conducting experiments to test our ideas.
Key Characteristics of the Scientific Method include Observation, formulation of Hypotheses, Experimentation and formulation of Laws and Theories
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7. Scientific Method
The scientific method is simply a systematic approach to solving problems.
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8. Scientific method- a visual presentation:
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Laws
Summary of observations that combines some past observations into one general statement about those observations
Law of Conservation of Mass – “In a chemical reaction matter is neither created nor destroyed.”
Allows you to predict future observations
So you can test the Law with experiments
Like in any law, improved experiments and new knowledge could indicate violations and/or extensions of previous scientific laws
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10. CHEMISTRY and CHEMICAL IN THE USA
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11. Units of Measurement

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What is a Measurement?
quantitative observation
comparison to an agreed upon standard
every measurement has a number and a unit
Project: measuring global temperatures
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A Measurement
the unit tells you what standard you are comparing your object property (observable) to
the number tells you
what multiple of the standard the object measures
the uncertainty in the measurement (the procedure for the estimate of uncertainty we will see later)
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14. SI Units Système International d’Unités
Uses a different base unit for each quantity

15. Metric System
Prefixes convert the base units into units that are appropriate for the item being measured.

16. Volume
The most commonly used metric units for volume are the liter (L) and the milliliter (mL).
A liter is a cube 1 dm long on each side.
A milliliter is a cube 1 cm long on each side.

17. Uncertainty in Measurements
Different measuring devices have different uses and different degrees of accuracy.

18. Temperature:
A measure of the average kinetic energy of the particles in a sample.

19. Temperature
In scientific measurements, the Celsius and Kelvin scales are most often used.
The Celsius scale is based on the properties of water.
0C is the freezing point of water.
100C is the boiling point of water.

20. Temperature The Kelvin is the SI unit of temperature.
It is based on the properties of gases.
There are no negative Kelvin temperatures.
K = C

21. Temperature
The Fahrenheit scale is not used in scientific measurements.
F = 9/5(C) + 32
C = 5/9(F − 32)

22. Physical property of a substance
Density:
Physical property of a substance d= m V

23. Uncertainty in Measurement

24. Estimating the Last Digit
for instruments marked with a scale, you get the last digit by estimating between the marks
if possible
mentally divide the space into 10 equal spaces, then estimate how many spaces over the indicator is
1.2 grams
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25. Accuracy versus Precision
Accuracy refers to the proximity of a measurement to the true value of a quantity.
Precision refers to the proximity of several measurements to each other.

26. Significant Figures
The term significant figures refers to digits that were measured.
When rounding calculated numbers, we pay attention to significant figures so we do not overstate the accuracy of our answers.

27. Significant Figures: use exponential notation, or
All nonzero digits are significant.
Zeroes between two significant figures are themselves significant.
Zeroes at the beginning of a number are never significant.
Zeroes at the end of a number are significant if a decimal point is written in the number.

28. Significant Figures
When addition or subtraction is performed, answers are rounded to the least significant decimal place.
When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation.

29. Writing Numbers to Reflect Precision
Significant Figures
Writing Numbers to Reflect Precision

30. Reporting Measurements
measurements are written to indicate the uncertainty in the measurement
the system of writing measurements we use is called significant figures
when writing measurements, all the digits written are known with certainty except the last one, which is an estimate
45.872
certain
estimated
45.872
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31. Dimensional Analysis
We use dimensional analysis to convert one quantity to another.
Most commonly dimensional analysis utilizes conversion factors (e.g., 1 in. = 2.54 cm)
1 in.
2.54 cm
2.54 cm
1 in. or
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32. Dimensional Analysis
Use the form of the conversion factor that puts the sought-for unit in the numerator.
Given unit 
 desired unit
desired unit
given unit
Conversion factor
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33. Dimensional Analysis For example, to convert 8.00 m to inches,
convert m to cm
convert cm to in.
100 cm 
1 m 
1 in.
2.54 cm 
315 in.
8.00 m
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