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Transcript of chapter 01 3e
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Roy Kennedy
Massachusetts Bay Community College
Wellesley Hills, MA
Introductory Chemistry, 3rd Edition
Nivaldo Tro
2009, Prentice Hall
Chapter 1
The ChemicalWorld
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What Is Chemistry?
Observation: is sand different than water
Test the similarities and differences between
sand and water.Composition
Types & number of atoms, structure,
Properties
Chemical: how hot, how fast
Physical: size, ability to loose/gain electrons
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Structure Determines Properties
Everything is made of tiny particles called atoms andmolecules.
Chemists study these particles, looking at the kinds,
numbers, structure, size which produce varyingchemical and physical properties.
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The Scientific Method
Humans are by nature curious. Have you ever heard a 3 year old repeatedly ask
why?
Science is just exploring nature. A scientists is just a person exploring. You begin to organize your thoughts into
Observation, you group those observations intoHypotheses, using Experimentation, andformulate Laws or Theories.
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Why Arent the Philosophers
Considered ScientistsPhilosophers:
Observe nature.
Explain the behavior of
nature.
Communicate anddebate ideas with other
philosophers.
Truth is revealedthrough logic and
debate.
Scientists:
Observe nature.
Explain the behavior of
nature.
Communicate anddebate ideas with other
scientists.
Truth is revealedthrough
experimentation.
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Observation Acquiring information or data
Some observations are simpledescriptions
The soda pop is a liquid with a brown
color and a sweet taste. Bubbles are seenfloating up through it.
Some observations compare acharacteristic. A 240-mL serving of soda pop contains
27 g of sugar.
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Hypothesis
Looking at your observations you come upwith:
The sweetness of soda pop is due to the presence ofSugar or
Aluminum
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Experiments
Test your hypotheses with a taste test: sugar andaluminum.
Theory
Sugar is sweet
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Laws
Typically a fact of nature, often a mathconstant/number and unit.Law of Conservation of MassIn a chemical
reaction matter is neither created nor destroyed.
Speed of Light, E = mc2, Daltons Gas Law,
Universal Gas Constant, etc
Unlike California State laws, you cannot
choose to violate a scientific law
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Theories
Explains how nature behaves.Newtons Gravitational Theory: how an apple falls
Daltons Atomic Theory: atoms look like
Darwins Theory of Evolution: we always change
Einstein's Theory of Relativity: light is constant
Used to predict future observations.
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Whats the Difference Between a
Law and a Theory?
Laws: Very specific, What will happen
often expressed in mathematical equations.
Theories:Very general, Why it willhappen, often includes many Laws
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Do we need science?
A history lesson in science A key feature of science are its experiments
Experiments must be duplicated by others!!!
Galileo (1564 - 1642) and Newton (1642 -1727) worked on physics, the first Scientists
Lavoisier is first to use the scientific method on
objects/nature on things that could not be
Seen
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What causes Burning?
Phlogiston TheoryThe mid-1700s theory of how wood or coal burned,
referred to as combustion.
Wood and coal contained a substances calledphlogiston.
When a substance burned it released all or someof its phlogiston into the air .
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Problems with Phlogiston Theory When pure metals burn they should weigh
less (turns into calx)however, metalsalways weigh more when burned, that is the
clax always weighed more than the metal. The reverse experiment: If calx is heated, it
should remove phlogiston from the air beconverted back to the metalhowever theBurning Lens experiment by Lavoisierobserved fixed air being released backinto the air.
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The Great Burning Lens: Trying
to Find Phlogiston - ultimately it
was discredited
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A Better Theory of Combustion
Lavoisier purchased the most accuratescales; scales that would cost over million
of dollars today
Lavoisier carefully preformed hisexperiments weighing them before and after
each combustion experiment.
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A Better Theory of CombustionLavoisier proposed an alternative theory of
combustion based on his experiments:
1. When something burns, it can either remove or
combine with fixed-air.
2. He discovers Oxygen, hydrogen
Lavoisier literally, rewrites all chemistry textbooks.
Lavoisiers idea starts modern chemistry based on
reproducible experimentation---backed with very
accurate measurements.
He is executed by a phlogiston believer-political
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Lord Kelvin, 1850s
"To measure is to know."
"If you can not measure it, you can notimprove it."
Tro's "Introductory Chemistry",Chapter 1
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How to Succeed in Chemistry
Curiosity and yourimagination are your allies
Explore and investigate.
Quantify and calculateEven small differences can
be important!
CommitmentWork regularly and carefully.
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The Best Approach to
Learning Chemistry Learn the vocabulary of chemistry.Definitions and terms.
How common vocabulary is applied to chemistry.
Memorize important information.
Names, formulas, and charges of polyatomic ions.
Solubility rules.
Learn and practice processes.Systematic names and formulas.
Dimensional analysis.
Do the questions and exercises in the chapter to testyour understanding and help you learn the patterns?