Introductory ChemistryIntroductory Chemistry, 2, 2ndnd Edition EditionNivaldo TroNivaldo Tro

Chapter 1The Chemical

World

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 22

Why Does Soda Pop Fizz?Why Does Soda Pop Fizz?

Everything around you is Everything around you is composed of chemicalscomposed of chemicalsMain chemical ingredients of Main chemical ingredients of soda pop: water, sugar and soda pop: water, sugar and carbon dioxidecarbon dioxideProperties of soda pop are Properties of soda pop are due to properties of these due to properties of these chemicalschemicals– Sugar = SweetnessSugar = Sweetness– Water = LiquidWater = Liquid– Carbon dioxide = bubblesCarbon dioxide = bubbles

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 33

Structure Determines PropertiesStructure Determines Properties

Everything is made of tiny particles called Everything is made of tiny particles called atomsatoms

Properties of a substance are determined by Properties of a substance are determined by the kinds, numbers and relationships the kinds, numbers and relationships between atoms between atoms

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 44

What is Chemistry?What is Chemistry?

Chemists try to discover the relationships Chemists try to discover the relationships between the particle structure of matter and between the particle structure of matter and the properties of matter.the properties of matter.

ChemistryChemistry is the science that seeks to is the science that seeks to understand what matter does by studying understand what matter does by studying what atoms and molecules do.what atoms and molecules do.

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 55

The The Scientific MethodScientific MethodA process for understanding nature A process for understanding nature by observing nature and the way it by observing nature and the way it behaves, and by conducting behaves, and by conducting experiments to test ideas.experiments to test ideas.

Parts of the Scientific Method:Parts of the Scientific Method:1.1. Observation Observation 2.2. Formulation of Hypotheses, Formulation of Hypotheses, 3.3. Experimentation Experimentation 4.4. Formulation of Laws and TheoriesFormulation of Laws and Theories

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 66

ObservationObservationA way of acquiring information A way of acquiring information about natureabout natureSome observations are simple Some observations are simple descriptions of characteristics or descriptions of characteristics or behavior of matterbehavior of matter– ““The soda pop is a liquid with a brown The soda pop is a liquid with a brown

color and a sweet taste. Bubbles are color and a sweet taste. Bubbles are seen floating up through it.”seen floating up through it.”

Some observations are Some observations are quantitativequantitative– “ “A 240 mL serving of soda pop A 240 mL serving of soda pop

contains 27 g of sugar.”contains 27 g of sugar.”

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 77

HypothesisHypothesis

A tentative interpretation or explanation A tentative interpretation or explanation of your observationsof your observations– ““the sweet taste of soda pop is due to the the sweet taste of soda pop is due to the

presence of sugar”presence of sugar”

A good hypothesis is one that can be A good hypothesis is one that can be tested to be proved wrong!tested to be proved wrong!– FalsifiableFalsifiable– One test may invalidate or support your One test may invalidate or support your

hypothesishypothesis

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 88

ExperimentsExperiments

Tests of hypotheses, laws or theoriesTests of hypotheses, laws or theories

Can you think of a way to test whether the Can you think of a way to test whether the sweet taste of soda pop is due to the presence sweet taste of soda pop is due to the presence of sugar?of sugar?

Results either Validate (confirm) or Invalidate Results either Validate (confirm) or Invalidate (deny) your ideas(deny) your ideas– Invalidate = Discard or ModifyInvalidate = Discard or Modify

Many times experiments invalidate only parts of the Many times experiments invalidate only parts of the hypothesis or theory, in which case the idea is modifiedhypothesis or theory, in which case the idea is modified

– Validate Validate ≠ Proof your idea will always hold≠ Proof your idea will always hold

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 99

LawLaw

A statement summarizing all past A statement summarizing all past observations: observations:

Law of Conservation of Mass Law of Conservation of Mass

– “– “In a chemical reaction matter is neither In a chemical reaction matter is neither created nor destroyed.”created nor destroyed.”

Allows prediction of future observationsAllows prediction of future observations– So you can test the Law with experimentsSo you can test the Law with experiments

Unlike state laws, you cannot choose to Unlike state laws, you cannot choose to violate a scientific law!violate a scientific law!

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 1010

TheoryTheory

Explanation for the characteristics Explanation for the characteristics and behavior of nature supported by and behavior of nature supported by a lot of experimental evidencea lot of experimental evidence

Models of natureModels of nature– Dalton’s Atomic TheoryDalton’s Atomic Theory

Can be used to predict future Can be used to predict future observationsobservations– So they can be tested by So they can be tested by

experimentsexperiments

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 1111

What’s the Difference Between a What’s the Difference Between a Hypothesis and a Theory?Hypothesis and a Theory?

A A hypothesishypothesis is an explanation of a is an explanation of a single or small number of observationssingle or small number of observations

A A theorytheory is an explanation supported is an explanation supported by a large body of experimental by a large body of experimental evidence validated by numerous evidence validated by numerous scientists scientists

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 1212

What’s the Difference Between aWhat’s the Difference Between aLaw and a Theory?Law and a Theory?

LawsLaws answer the question: answer the question: WhatWhat will will happen? A summary statement; does happen? A summary statement; does not explain.not explain.

TheoriesTheories answer the question: answer the question: WhyWhy does something happen? Provide does something happen? Provide explanations.explanations.– Which will allow you to predict what will Which will allow you to predict what will

happen!happen!

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 1313

The Scientific Method Flow ChartThe Scientific Method Flow Chart

1414

How Scientific Method is Followed How Scientific Method is Followed

2. Hypothesis2. Hypothesis

3. Experiment3. Experiment

a) conclusiona) conclusion

b) submission

c) peer reviewc) peer review

d) publicationd) publication

e) other scientists responde) other scientists respond

try to try to disprovedisprove

try totry tofurtherfurthervalidatevalidate

1. Observation1. Observation

4. Scientific theory4. Scientific theory

3. Experiment3. Experiment

a) conclusiona) conclusion

b) submission

c) peer reviewc) peer review

d) publicationd) publication

e) other scientists responde) other scientists respond

1. Observation1. Observation

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 1515

How to Succeed in ChemistryHow to Succeed in Chemistry

Be Curious and use your Be Curious and use your ImaginationImagination– explore and investigateexplore and investigate

Quantify and CalculateQuantify and Calculate– even small differences can even small differences can

be important!be important!

CommitmentCommitment– Work Regularly & CarefullyWork Regularly & Carefully

Tro's Introductory Chemistry, Chapter 1Tro's Introductory Chemistry, Chapter 1 1616

Guide to Learning ChemistryGuide to Learning Chemistry

Learn the vocabulary of chemistryLearn the vocabulary of chemistry– Definitions of termsDefinitions of terms– How common vocabulary is applied to chemistryHow common vocabulary is applied to chemistry

Memorize important informationMemorize important information– Names, formulas and charges of polyatomic ionsNames, formulas and charges of polyatomic ions

Learn and practice processesLearn and practice processes– Systematic names and formulasSystematic names and formulas– Dimensional analysis (conversions)Dimensional analysis (conversions)

Do the questions and exercises in the chapter Do the questions and exercises in the chapter to test your understanding and help you learn to test your understanding and help you learn the patternsthe patterns