CHAPTER 1CHAPTER 1WHAT IS CHEMISTRY?WHAT IS CHEMISTRY?

WHAT IS CHEMISTRY?WHAT IS CHEMISTRY?

Chemistry is the study of matter and Chemistry is the study of matter and the transformations it undergoes.the transformations it undergoes.

What is matter?What is matter?– Anything that has mass and takes up Anything that has mass and takes up

space.space.

IMPORTANCE OF IMPORTANCE OF CHEMISTRYCHEMISTRY

Chemistry is all around you. Chemistry is all around you. – Air you breatheAir you breathe– Food you digestFood you digest– Clothes you wearClothes you wear– Textbook you readTextbook you read

Chemistry is often said to be the Chemistry is often said to be the central science.central science.

SCIENCE V.S. TECHNOLOGYSCIENCE V.S. TECHNOLOGY

How is science different from technology?How is science different from technology?

Science:Science: – Experimental investigation and exploration of Experimental investigation and exploration of

natural phenomenanatural phenomena– Pursues knowledge for its own sakePursues knowledge for its own sake– Does not cause change in itselfDoes not cause change in itself

TechnologyTechnology– The practical application of scientific The practical application of scientific

knowledgeknowledge– Leads to change (for better or for worse)Leads to change (for better or for worse)

SCIENCE V.S. TECHNOLOGY SCIENCE V.S. TECHNOLOGY (Cont)(Cont)

Examples of science:Examples of science:– What causes the flu?What causes the flu?– How are atoms put together?How are atoms put together?– How is genetic information stored and How is genetic information stored and

transmitted?transmitted?

Examples of technologyExamples of technology– Flu vaccineFlu vaccine– Atomic bombAtomic bomb– Genetic engineeringGenetic engineering

SCIENTIFIC METHODSCIENTIFIC METHOD

Step 1: Make observationsStep 1: Make observations– Example: I am sick with a stomachache.Example: I am sick with a stomachache.

Step 2: Develop a hypothesisStep 2: Develop a hypothesis– Example: I am sick due to the spoiled food I ateExample: I am sick due to the spoiled food I ate

for lunch.for lunch.

Step 3: Test hypothesis through Step 3: Test hypothesis through experimentsexperiments– Example: Ask others who ate the same food for Example: Ask others who ate the same food for

lunch if they got sick.lunch if they got sick.

SCIENTIFIC METHOD (Cont)SCIENTIFIC METHOD (Cont)

Step 4: Develop a lawStep 4: Develop a law– Law:Law: Summarizes the outcome of several Summarizes the outcome of several

experiments that occur repeatedly and experiments that occur repeatedly and consistently.consistently.

– Example: The spoiled food served at lunch Example: The spoiled food served at lunch makes people sick with a stomachache.makes people sick with a stomachache.

Step 5: Develop a theoryStep 5: Develop a theory– Theory:Theory: Explanation for a why a law exists. Explanation for a why a law exists.– Example: It is the bacteria in the spoiled food Example: It is the bacteria in the spoiled food

that makes people ill.that makes people ill.

SCIENTIFIC METHOD (Cont)SCIENTIFIC METHOD (Cont)

TheoriesTheories– Are never completely certain Are never completely certain – May change as more experiments are May change as more experiments are

performed.performed.– A A modelmodel is a physical picture or is a physical picture or

mathematical expression of a theory.mathematical expression of a theory. Example: Model of the atomExample: Model of the atom

The scientific method must be free of The scientific method must be free of bias.bias.

CLASSIFICATION OF MATTERCLASSIFICATION OF MATTER

ELEMENTSELEMENTS

Elemental substances contain only Elemental substances contain only one type of atomone type of atom

Elements are the building blocks of Elements are the building blocks of mattermatter

There are 115 known elements There are 115 known elements today, 90 which occur naturallytoday, 90 which occur naturally

The periodic table displays the The periodic table displays the elementselements

ELEMENTS (Cont)ELEMENTS (Cont)

Each element has a unique symbolEach element has a unique symbol– The first letter is always capitalized, the The first letter is always capitalized, the

second letter is always lower casesecond letter is always lower case Fluorine is F, not fFluorine is F, not f Cobalt is Co, not CO (which is carbon Cobalt is Co, not CO (which is carbon

monoxide)monoxide)

The smallest unit of an element is The smallest unit of an element is the atomthe atom

COMPOUNDSCOMPOUNDS Pure substances containing more than one Pure substances containing more than one

different element.different element.– NaCl (table salt) NaCl (table salt)

Contains sodium (Na) and chlorine (Cl)Contains sodium (Na) and chlorine (Cl) NaCl is the NaCl is the chemical formulachemical formula

– HH22O (water)O (water) Contains 2 atoms of hydrogen (H) and 1 atom of Contains 2 atoms of hydrogen (H) and 1 atom of

oxygen (O)oxygen (O) HH22O is the chemical formulaO is the chemical formula

Elements in compounds are combined in a Elements in compounds are combined in a definite ratiodefinite ratio– HH22O is water but HO is water but H22OO22 is hydrogen peroxide is hydrogen peroxide

COMPOUNDS (cont)COMPOUNDS (cont)

Are HAre H22 and O and O33 considered elements or considered elements or compounds? Why?compounds? Why?

CLASSIFICATION OF MATTERCLASSIFICATION OF MATTER

Classify the following as an element, Classify the following as an element, compound, homogeneous mixture, compound, homogeneous mixture, or heterogeneous mixture.or heterogeneous mixture.

a.a. FogFogb.b. GasolineGasolinec.c. HeliumHelium

d.d. Sulfuric acid (HSulfuric acid (H22SOSO44))e.e. Orange juice from squeezed oranges Orange juice from squeezed oranges

STATES OF MATTERSTATES OF MATTER

SolidSolid LiquidLiquid Gas Gas

Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings

WATER AND ITS STATES OF WATER AND ITS STATES OF MATTERMATTER

CHANGES IN STATECHANGES IN STATE

Melting: Solid to liquidMelting: Solid to liquid Boiling: Liquid to gasBoiling: Liquid to gas Sublimation: Solid to gasSublimation: Solid to gas

– The above three require input of energyThe above three require input of energy

Condensation: Gas to liquidCondensation: Gas to liquid Freezing: Liquid to solidFreezing: Liquid to solid Deposition: Gas to solidDeposition: Gas to solid

– The above three release energyThe above three release energy

PHYSICAL CHANGESPHYSICAL CHANGES

Do not alter the chemical identity of Do not alter the chemical identity of the substancethe substance– Examples include:Examples include:

Any change in the state of matter (e.g. Any change in the state of matter (e.g. freezing or boiling water)freezing or boiling water)

Sawing woodSawing wood Crushing a tabletCrushing a tablet Bending a wireBending a wire Dissolving salt in waterDissolving salt in water

PHYSICAL PROPERTIESPHYSICAL PROPERTIES

Characterize the physical state and Characterize the physical state and physical behavior of a substancephysical behavior of a substance

Each substance has unique physical Each substance has unique physical propertiesproperties

ExamplesExamples– Sulfur appears as a yellow powderSulfur appears as a yellow powder– The boiling point of water is 100 The boiling point of water is 100 ooCC– Carbon monoxide is odorlessCarbon monoxide is odorless

CHEMICAL CHANGESCHEMICAL CHANGES

Changes the identity of the substance Changes the identity of the substance as the chemical composition changes.as the chemical composition changes.– Also called Also called chemical reactionschemical reactions

Examples:Examples:– Tarnishing of silver Tarnishing of silver (Ag forms AgS) (Ag forms AgS) – Rusting of iron Rusting of iron

(Fe forms Fe(Fe forms Fe22OO33))

CHEMICAL REACTIONSCHEMICAL REACTIONS Are expressed using chemical equations.Are expressed using chemical equations.

Rusting of iron:Rusting of iron:4 Fe + 3 O4 Fe + 3 O22 2 Fe 2 Fe22OO3 3 (rust)(rust)

reactants productsreactants products

Meaning: Meaning: Four atoms of iron react with Four atoms of iron react with

three three molecules of oxygen to molecules of oxygen to form two form two molecules of rustmolecules of rust

CHEMICAL REACTIONS CHEMICAL REACTIONS (Cont)(Cont)

Zn + 2 HCl Zn + 2 HCl ZnCl ZnCl22 + H + H22

Zinc hydrochloric acid zinc chloride hydrogen gasZinc hydrochloric acid zinc chloride hydrogen gas

Meaning: Meaning:

One atom of zinc reacts with two One atom of zinc reacts with two molecules of hydrochloric acid to molecules of hydrochloric acid to produce one molecule of zinc chloride produce one molecule of zinc chloride and one molecule of hydrogen gas.and one molecule of hydrogen gas.

CHEMICAL PROPERTIESCHEMICAL PROPERTIES

Describe ways pure substances Describe ways pure substances behave when interacting with other behave when interacting with other pure substances.pure substances.

ExamplesExamples– Iron reacts with oxygen to form rust.Iron reacts with oxygen to form rust.– Platinum does not react with oxygen at Platinum does not react with oxygen at

room temperature.room temperature.

PRACTICE PROBLEMPRACTICE PROBLEM

Identify the following properties andIdentify the following properties andchanges as physical or chemical.changes as physical or chemical.

a.a. The copper sheets that form the “skin” The copper sheets that form the “skin” of the Statue of Liberty have acquired of the Statue of Liberty have acquired a greenish coating over the years.a greenish coating over the years.

b.b. Carbon appears as black powder.Carbon appears as black powder.c.c. Adding food coloring to water.Adding food coloring to water.d.d. Wood burns in air.Wood burns in air.