CHAPTER 3LABORATORY CHEMISTRY1 CHAPTER 3 THE STRUCTURE OF MATTER.

CHAPTER 3 LABORATORY CHEMISTRY 1

CHAPTER 3CHAPTER 3THE STRUCTURE OF MATTERTHE STRUCTURE OF MATTER


ATOMIC STRUCTUREATOMIC STRUCTURE

1. EARLY MODELS OF THE ATOM1. EARLY MODELS OF THE ATOM 2. DISCOVERING ATOMIC 2. DISCOVERING ATOMIC

STRUCTURESTRUCTURE 3. MODERN ATOMIC THEORY3. MODERN ATOMIC THEORY 4. CHANGES IN THE NUCLEUS4. CHANGES IN THE NUCLEUS


EARLY MODELS OF THE EARLY MODELS OF THE ATOMATOM

DEMOCRITUS: (450 BC)DEMOCRITUS: (450 BC)– ““ATOMOS”ATOMOS”

THE SMALLEST PARTICLE OF AN ELEMENT THE SMALLEST PARTICLE OF AN ELEMENT THAT RETAINS THE CHEMICAL IDENTITY THAT RETAINS THE CHEMICAL IDENTITY OF THAT ELEMENT.OF THAT ELEMENT.

ARISTOTLE:ARISTOTLE:– EARTH, AIR, FIRE, AND WATEREARTH, AIR, FIRE, AND WATER

DEMOCRITUS



LAVOISIER, ANTON: (LATE 1700’S)LAVOISIER, ANTON: (LATE 1700’S)– LAW OF CONSERVATION OF MATTER LAW OF CONSERVATION OF MATTER

(AND ENERGY)(AND ENERGY) PROUST, JOSEPH: (1799)PROUST, JOSEPH: (1799)

– LAW OF CONSTANT COMPOSITIONLAW OF CONSTANT COMPOSITION DALTON, JOHN (1803)DALTON, JOHN (1803)

– SCHOOL TEACHERSCHOOL TEACHER– ATOMIC THEORY OF MATTERATOMIC THEORY OF MATTER



DALTON’S ATOMIC THEORYDALTON’S ATOMIC THEORY– EACH ELMENT IS COMPOSED OF EXTREMELY EACH ELMENT IS COMPOSED OF EXTREMELY

SMALL PARTICLES CALLED ATOMS.SMALL PARTICLES CALLED ATOMS.– ALL ATOMS OF A GIVEN ELEMENT ARE ALL ATOMS OF A GIVEN ELEMENT ARE

IDENTICAL, BUT THEY DIFFER FROM THOSE IDENTICAL, BUT THEY DIFFER FROM THOSE OF ANY OTHER ELEMENT.OF ANY OTHER ELEMENT.

– ATOMS ARE NEITHER CREATED NOR ATOMS ARE NEITHER CREATED NOR DESTROYED IN ANY CHEMICAL REACTION.DESTROYED IN ANY CHEMICAL REACTION.

– A GIVEN COMPOUND ALWAYS HAS THE SAME A GIVEN COMPOUND ALWAYS HAS THE SAME RELATIVE NUMBERS AND KINDS OF ATOMS.RELATIVE NUMBERS AND KINDS OF ATOMS.



WHY IS THERE SUCH DIVERSITY IN WHY IS THERE SUCH DIVERSITY IN NATURE IF THERE ARE ONLY ABOUT 100 NATURE IF THERE ARE ONLY ABOUT 100 DIFFERENT KINDS OF ATOMS ?DIFFERENT KINDS OF ATOMS ?


DISCOVERING ATOMIC DISCOVERING ATOMIC STRUCTURESTRUCTURE

FARADAY, MICHAEL (1839)FARADAY, MICHAEL (1839)– SUGGESTED THAT THE STRUCTURE SUGGESTED THAT THE STRUCTURE

OF ATOMS WAS RELATED TO OF ATOMS WAS RELATED TO ELECTRICITY.ELECTRICITY.

FRANKLIN, BENJAMIN (MID-1700’S)FRANKLIN, BENJAMIN (MID-1700’S)– STATIC ELECTRICITYSTATIC ELECTRICITY– BATTERIESBATTERIES– ““POSITIVE AND NEGATIVE CHARGES”POSITIVE AND NEGATIVE CHARGES”



CATHODE RAY TUBECATHODE RAY TUBE– INVENTED IN THE MID-1800’SINVENTED IN THE MID-1800’S

-+

ELECTRON BEAMANODE

CATHODE



– THOMSON, J.J. (1896)THOMSON, J.J. (1896) DISCOVERED AND NAMED DISCOVERED AND NAMED

ELECTRONSELECTRONS DETERMINED THE CHARGE (1.76 X DETERMINED THE CHARGE (1.76 X

101088 COULOMBS/GRAM) COULOMBS/GRAM) ““PLUM-PUDDING” MODEL OF THE PLUM-PUDDING” MODEL OF THE

ATOMATOM



– RUTHERFORD, ERNEST RUTHERFORD, ERNEST (EARLY (EARLY 1900’S)1900’S)

ALPHA(2+) AND BETA(1-) RADIATION ALPHA(2+) AND BETA(1-) RADIATION (GAMMA RADIATION WAS DISCOVERED (GAMMA RADIATION WAS DISCOVERED LATER)LATER)

– MADE OF PARTICLESMADE OF PARTICLES


RUTHERFORD’S GOLD FOIL RUTHERFORD’S GOLD FOIL EXPERIMENTEXPERIMENT

GOLDFOIL



THE NUCLEAR ATOMTHE NUCLEAR ATOM– ALPHA SCATTERING EXPERIMENT ALPHA SCATTERING EXPERIMENT

(GOLD FOIL EXPERIMENT)(GOLD FOIL EXPERIMENT)– RUTHERFORD NAMES THE NUCLEUS RUTHERFORD NAMES THE NUCLEUS

AND DETERMINES ITS CHARGEAND DETERMINES ITS CHARGE– THE RUTHERFORD/BOHR MODEL OF THE RUTHERFORD/BOHR MODEL OF

THE ATOMTHE ATOM

Well…I’m Ernie

Rutherford ! And I love a good Cigar!

Hi..I’m Niels Bohr ! And I

love Physics !


MODERN ATOMIC THEORYMODERN ATOMIC THEORY

THE STRUCTURE OF THE ATOMTHE STRUCTURE OF THE ATOM– NUCLEUSNUCLEUS

PROTONS PROTONS NEUTRONSNEUTRONS

– ELECTRONSELECTRONS– RUTHERFORD’S VISUALIZATION RUTHERFORD’S VISUALIZATION

(MINATURE SOLAR SYSTEM)(MINATURE SOLAR SYSTEM)– UNCERTAINTY (ELECTRON CLOUD)UNCERTAINTY (ELECTRON CLOUD)


“PLUMB-PUDDING”

MODEL

“SOLARSYSTEM”MODEL



PARTICLE LOCATION CHARGEMASS

(GRAMS)MASS(AMU)

PROTON INSIDENUCLEUS

+1.602 X 10-19 1.673 X 10-24 1.0073 = 1

NEUTRON INSIDENUCLEUS 0 1.675 X 10-24 1.0087 = 1

ELECTRON OUTSIDENUCLEUS

-1.602 X 10-19 9.109 X 10-28 0.0006 = 0

NOTE THAT EVEN THOUGH THE MASS OF AN ELECTRONIS FAR LESS THAN A PROTON….THE CHARGES ARE OF THE SAME MAGNITUDE BUT OPPOSITE

1.63 X 10-24

9.109 X 10-29



ATOMIC NUMBERSATOMIC NUMBERS– MOSELEY, HENRY (1887-1915)MOSELEY, HENRY (1887-1915)

STUDENT OF RUTHERFORDSTUDENT OF RUTHERFORD DISCOVERED THE PROTON (UNIQUE DISCOVERED THE PROTON (UNIQUE

POSITIVE CHARGE OF THE NUCLEUS)POSITIVE CHARGE OF THE NUCLEUS) ATOMIC NUMBER = NUMBER OF ATOMIC NUMBER = NUMBER OF

PROTONS IN THE NUCLEUS AND ALSO = PROTONS IN THE NUCLEUS AND ALSO = THE NUMBER OF ELECTRONS AROUND THE NUMBER OF ELECTRONS AROUND THE NUCLEUSTHE NUCLEUS



NN14.0067

ATOMIC MASS

ATOMIC NUMBER

Atomic Symbol

NITROGEN

ElementName

PERIODIC TABLEPERIODIC TABLE

7



WRITING THE ELEMENTS TO WRITING THE ELEMENTS TO CALCULATE PROTONS, NEUTRONS, CALCULATE PROTONS, NEUTRONS, AND ELECTRONSAND ELECTRONS– TO CALCULATE THE NUMBER OF TO CALCULATE THE NUMBER OF

NEUTRONS, SUBTRACT THE NUMBER NEUTRONS, SUBTRACT THE NUMBER OF PROTONS FROM THE ATOMIC MASSOF PROTONS FROM THE ATOMIC MASS

– THE NUMBER OF ELECTRONS = THE THE NUMBER OF ELECTRONS = THE NUMBER OF PROTONS (ATOMIC NUMBER OF PROTONS (ATOMIC NUMBER) IN A NEUTRAL ATOMNUMBER) IN A NEUTRAL ATOM



Na1123

ATOMIC MASS“” IN AMU

ATOMIC NUMBER“Z” NUMBER

12NUMBER OFNEUTRONS

THIS IS ALSO THE NUMBER OF ELECTRONS IN A GROUND STATE

ATOM!!!!!



IONSIONS– WHEN AN ATOM GAINS OR LOSES AN WHEN AN ATOM GAINS OR LOSES AN

ELECTRON IT ACQUIRES AN ELECTRICAL ELECTRON IT ACQUIRES AN ELECTRICAL CHARGECHARGE

– PLACE THE APPROPRIATE CHARGE SIGN PLACE THE APPROPRIATE CHARGE SIGN AND NUMBER AT THE UPPER RIGHT OF THE AND NUMBER AT THE UPPER RIGHT OF THE ELEMENT SYMBOLELEMENT SYMBOL

N3+

CHARGE OF AN ION = NUMBER OF PROTONS-NUMBER OF ELECTRONSCHARGE OF AN ION = NUMBER OF PROTONS-NUMBER OF ELECTRONS

O2- Fe2+ Cl2- Ca2+


PRACTICEPRACTICE

N7

14N

7

14 +3

LOSES 3 ELECTRONS

GROUND STATE ATOMNEUTRAL (NO CHARGE)

(+7) + (-7) = 0

THE NUMBER OF PROTONS DO NOT

CHANGEAN ION

A CHARGED ATOM(+7)+( -4) = 3 +

PROTONS

ELECTRONS

CHARGE

PROTONS

CHARGE

ELECTRONS



ISOTOPESISOTOPES– ATOMS THAT HAVE THE SAME ATOMS THAT HAVE THE SAME

NUMBER OF PROTONS BUT NUMBER OF PROTONS BUT DIFFERENT NUMBERS OF DIFFERENT NUMBERS OF NEUTRONS (OVERWEIGHT OR NEUTRONS (OVERWEIGHT OR UNDERWEIGHT ATOMS)UNDERWEIGHT ATOMS)

– NAMED BY THE ISOTOPES MASS NAMED BY THE ISOTOPES MASS NUMBER (PROTONS + NEUTRONS)NUMBER (PROTONS + NEUTRONS)



C126 C14

6GROUND STATE

CARBONRADIOACTIVE

CARBON

CARBON-12 CARBON-14



THE MASS OF AN ATOMTHE MASS OF AN ATOM– ATOMIC MASS UNITS (AMU)ATOMIC MASS UNITS (AMU)– AVERAGE MASS OF AN ELEMENT’S AVERAGE MASS OF AN ELEMENT’S

ATOMS IS CALLED THE ATOMIC MASS.ATOMS IS CALLED THE ATOMIC MASS.


CHANGES IN THE CHANGES IN THE NUCLEUSNUCLEUS

NUCLEAR REACTIONS CHANGE THE NUCLEAR REACTIONS CHANGE THE COMPOSITION OF AN ATOM’S COMPOSITION OF AN ATOM’S NUCLEUS.NUCLEUS.

NUCLEAR STABILITYNUCLEAR STABILITY– STABLE NUCLEUS (NOT RADIOACTIVE)STABLE NUCLEUS (NOT RADIOACTIVE)

RADIOACTIVE DECAYRADIOACTIVE DECAY– RADIATION (ALPHA, BETA, AND RADIATION (ALPHA, BETA, AND

GAMMA)GAMMA)



TYPES OF RADIATIONTYPES OF RADIATIONNAME IDENTITY CHARGE

PENETRATINGABILITY

Alpha ()Helium-4

nuclei2+

Low, stoppedby paper

Beta () electrons 1-Medium,

stopped byheavy clothing

Gamma ()High energynon-particle

radiationnone

High, stoppedby lead


ALPHA-BETA-GAMMA ALPHA-BETA-GAMMA SCATTERINGSCATTERING



Alpha decayAlpha decay

4222286

22688 RnRa



Hello, my name is Lise Meitner. I was born in Austria, and fled to Denmark when the Nazis

took power in the early 1930’s. I was the physicist who

interpreted the work of Otto Hahn and Fritz Straussman in

1932. I worked with my nephew, Otto Frisch, and concluded that

neutrons actually cleaved thenucleus of an atom of uranium into two or more fragments. This was never suspected. I also coined the phrase

“NUCLEAR FISSION”. After World War II I moved

to the U.S.


Beta decayBeta decay


0113154

13153 XeI



Gamma decayGamma decay

0023592

23592 UU



WHAT CHANGES ACCOMPANY A WHAT CHANGES ACCOMPANY A NUCLEAR REACTION?NUCLEAR REACTION?

DEFINE RADIOACTIVITY.DEFINE RADIOACTIVITY. IS ALL RADIOACTIVITY COMPOSED IS ALL RADIOACTIVITY COMPOSED

OF PARTICLES ?OF PARTICLES ? DESCRIBE THE FORCE THAT DESCRIBE THE FORCE THAT

HOLDS THE NUCLEUS TOGETHER.HOLDS THE NUCLEUS TOGETHER.

CHAPTER 3LABORATORY CHEMISTRY1 CHAPTER 3 THE STRUCTURE OF MATTER.

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