the structure of the atom - parkway · pdf file1 the structure of the atom atomic models...

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THE STRUCTURE OF THE ATOM

THE STRUCTURE OF THE ATOM

ATOMIC MODELSATOMIC MODELS

PIONEERS OF THE ATOMPIONEERS OF THE ATOM

•DEMOCRITUS

•LAVOISIER

•DALTON

•THOMPSON

•RUTHERFORD

•BOHR

•DEMOCRITUS

•LAVOISIER

•DALTON

•THOMPSON

•RUTHERFORD

•BOHR

THE EARLY ATOMTHE EARLY ATOM

•DEMOCRITUS

IS THE MAN!!!

•YOU KNOW IT!

•DEMOCRITUS

IS THE MAN!!!

•YOU KNOW IT!

IT’S ALL

GREEK

TO ME...

2

DEMOCRITUSDEMOCRITUS• HE PROPOSED THAT ALL THE MATTER IN THE UNIVERSE IS COMPOSED OF TINY PARTICLES

• THESE PARTICLES ARE INDIVISABLE

• HE CALLED THESE PARTICLES ATOMOS (MEANS INDIVISABLE)

• BUT HE HAD AN OPPONENT…

• HE PROPOSED THAT ALL THE MATTER IN THE UNIVERSE IS COMPOSED OF TINY PARTICLES

• THESE PARTICLES ARE INDIVISABLE

• HE CALLED THESE PARTICLES ATOMOS (MEANS INDIVISABLE)

• BUT HE HAD AN OPPONENT…

ARISTOTLE = SCEPTICARISTOTLE = SCEPTIC

DEMOCRITUS IS

AN

IGNORAMUS!

ARISTOTLE WAS

MUCH MORE

POPULAR AND HE

OPPOSED THE IDEA

OF ATOMS!

ARISTOTLE WAS

MUCH MORE

POPULAR AND HE

OPPOSED THE IDEA

OF ATOMS!

ARISTOTLE = SCEPTICARISTOTLE = SCEPTIC

DEMOCRITUS IS

AN

IGNORAMUS!

ARISTOTLE

BELIEVED THAT

MATTER WAS

CONTINUOUS.

ARISTOTLE

BELIEVED THAT

MATTER WAS

CONTINUOUS.

3

DEMOCRITUS’

ATOMS

DEMOCRITUS’

ATOMS

SO...CHEMISTRY DIED

FOR ABOUT 1400 YEARS

SO...CHEMISTRY DIED


UNTIL...UNTIL...

SO...CHEMISTRY DIED


SO...CHEMISTRY DIED


IN THE

1700’S

IN THE

1700’S

4

FOUNDATIONS OF ATOMIC THEORYFOUNDATIONS OF ATOMIC THEORY

• THE PREDOMINATE BELIEF BY THE MID 1700’S WAS THE MODERN DEFINITION OF AN ELEMENT AS A SUBSTANCE THAT CANNOT BE BROKEN DOWN BY ORDINARY CHEMICAL MEANS

• THE PREDOMINATE BELIEF BY THE MID 1700’S WAS THE MODERN DEFINITION OF AN ELEMENT AS A SUBSTANCE THAT CANNOT BE BROKEN DOWN BY ORDINARY CHEMICAL MEANS


• IT WAS ALSO BELIEVED THAT ELEMENTS COMBINE TO FORM COMPOUNDS THAT HAVE DIFFERENT PHYS AND CHEM PROPERTIES THAN THOSE OF THE ELEMENTS THAT FORM THEM.

• IT WAS ALSO BELIEVED THAT ELEMENTS COMBINE TO FORM COMPOUNDS THAT HAVE DIFFERENT PHYS AND CHEM PROPERTIES THAN THOSE OF THE ELEMENTS THAT FORM THEM.


• HOWEVER, THERE WAS CONTROVERSY AS TO WHETHER ELEMENTS ALWAYS COMBINE IN THE SAME RATIO WHEN FORMING A PARTICULAR COMPOUND.

• HOWEVER, THERE WAS CONTROVERSY AS TO WHETHER ELEMENTS ALWAYS COMBINE IN THE SAME RATIO WHEN FORMING A PARTICULAR COMPOUND.

5


• IN THE 1790’S, THE STUDY OF MATTER WAS REVOLUTIONIZED BY A NEW EMPHASIS ON THE QUANTITATIVE ANALYSIS

–SCIENTISTS’ INVESTIGATIONS WERE MADE MORE ACCURATE BY NEW IMPROVED BALANCES

• IN THE 1790’S, THE STUDY OF MATTER WAS REVOLUTIONIZED BY A NEW EMPHASIS ON THE QUANTITATIVE ANALYSIS

–SCIENTISTS’ INVESTIGATIONS WERE MADE MORE ACCURATE BY NEW IMPROVED BALANCES

MATTER CAN BE

NEITHER CREATED

NOR DESTROYED.

ANTOINNE LAVOISIER TOOK ADVANTAGE… ANTOINNE LAVOISIER TOOK ADVANTAGE…

HE BEGAN TO GATHER

EVIDENCE ABOUT HOW

MATTER BEHAVED

BEFORE AND AFTER A

REACTION.

HE BEGAN TO GATHER

EVIDENCE ABOUT HOW

MATTER BEHAVED

BEFORE AND AFTER A

REACTION.

MATTER CAN BE

NEITHER CREATED

NOR DESTROYED.

ANTOINNE LAVOISIER TOOK ADVANTAGE… ANTOINNE LAVOISIER TOOK ADVANTAGE…

HE DISCOVERED THAT THE TOTAL MASS OF THE INGREDIENTS OF A

CHEMICAL REACTION WAS THE SAME AS THE TOTAL MASS OF THE RESULTS

HE DISCOVERED THAT THE TOTAL MASS OF THE INGREDIENTS OF A

CHEMICAL REACTION WAS THE SAME AS THE TOTAL MASS OF THE RESULTS

6

THE LAW OF

DEFINITE

PROPORTION

THE LAW OF

MULTIPLE

PROPORTIONS

I’M BETTER

LOOKING THAN

PROUST!

7

LAW OF

DEFINITE

PROPOR-

TIONS

A CHEM COMPD IS ALWAYS COMPOSED OF THE SAME ELEM. IN THE SAME PROPOR. BY MASS

LAW OF

MULTIPLE

PROPOR-

TIONS

IF 2 DIFFERENT COMPDS ARE COMPOSED OF THE SAME 2

ELEMTS, THEN THE RATIO OF OF THE ELEMNTS IS ALWAYS A RATIO OF SMALL WHOLE #’S

++ ==

C O CO

CARBON MONOXIDECARBON

MONOXIDE

++ ==

C O CO

CARBON MONOXIDECARBON

MONOXIDE

++ ==

C O CO2

CARBON DIOXIDECARBON DIOXIDE

++

O

DALTON’S THOUGHTSDALTON’S THOUGHTS• IN 1808, JOHN DALTON PROPOSED AN EXPLANATION FOR THE LAW OF CONS OF MASS, THE LAW OF DEFINITE PROPORTIONS, & FORMULATED THE LAW OF MULTIPLE PROPORTIONS.

• IN 1808, JOHN DALTON PROPOSED AN EXPLANATION FOR THE LAW OF CONS OF MASS, THE LAW OF DEFINITE PROPORTIONS, & FORMULATED THE LAW OF MULTIPLE PROPORTIONS.

DALTON’S THOUGHTSDALTON’S THOUGHTS• HE REASONED THAT ELEMENTS WERE COMPOSED OF ATOMS & THAT ONLY WHOLE #’S OF ATOMSCAN COMBINE TO FORM COMPNDS

• HE REASONED THAT ELEMENTS WERE COMPOSED OF ATOMS & THAT ONLY WHOLE #’S OF ATOMSCAN COMBINE TO FORM COMPNDS

8

DALTON’S THOUGHTSDALTON’S THOUGHTS• HIS IDEAS ARE NOW CALLED THE ATOMIC THEORY OF MATTER AND CAN BE SUMMARIZED AS:

• HIS IDEAS ARE NOW CALLED THE ATOMIC THEORY OF MATTER AND CAN BE SUMMARIZED AS:

1.ALL MATTER IS

COMPOSED OF

EXTREMELY SMALL

PARTICLES CALLED ATOMS

2.ATOMS OF A GIVEN

ELEMENT ARE IDENTICAL

IN SIZE, MASS, AND OTHER

PROPERTIES; ATOMS OF

DIFFERENT ELEMENTS

DIFFER IN SIZE, MASS, &

OTHER PROPERTIES

ELEMENT

2

ELEMENT

2

ELEMENT

3

ELEMENT

3

ELEMENT

4

ELEMENT

4

3.ATOMS CANNOT BE SUBDIVIDED, CREATED, OR DESTROYED

4.ATOMS OF DIFFERENT ELEMENTS COMBINE IN SIMPLE WHOLE # RATIOSTO FORM CHEM COMPDS

5.IN CHEMICAL RXNS, ATOMS ARE COMBINED, SEPARATED, OR REARRANGED

++ ++

9

DALTON AND HIS

CONTEMPORARIES

DALTON AND HIS

CONTEMPORARIES

THE EARLIEST THEORISTS

THOUGHT THE ATOM WAS

HARD AND ROUND,

MUCH LIKE TINY MARBLES

OR BALL BEARINGS.

THE EARLIEST THEORISTS

THOUGHT THE ATOM WAS

HARD AND ROUND,

MUCH LIKE TINY MARBLES

OR BALL BEARINGS.

STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• ALTHOUGH DALTON THOUGHT ATOMS WERE INDIVISIBLE, INVESTIGATORS IN THE LATE 1800’S PROVED OTHERWISE

• ALTHOUGH DALTON THOUGHT ATOMS WERE INDIVISIBLE, INVESTIGATORS IN THE LATE 1800’S PROVED OTHERWISE

STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• IT SOON BECAME CLEAR THAT ATOMS ARE ACTUALLY COMPOSED OF SEVERAL BASIC TYPES OF SMALLER PARTICLES

• IT SOON BECAME CLEAR THAT ATOMS ARE ACTUALLY COMPOSED OF SEVERAL BASIC TYPES OF SMALLER PARTICLES

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STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• AND IT’S THE NUMBERS AND ARRANGEMENTS OF THESE SUB-ATOMIC PARTICLES THAT DETERMINES THE IDENTITY OF THE ATOM.

• AND IT’S THE NUMBERS AND ARRANGEMENTS OF THESE SUB-ATOMIC PARTICLES THAT DETERMINES THE IDENTITY OF THE ATOM.

STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• THE FIRST DISCOVERY OF A SUBATOMIC PARTICLE RESULTED FROM THE INVESTIGATIONS INTO THE RELATIONSHIP BETWEEN ELECTRICITY AND MATTER.

• THE FIRST DISCOVERY OF A SUBATOMIC PARTICLE RESULTED FROM THE INVESTIGATIONS INTO THE RELATIONSHIP BETWEEN ELECTRICITY AND MATTER.

STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• IN THE LATE 1800’S, MANY EXPERIMENTS WERE PERFORMED IN WHICH ELECTRIC CURRENT WAS PASSED THROUGH VARIOUS GASES AT LOW PRESS

–CARRIED OUT IN TUBES CALLED CATHODE-RAY TUBES

• IN THE LATE 1800’S, MANY EXPERIMENTS WERE PERFORMED IN WHICH ELECTRIC CURRENT WAS PASSED THROUGH VARIOUS GASES AT LOW PRESS

–CARRIED OUT IN TUBES CALLED CATHODE-RAY TUBES

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STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• INVESTIGATORS NOTICED THAT WHEN CURRENT WAS PASSED THROUGH A CATHODE RAY TUBE, THE SURFACE OF THE TUBE DIRECTLY OPPOSITE THE CATHODE GLOWED.

• INVESTIGATORS NOTICED THAT WHEN CURRENT WAS PASSED THROUGH A CATHODE RAY TUBE, THE SURFACE OF THE TUBE DIRECTLY OPPOSITE THE CATHODE GLOWED.

STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• THEY HYPOTHESIZED THAT THE GLOW WAS CAUSED BY A STREAM OF PARTICLES

–THEY CALLED THE STREAM A CATHODE RAY

• THEY HYPOTHESIZED THAT THE GLOW WAS CAUSED BY A STREAM OF PARTICLES

–THEY CALLED THE STREAM A CATHODE RAY

STRUCTURE OF THE ATOMSTRUCTURE OF THE ATOM• THE CATHODE RAY TRAVELED FROM THE CATHODE TO THE ANODE WHEN CURRENT WAS PASSED THROUGH THE TUBE.

• THE CATHODE RAY TUBE OPENED THE DOOR FOR J.J. THOMPSON

• THE CATHODE RAY TRAVELED FROM THE CATHODE TO THE ANODE WHEN CURRENT WAS PASSED THROUGH THE TUBE.

• THE CATHODE RAY TUBE OPENED THE DOOR FOR J.J. THOMPSON

12

J. J. THOMPSONJ. J. THOMPSON

I PLAY WITH

ELECTRONS

• THOMPSON’S INVESTIGATIONS SUPPLIED EVIDENCE THAT THE CATHODE RAY COULD BE DEFLECTED BY APPLYING A POSITIVELY CHARGED ELECTRIC FIELD

–THIS HELPED THOMPSON DISC-OVER THAT THE CATHODE RAY WAS NEGATIVELY CHARGED.

• THOMPSON’S INVESTIGATIONS SUPPLIED EVIDENCE THAT THE CATHODE RAY COULD BE DEFLECTED BY APPLYING A POSITIVELY CHARGED ELECTRIC FIELD

–THIS HELPED THOMPSON DISC-OVER THAT THE CATHODE RAY WAS NEGATIVELY CHARGED.

J. J. THOMPSONJ. J. THOMPSON

13

• THOMPSON WAS ABLE TO MEASURE THE RATIO OF THE CHARGE OF CATHODE RAY PARTICLES TO THEIR MASS

–HE FOUND THAT THE RATIO WAS THE SAME REGARDLESS OF THE METAL USED AS THE CATHODE

• THOMPSON WAS ABLE TO MEASURE THE RATIO OF THE CHARGE OF CATHODE RAY PARTICLES TO THEIR MASS

–HE FOUND THAT THE RATIO WAS THE SAME REGARDLESS OF THE METAL USED AS THE CATHODE

• THOMPSON CONCLUDED THAT ALL CATHODE RAYS ARE COMPOSED OFIDENTICAL NEGATIVELY CHARGED PARTICLES

–WHICH WERE LATER CALLED ELECTRONS

• THOMPSON CONCLUDED THAT ALL CATHODE RAYS ARE COMPOSED OFIDENTICAL NEGATIVELY CHARGED PARTICLES

–WHICH WERE LATER CALLED ELECTRONS

• HE PROPOSED THAT THE ATOM LOOKS SOMETHING LIKE ACHOCOLATE CHIP COOKIE

• HE PROPOSED THAT THE ATOM LOOKS SOMETHING LIKE ACHOCOLATE CHIP COOKIE

THOMPSON’S ATOMIC MODELTHOMPSON’S ATOMIC MODEL

THE COOKIE PART IS POS. MATTER TO

CANCEL OUT THE NEG. ELECTRONS

THE COOKIE PART IS POS. MATTER TO

CANCEL OUT THE NEG. ELECTRONS

THE CHIPS WOULD BE

HIS ELECTRONS

THE CHIPS WOULD BE

HIS ELECTRONS

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• THOMPSON’S EXPERIMENTS REVEALED THAT THE ELECTRON HAS A VERY LARGE CHARGE IN RELATION TO ITS MASS

• THOMPSON’S EXPERIMENTS REVEALED THAT THE ELECTRON HAS A VERY LARGE CHARGE IN RELATION TO ITS MASS

• IN 1909, ROBERT MILLIKAN, PERFORMED AN INGENIOUS EXPERIMENT TO CALCULATE THEMASS OF AN ELECTRON

–HE DISCOVERED THAT THE MASS OF THE ELECTRON IS ABOUT 1/2000TH

THE MASS OF THE SIMPLEST ATOM (HYDRO.)

• IN 1909, ROBERT MILLIKAN, PERFORMED AN INGENIOUS EXPERIMENT TO CALCULATE THEMASS OF AN ELECTRON

–HE DISCOVERED THAT THE MASS OF THE ELECTRON IS ABOUT 1/2000TH

THE MASS OF THE SIMPLEST ATOM (HYDRO.)

HELLO, MILLIKANHELLO, MILLIKAN

DAT’S RIGHT!

I SAVED THE

DAY!

15

• HIS OIL DROP EXPERIMENT SHOWED THAT EVEN THOUGH THE ATOMS OF DIFFERENT ELEMENTS ARE VERY DIFFERENT, THEIR ELECTRONS ARE IDENTICAL.

–AN ELECTRON IS AN ELECTRON

–THE DIFFERENCE BETWEEN TWO DIFFERENT ATOMS IS THEIR NUMBER OF ELECTRONS NOT THEIR TYPE OF ELECTRON.

• HIS OIL DROP EXPERIMENT SHOWED THAT EVEN THOUGH THE ATOMS OF DIFFERENT ELEMENTS ARE VERY DIFFERENT, THEIR ELECTRONS ARE IDENTICAL.

–AN ELECTRON IS AN ELECTRON

–THE DIFFERENCE BETWEEN TWO DIFFERENT ATOMS IS THEIR NUMBER OF ELECTRONS NOT THEIR TYPE OF ELECTRON.

• HE ALSO CALCULATED THAT THE ELECTRON’S MASS IS 9.109x10-31kg

• HE ALSO CALCULATED THAT THE ELECTRON’S MASS IS 9.109x10-31kg

SO FAR WE’VE LEARNED…SO FAR WE’VE LEARNED…• THOMPSON’S & MILLIKAN’S IDEAS:

–ATOMS ARE IN FACT DIVISABLE

• THOMPSON’S & MILLIKAN’S IDEAS:

–ATOMS ARE IN FACT DIVISABLE

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–ELECTRONS ARE PRESENT IN ATOMS OF ALL ELEMENTS


–ELECTRONS ARE PRESENT IN ATOMS OF ALL ELEMENTS


–ONE OF THE ATOM’S FUNDEMENTAL PARTICLES IS NEGATIVELY CHARGED


–ONE OF THE ATOM’S FUNDEMENTAL PARTICLES IS NEGATIVELY CHARGED


–ATOMS ARE ELECTRICALLY NEUTRAL, SO THERE MUST BE A (+) CHARGE TO BALANCE OUT THE (–)


–ATOMS ARE ELECTRICALLY NEUTRAL, SO THERE MUST BE A (+) CHARGE TO BALANCE OUT THE (–)

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–BECAUSE ELECTRONS ARE BASICALLY MASSLESS THERE MUST BE SOMETHING ELSE THAT ACCOUNTS FOR THE ATOMS MASS.


–BECAUSE ELECTRONS ARE BASICALLY MASSLESS THERE MUST BE SOMETHING ELSE THAT ACCOUNTS FOR THE ATOMS MASS.

OTHER SIGNIFICANT DISCOVERIES…


• IN 1886, WHEN E. GOLDSTEIN OBSERVED A CATHODE-RAY TUBE AND FOUND RAYS TRAVELLING IN THE OPPOSITE DIRECTION OF THAT OF THE CATHODE RAYS

–HE CALLED THE RAYS CANAL RAYSAND CONCLUDED THAT THEY WERE COMPOSED OF POS. PARTICLES

• IN 1886, WHEN E. GOLDSTEIN OBSERVED A CATHODE-RAY TUBE AND FOUND RAYS TRAVELLING IN THE OPPOSITE DIRECTION OF THAT OF THE CATHODE RAYS

–HE CALLED THE RAYS CANAL RAYSAND CONCLUDED THAT THEY WERE COMPOSED OF POS. PARTICLES



• IT WAS SOON DISCOVERED THAT THE POSITIVE PARTICLES MASS IS ABOUT 2000 TIMESTHAT OF THE ELECTRON

• IT WAS SOON DISCOVERED THAT THE POSITIVE PARTICLES MASS IS ABOUT 2000 TIMESTHAT OF THE ELECTRON

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• IN 1932, THE ENGLISH PHYSICIST JAMES CHADWICK CONFIRMED THE EXISTANCE OF YET ANOTHER SUBATOMIC PARTICLE.

–THE NEUTRON, WHICH IS A PARTICLE WITH NO CHARGE

–HAS A MASS NEARLY EQUALTO THAT OF THE PROTON

• IN 1932, THE ENGLISH PHYSICIST JAMES CHADWICK CONFIRMED THE EXISTANCE OF YET ANOTHER SUBATOMIC PARTICLE.

–THE NEUTRON, WHICH IS A PARTICLE WITH NO CHARGE

–HAS A MASS NEARLY EQUALTO THAT OF THE PROTON



• THEREFORE THE SUBATOMIC PARTICLES ARE THE ELECTRON, PROTON, AND NEUTRON.

• THEREFORE THE SUBATOMIC PARTICLES ARE THE ELECTRON, PROTON, AND NEUTRON.



electron e- -1 0 9.11x10-28

proton p+ +1 1 1.67x10-24

neutron n0 0 1 1.67x10-24

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• WHEN SUBATOMIC PARTICLES WERE DISCOVERED, SCIENTISTS WONDERED HOW THESE PARTICLES WERE PUT TOGETHER IN AN ATOM.

• WHEN SUBATOMIC PARTICLES WERE DISCOVERED, SCIENTISTS WONDERED HOW THESE PARTICLES WERE PUT TOGETHER IN AN ATOM.

THE ATOMIC NUCLEUSTHE ATOMIC NUCLEUS

• THIS WAS A DIFFICULT QUESTION TO ANSWER, GIVEN HOW TINY ATOMS ARE.

• THIS WAS A DIFFICULT QUESTION TO ANSWER, GIVEN HOW TINY ATOMS ARE.


• MOST SCIENTISTS THOUGHT IT LIKELY THAT THE ELECTRONS WERE EVENLY DISTRIBUTED THROUGHOUT AN ATOM FILLED UNIFORMLY WITH POSITIVELY CHARGED MATERIAL.

• MOST SCIENTISTS THOUGHT IT LIKELY THAT THE ELECTRONS WERE EVENLY DISTRIBUTED THROUGHOUT AN ATOM FILLED UNIFORMLY WITH POSITIVELY CHARGED MATERIAL.


20

ERNEST RUTHERFORDERNEST RUTHERFORD

HOW IS THE

ATOM BUILT?

IN 1911, RUTHERFORD

PERFORMED ONE OF

THE MOST BRILLIANT

INVESTIGATIONS

EVER CONCIEVED.

IN 1911, RUTHERFORD

PERFORMED ONE OF

THE MOST BRILLIANT

INVESTIGATIONS

EVER CONCIEVED.

RUTHERFORD’S FAMOUS EXPERIMENT


• RUTHERFORD SET OUT TO TEST THE THOMPSON MODEL OF THE ATOM

• RUTHERFORD SET OUT TO TEST THE THOMPSON MODEL OF THE ATOM



• THE TEST USED RELATIVELY MASSIVE RADIOACTIVE ALPHA PARTICLES–ALPHA PARTICLES (αααα) ARE HELIUM ATOMS THAT HAVE LOST THEIR 2 ELECTRONS AND HAVE A DOUBLE POSITIVE CHARGE BECAUSE OF THE 2 REMAINING PROTONS

• THE TEST USED RELATIVELY MASSIVE RADIOACTIVE ALPHA PARTICLES–ALPHA PARTICLES (αααα) ARE HELIUM ATOMS THAT HAVE LOST THEIR 2 ELECTRONS AND HAVE A DOUBLE POSITIVE CHARGE BECAUSE OF THE 2 REMAINING PROTONS

21

• IN THE EXPERIMENT, RUTHERFORD DIRECTED A NARROW BEAM OF ALPHA PARTICLES AT A VERY THIN SHEET OF GOLD FOIL.–ACCORDING TO THE PREVAILING THEORY, THE ALPHA PARTICLES SHOULD HAVE PASSED EASILY THROUGH THE GOLD, WITH ONLY A SLIGHT DEFLECTION DUE TO THE POSITIVE CHARGE THOUGHT TO BE SPREAD OUT IN THE GOLD ATOMS.

• IN THE EXPERIMENT, RUTHERFORD DIRECTED A NARROW BEAM OF ALPHA PARTICLES AT A VERY THIN SHEET OF GOLD FOIL.–ACCORDING TO THE PREVAILING THEORY, THE ALPHA PARTICLES SHOULD HAVE PASSED EASILY THROUGH THE GOLD, WITH ONLY A SLIGHT DEFLECTION DUE TO THE POSITIVE CHARGE THOUGHT TO BE SPREAD OUT IN THE GOLD ATOMS.

22

WHAT HAPPENED?WHAT HAPPENED?• THE MAJORITY OF THE αααα PARTICLES PASSED STRAIGHT THROUGH THE GOLD ATOMS, WITHOUT ANY DEFLECTION

• THE MAJORITY OF THE αααα PARTICLES PASSED STRAIGHT THROUGH THE GOLD ATOMS, WITHOUT ANY DEFLECTION

WHAT HAPPENED?WHAT HAPPENED?• EVEN MORE SURPRISINGLY, A SMALL FRACTION OF THE ααααPARTICLES BOUNCED OFF THE GOLD FOIL ATOMS AT VERY LARGE ANGLES

• EVEN MORE SURPRISINGLY, A SMALL FRACTION OF THE ααααPARTICLES BOUNCED OFF THE GOLD FOIL ATOMS AT VERY LARGE ANGLES

23

WHAT HAPPENED?WHAT HAPPENED?• SOME EVEN BOUNCED BACK AT THE SOURCE

• SOME EVEN BOUNCED BACK AT THE SOURCE

• BASED ON THE RESULTS, RUTHERFORD SUGGESTED A NEW THEORY OF THE ATOM.

• BASED ON THE RESULTS, RUTHERFORD SUGGESTED A NEW THEORY OF THE ATOM.

• HE PROPOSED THAT THE ATOM ISMOSTLY EMPTY SPACE–THIS EXPLAINED THE LACK OF DEFLECTION OF SOME OF THE PARTICLES

• HE PROPOSED THAT THE ATOM ISMOSTLY EMPTY SPACE–THIS EXPLAINED THE LACK OF DEFLECTION OF SOME OF THE PARTICLES

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• HE CONCLUDED THAT ALL THE POSITIVE CHARGE AND ALMOST ALL THE MASS IS CONCENTRATED IN A SMALL CORE–HE CALLED THIS REGION THE NUCLEUS

• HE CONCLUDED THAT ALL THE POSITIVE CHARGE AND ALMOST ALL THE MASS IS CONCENTRATED IN A SMALL CORE–HE CALLED THIS REGION THE NUCLEUS

NIELS BOHR

25

NIELS BOHR

I play with light!

Bohr

• Refined Rutherford’s idea

–Added ORBITS like planets

orbiting the sun

–Orbits = Energy Levels or Shells

or Shields

• Refined Rutherford’s idea

–Added ORBITS like planets

orbiting the sun

–Orbits = Energy Levels or Shells

or Shields

Bohr’s Atom

electrons in orbits

nucleus

26

ENERGY LEVELS

• Energy level Maximum # e-

–1st 2

–2nd 8

–3rd 18

–4th 32

• Energy level Maximum # e-

–1st 2

–2nd 8

–3rd 18

–4th 32

A LITTLE REVIEW!A LITTLE REVIEW!• THERE ARE THREE FUNDAMENTAL PARTICLES THAT TOGETHER MAKE UP THE ATOM.–COMPOSED OF ELECTRONS, PROTONS, AND NEUTRONS

• THERE ARE THREE FUNDAMENTAL PARTICLES THAT TOGETHER MAKE UP THE ATOM.–COMPOSED OF ELECTRONS, PROTONS, AND NEUTRONS

A LITTLE REVIEW!A LITTLE REVIEW!• THE PROTONS AND THE NEUTRONS MAKE UP THE CENTER OF THE ATOM–CENTER OF THE ATOM IS CALLED THE NUCLEUS

• THE PROTONS AND THE NEUTRONS MAKE UP THE CENTER OF THE ATOM–CENTER OF THE ATOM IS CALLED THE NUCLEUS

27

A LITTLE REVIEW!A LITTLE REVIEW!• THE PROTONS & NEUTRONS OCC-UPY THE MASS OF THE ATOM

• THE PROTONS & NEUTRONS OCC-UPY THE MASS OF THE ATOM

• THE ELECTRONS SURROUND THE NUCLEUS AND OCCUPY MOST OF THE ATOM’S VOLUME

• THE ELECTRONS SURROUND THE NUCLEUS AND OCCUPY MOST OF THE ATOM’S VOLUME

• HOW, THEN, ARE ATOMS OF HYDROGEN DIFFERENT FROM THOSE OF OXYGEN?

–A SUBATOMIC PARTICLES FROM ONE TYPE OF ATOM LOOKS LIKE PARTICLES FROM OTHER ATOMS

• HOW, THEN, ARE ATOMS OF HYDROGEN DIFFERENT FROM THOSE OF OXYGEN?

–A SUBATOMIC PARTICLES FROM ONE TYPE OF ATOM LOOKS LIKE PARTICLES FROM OTHER ATOMS

28

• IT’S THE NUMBERS OF PROTONS IN AN ATOM THAT MAKES ATOMS DIFFERENT.

–AN OXYGEN ATOM HAS 8 PROTONSIN ITS NUCLEUS

–A HYDROGEN ATOM HAS 1 PROTONIN ITS NUCLEUS

• IT’S THE NUMBERS OF PROTONS IN AN ATOM THAT MAKES ATOMS DIFFERENT.

–AN OXYGEN ATOM HAS 8 PROTONSIN ITS NUCLEUS

–A HYDROGEN ATOM HAS 1 PROTONIN ITS NUCLEUS

• THE ATOMIC NUMBER OF AN ELEMENT IS THE NUMBER OF PROTONS IN THE NUCLEUS OF AN ATOM OF THAT ELEMENT

–SINCE OXYGEN’S NUCLEUS HAS 8 PROTONS ITS ATOMIC # IS 8

• THE ATOMIC NUMBER OF AN ELEMENT IS THE NUMBER OF PROTONS IN THE NUCLEUS OF AN ATOM OF THAT ELEMENT

–SINCE OXYGEN’S NUCLEUS HAS 8 PROTONS ITS ATOMIC # IS 8

• THE PROTONS IDENTIFY THE TYPEOF ATOM, THE ONLY ATOM WITH 8 PROTONS IS OXYGEN

• THE PROTONS IDENTIFY THE TYPEOF ATOM, THE ONLY ATOM WITH 8 PROTONS IS OXYGEN

29

ATOMS OF THE 1STTEN ATOMS

Hydrogen H 1 1 0 1 1

Helium He 2 2 2 4 2

Lithium Li 3 3 4 7 3

Beryllium Be 4 4 5 9 4

Boron B 5 5 6 11 5

Carbon C 6 6 6 12 6

Nitrogen N 7 7 7 14 7

Oxygen O 8 8 8 16 8

Fluorine F 9 9 10 19 9

Neon Ne 10 10 10 20 10

• FOR EACH ELEMENT LISTED, THE NUMBER OF PROTONS EQUALS THE NUMBER OF ELECTRONS

–REMEMBER ATOMS ARE ELECTRICALLY NEUTRAL

• FOR EACH ELEMENT LISTED, THE NUMBER OF PROTONS EQUALS THE NUMBER OF ELECTRONS

–REMEMBER ATOMS ARE ELECTRICALLY NEUTRAL

30



Helium He 2 2 2 4 2



Boron B 5 5 6 11 5

Carbon C 6 6 6 12 6


Oxygen O 8 8 8 16 8


Neon Ne 10 10 10 20 10

• IN AN ATOM, THE NUMBER OF ELECTRONS MUST EQUAL THE NUMBER OF PROTONS

• A HYDROGEN ATOM HAS 1 ELECTRN• AN OXYGEN ATOM HAS 8 ELECTRNS

• IN AN ATOM, THE NUMBER OF ELECTRONS MUST EQUAL THE NUMBER OF PROTONS

• A HYDROGEN ATOM HAS 1 ELECTRN• AN OXYGEN ATOM HAS 8 ELECTRNS

• THE MASS OF AN ATOM IS CONCENTRATED IN ITS NUCLEUS AND DEPENDS ON THE NUMER OF PROTONS AND NEUTRONS

• MASS # = #P+ + #NO

• THE MASS OF AN ATOM IS CONCENTRATED IN ITS NUCLEUS AND DEPENDS ON THE NUMER OF PROTONS AND NEUTRONS

• MASS # = #P+ + #NO

31



Helium He 2 2 2 4 2



Boron B 5 5 6 11 5

Carbon C 6 6 6 12 6


Oxygen O 8 8 8 16 8


Neon Ne 10 10 10 20 10

• THE COMPOSITION OF ANY ATOM CAN BE REPRESENTED IN SHORTHAND NOTATION:

• THE COMPOSITION OF ANY ATOM CAN BE REPRESENTED IN SHORTHAND NOTATION:

CHEMICAL COMPOSITION SHORTHAND

CHEMICAL COMPOSITION SHORTHAND

ClCl3535

1717

MASS

NUMBER

MASS

NUMBER

ATOMIC

NUMBER

ATOMIC

NUMBER

NUMBER OF

PROTONS

NUMBER OF

PROTONS

# OF PROTONS+

# OF NEUTRONS

# OF PROTONS+

# OF NEUTRONS

32

• EVERY CHLORINE ATOM HAS 17 PROTONS, WITHOUT EXCEPTION, –HOWEVER, NOT EVERY CHLORINE ATOM HAS 18 NEUTRONS.

–ATOMS WITH THE SAME NUMBER OF PROTONS BUT CONTAIN DIFFERENT NUMBERS OF NEUTRONS ARE CALLED ISOTOPES.

• EVERY CHLORINE ATOM HAS 17 PROTONS, WITHOUT EXCEPTION, –HOWEVER, NOT EVERY CHLORINE ATOM HAS 18 NEUTRONS.

–ATOMS WITH THE SAME NUMBER OF PROTONS BUT CONTAIN DIFFERENT NUMBERS OF NEUTRONS ARE CALLED ISOTOPES.

ISOTOPESISOTOPES

• BECAUSE ISOTOPES OF AN ELEMENT HAVE DIFFERENT NUMBERS OF NEUTRONS THEY HAVEDIFFERENT MASS NUMBERS.

• BECAUSE ISOTOPES OF AN ELEMENT HAVE DIFFERENT NUMBERS OF NEUTRONS THEY HAVEDIFFERENT MASS NUMBERS.

ISOTOPESISOTOPES

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• ISOTOPES ARE CHEMICALLY ALIKE BECAUSE THEY HAVE IDENTICAL NUMBERS OF PROTONS AND ELECTRONS– IT’S THE ELECTRONS AND PROTONS THAT ARE RESPONSIBLE FOR CHEMICAL BEHAVIOR

• ISOTOPES ARE CHEMICALLY ALIKE BECAUSE THEY HAVE IDENTICAL NUMBERS OF PROTONS AND ELECTRONS– IT’S THE ELECTRONS AND PROTONS THAT ARE RESPONSIBLE FOR CHEMICAL BEHAVIOR

proton

neutronneutron

electronelectron

BERYLLIUM

ISOTOPES

BERYLLIUM

ISOTOPES

EXAMPLE OF AN

ISOTOPE

EXAMPLE OF AN

ISOTOPE

ClCl3535

1717 ClCl3737

1717

20 20 NEUTRONSNEUTRONS

ATOMIC MASS

1818 NEUTRONSNEUTRONS

ATOMIC NUMBER

34

IONSIONS• AN ELEMENT’S ATOMS ARE NOT ALWAYS NEUTRAL IN CHARGE.–WHEN AN ATOM LOSES OR GAINS ONE OR MORE OF ITS ELECTRONS IT BECOMES ION.

• AN ELEMENT’S ATOMS ARE NOT ALWAYS NEUTRAL IN CHARGE.–WHEN AN ATOM LOSES OR GAINS ONE OR MORE OF ITS ELECTRONS IT BECOMES ION.

IONSIONS• AN ION THAT HAS MORE ELECTRONS THAN PROTONS HAS ANEGATIVE ELECTRICAL CHARGE

• AN ION THAT HAS MORE ELECTRONS THAN PROTONS HAS ANEGATIVE ELECTRICAL CHARGE

IONSIONS• AN ION THAT HAS FEWER ELECTRONS THAN PROTONS HAS A POSITIVE ELECTRICAL CHARGE

• AN ION THAT HAS FEWER ELECTRONS THAN PROTONS HAS A POSITIVE ELECTRICAL CHARGE

35

IONSIONS

NOTE: IT’S THE PROTONS THAT DEFINE THE TYPE OF ATOM IT IS, BUT THE ELECTRONS DEFINE THE ATOM’S CHARGE.

NOTE: IT’S THE PROTONS THAT DEFINE THE TYPE OF ATOM IT IS, BUT THE ELECTRONS DEFINE THE ATOM’S CHARGE.

SOME ATOMS

GAIN ELECTRONS

SOME ATOMS

GAIN ELECTRONS

O

--

----

--

--

--

--

--

O-2

--

----

--

--

--

--

--

----

ATOM’S IONIC CHARGE =

# PROTONS - # ELECTRONS

ATOM’S IONIC CHARGE =


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ATOMS, IONS, AND ISOTOPES

ATOMS

NEUTRAL AND ARE DEFINED BY THE # OF PROTONS IN THEIR

NUCLEUS

3 p+ = Li ATOM, ETC.

IONS

HAVE AN ELECTRICAL CHARGE DETERMINED BY


N-2 = 7 p+ - 9 e- ; ETC.

ISOTOPES

TWO ATOMS WITH THE SAME # OF PROTONS, BUT DIFFERENT #’S OF

NEUTRONS OR MASSES

CALCIUM-40 & CALCIUM-44

the structure of the atom - parkway · pdf file1 the structure of the atom atomic models...

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