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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Tro's "Introductory Chemistry",Chapter 1

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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."


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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?

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chapter 01 3e