the structure of the atom atomic models pioneers of the atom democritus lavoisier dalton thompson...
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THE STRUCTURE OF THE ATOM
THE STRUCTURE OF THE ATOM
ATOMIC MODELSATOMIC MODELS
PIONEERS OF THE ATOM
PIONEERS OF THE ATOM
•DEMOCRITUS•LAVOISIER•DALTON•THOMPSON
•MILLIKEN•RUTHERFORD
•DEMOCRITUS•LAVOISIER•DALTON•THOMPSON
•MILLIKEN•RUTHERFORD
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...
DEMOCRITUSDEMOCRITUS•WAS A GREEK PHILOSOPHER THAT
BEGAN WONDERING WHAT WAS THE UNIVERSE MADE UP OF.
•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…
•WAS A GREEK PHILOSOPHER THAT BEGAN WONDERING WHAT WAS THE UNIVERSE MADE UP OF.
•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 = SCEPTIC
ARISTOTLE = SCEPTIC
DEMOCRITUS ISDEMOCRITUS ISANAN
IGNORAMUS!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 = SCEPTIC
ARISTOTLE = SCEPTIC
DEMOCRITUS ISDEMOCRITUS ISANAN
IGNORAMUS!IGNORAMUS!
ARISTOTLE BELIEVED THAT MATTER WAS CONTINUOUS.
ARISTOTLE BELIEVED THAT MATTER WAS CONTINUOUS.
DEMOCRITUS’ ATOMS
DEMOCRITUS’ ATOMS
SO...CHEMISTRY DIED FOR ABOUT 1400
YEARS
SO...CHEMISTRY DIED FOR ABOUT 1400
YEARS
UNTIL...UNTIL...
SO...CHEMISTRY DIED FOR ABOUT 1400
YEARS
SO...CHEMISTRY DIED FOR ABOUT 1400
YEARS
IN THE1700’S IN THE1700’S
FOUNDATIONS OF ATOMIC THEORY
FOUNDATIONS 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
• 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.
•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.
FOUNDATIONS OF ATOMIC THEORY
FOUNDATIONS OF ATOMIC THEORY
•HOWEVER, THERE WAS CONTROVERSY AS TO WHETHER ELEMENTS ALWAYS COMBINE IN THE SAME RATIO WHEN FORMING A PARTICULAR COMPOUND.
• 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
•HOWEVER, THERE WAS CONTROVERSY AS TO WHETHER ELEMENTS ALWAYS COMBINE IN THE SAME RATIO WHEN FORMING A PARTICULAR COMPOUND.
• 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 BEMATTER CAN BENEITHER CREATED NEITHER CREATED NOR DESTROYED.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 BEMATTER CAN BENEITHER CREATED NEITHER CREATED NOR DESTROYED.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
THE LAW OF THE LAW OF DEFINITE DEFINITE
PROPORTIONPROPORTION
THE LAW OF THE LAW OF MULTIPLE MULTIPLE
PROPORTIONPROPORTIONSS
I’M BETTER I’M BETTER LOOKING LOOKING
THAN THAN PROUST!PROUST!
LAW OF LAW OF DEFINITE DEFINITE PROPOR-PROPOR-
TIONSTIONS
A CHEM COMPD IS ALWAYS A CHEM COMPD IS ALWAYS COMPOSED OF THE SAME COMPOSED OF THE SAME
ELEM. IN THE SAME PROPOR. ELEM. IN THE SAME PROPOR. BY MASSBY MASS
LAW OF LAW OF MULTIPLE MULTIPLE PROPOR-PROPOR-
TIONSTIONS
IF 2 DIFFERENT COMPDS ARE IF 2 DIFFERENT COMPDS ARE COMPOSED OF THE SAME 2 COMPOSED OF THE SAME 2
ELEMTS, THEN THE RATIO OF ELEMTS, THEN THE RATIO OF OF THE ELEMNTS IS ALWAYS OF THE ELEMNTS IS ALWAYS A RATIO OF SMALL WHOLE A RATIO OF SMALL WHOLE
#’S#’S
++++ ====CC OO COCO
CARBON CARBON MONOXIDEMONOXIDECARBON CARBON
MONOXIDEMONOXIDE
++++ ====CC OO COCO
CARBON CARBON MONOXIDEMONOXIDECARBON CARBON
MONOXIDEMONOXIDE
++++ ====CC OO COCO22
CARBON CARBON DIOXIDEDIOXIDECARBON CARBON DIOXIDEDIOXIDE
++++OO
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.
•HE REASONED THAT ELEMENTS WERE COMPOSED OF ATOMS & THAT ONLY WHOLE #’S OF ATOMS CAN COMBINE TO FORM COMPNDS
•HIS IDEAS ARE NOW CALLED THE ATOMIC THEORY OF MATTER AND CAN BE SUMMARIZED AS:
• 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.
•HE REASONED THAT ELEMENTS WERE COMPOSED OF ATOMS & THAT ONLY WHOLE #’S OF ATOMS CAN COMBINE TO FORM COMPNDS
•HIS IDEAS ARE NOW CALLED THE ATOMIC THEORY OF MATTER AND CAN BE SUMMARIZED AS:
1.1.ALL MATTER IS ALL MATTER IS COMPOSED OF COMPOSED OF EXTREMELY SMALL EXTREMELY SMALL PARTICLES CALLED PARTICLES CALLED ATOMSATOMS
2.2.ATOMS OF A GIVEN ATOMS OF A GIVEN ELEMENT ARE ELEMENT ARE IDENTICAL IDENTICAL IN SIZE, MASSIN SIZE, MASS, AND , AND OTHER PROPERTIES; OTHER PROPERTIES; ATOMS OF DIFFERENT ATOMS OF DIFFERENT ELEMENTS DIFFER IN ELEMENTS DIFFER IN SIZE, MASS, & OTHER SIZE, MASS, & OTHER PROPERTIESPROPERTIES
ELEMENT2
ELEMENT2
ELEMENT 3
ELEMENT 3
ELEMENT 1
ELEMENT 1
ELEMENT4
ELEMENT4
3.3.ATOMS CANNOT BE ATOMS CANNOT BE SUBDIVIDED, SUBDIVIDED, CREATED, OR CREATED, OR DESTROYEDDESTROYED
4.4.ATOMS OF ATOMS OF DIFFERENT DIFFERENT ELEMENTS COMBINE ELEMENTS COMBINE IN SIMPLE IN SIMPLE WHOLE # WHOLE # RATIOSRATIOS TO FORM TO FORM CHEM COMPDSCHEM COMPDS
5.5.IN CHEMICAL RXNS, IN CHEMICAL RXNS, ATOMS ARE ATOMS ARE COMBINED, COMBINED, SEPARATED, OR SEPARATED, OR REARRANGEDREARRANGED
++++ ++++
DALTON AND HIS CONTEMPORARIESDALTON 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 ATOM
STRUCTURE OF THE ATOM
•ALTHOUGH DALTON THOUGHT ATOMS WERE INDIVISIBLE, INVESTIGATORS IN THE LATE 1800’S PROVED OTHERWISE
• IT SOON BECAME CLEAR THAT ATOMS ARE ACTUALLY COMPOSED OF SEVERAL BASIC TYPES OF SMALLER PARTICLES
•AND IT’S THE NUMBERS AND ARRANGEMENTS OF THESE SUB-ATOMIC PARTICLES THAT DETERMINES THE IDENTITY OF THE ATOM.
•ALTHOUGH DALTON THOUGHT ATOMS WERE INDIVISIBLE, INVESTIGATORS IN THE LATE 1800’S PROVED OTHERWISE
• IT SOON BECAME CLEAR THAT ATOMS ARE ACTUALLY COMPOSED OF SEVERAL BASIC TYPES OF SMALLER PARTICLES
•AND IT’S THE NUMBERS AND ARRANGEMENTS OF THESE SUB-ATOMIC PARTICLES THAT DETERMINES THE IDENTITY OF THE ATOM.
STRUCTURE OF THE ATOM
STRUCTURE OF THE ATOM
•THE FIRST DISCOVERY OF A SUBATOMIC PARTICLE RESULTED FROM THE INVESTIGATIONS INTO THE RELATIONSHIP BETWEEN ELECTRICITY AND MATTER.
• 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
•THE FIRST DISCOVERY OF A SUBATOMIC PARTICLE RESULTED FROM THE INVESTIGATIONS INTO THE RELATIONSHIP BETWEEN ELECTRICITY AND MATTER.
• 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
STRUCTURE OF THE ATOM
STRUCTURE 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 ATOM
STRUCTURE 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 ATOM
STRUCTURE 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
J. J. THOMPSONJ. J. THOMPSON
I PLAY WITHELECTRONS
•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
•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 OF IDENTICAL NEGATIVELY CHARGED PARTICLES–WHICH WERE LATER CALLED ELECTRONS
•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 OF IDENTICAL NEGATIVELY CHARGED PARTICLES–WHICH WERE LATER CALLED ELECTRONS
•HE PROPOSED THAT THE ATOM LOOKS SOMETHING LIKE A CHOCOLATE CHIP COOKIE
•HE PROPOSED THAT THE ATOM LOOKS SOMETHING LIKE A CHOCOLATE CHIP COOKIE
THOMPSON’S ATOMIC MODEL
THOMPSON’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 BEHIS ELECTRONS
THE CHIPS WOULD BEHIS ELECTRONS
•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 THE MASS OF AN ELECTRON–HE DISCOVERED THAT THE MASS OF THE ELECTRON IS ABOUT 1/2000TH THE MASS OF THE SIMPLEST ATOM (HYDRO.)
•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 THE MASS 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!DAT’S RIGHT!I SAVED THEI SAVED THE
DAY!DAY!
•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
•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
SO FAR WE’VE LEARNED…SO FAR WE’VE LEARNED…•THOMPSON’S & MILLIKAN’S IDEAS:
–ATOMS ARE IN FACT DIVISABLE–ELECTRONS ARE PRESENT IN ATOMS OF ALL ELEM.
–ONE OF THE ATOM’S FUNDMNTL PARTICLES IS NEG. CHARGED
–ATOMS ARE ELECTRICALLY NEUTRAL, SO THERE MUST BE A (+) CHARGE TO BALANCE OUT THE (–)
–BECAUSE ELECTRONS ARE BASICALLY MASSLESS THERE MUST BE SOMETHING ELSE THAT ACCOUNTS FOR THE ATOMS MASS.
•THOMPSON’S & MILLIKAN’S IDEAS:–ATOMS ARE IN FACT DIVISABLE–ELECTRONS ARE PRESENT IN ATOMS OF ALL ELEM.
–ONE OF THE ATOM’S FUNDMNTL PARTICLES IS NEG. CHARGED
–ATOMS ARE ELECTRICALLY NEUTRAL, SO THERE MUST BE A (+) CHARGE TO BALANCE OUT THE (–)
–BECAUSE ELECTRONS ARE BASICALLY MASSLESS THERE MUST BE SOMETHING ELSE THAT ACCOUNTS FOR THE ATOMS MASS.
OTHER SIGNIFICANT DISCOVERIES…
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 RAYS AND CONCLUDED THAT THEY WERE COMPOSED OF POS. PARTICLES
• IT WAS SOON DISCOVERED THAT THE POSITIVE PARTICLES MASS IS ABOUT 2000 TIMES THAT OF THE ELECTRON
• 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 RAYS AND CONCLUDED THAT THEY WERE COMPOSED OF POS. PARTICLES
• IT WAS SOON DISCOVERED THAT THE POSITIVE PARTICLES MASS IS ABOUT 2000 TIMES THAT OF THE ELECTRON
• 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 EQUAL TO THAT OF THE PROTON
•THEREFORE THE SUBATOMIC PARTICLES ARE THE ELECTRON, PROTON, AND NEUTRON.
• 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 EQUAL TO THAT OF THE PROTON
•THEREFORE THE SUBATOMIC PARTICLES ARE THE ELECTRON, PROTON, AND NEUTRON.
OTHER SIGNIFICANT DISCOVERIES…
OTHER SIGNIFICANT DISCOVERIES…
electroelectronn ee-- -1-1 00 9.11x109.11x10--
2828
protonproton pp++ +1+1 11 1.67x101.67x10--
2424
neutroneutronn nn00 00 11 1.67x101.67x10--
2424
•WHEN SUBATOMIC PARTICLES WERE DISCOVERED, SCIENTISTS WONDERED HOW THESE PARTICLES WERE PUT TOGETHER IN AN ATOM.
•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.
•WHEN SUBATOMIC PARTICLES WERE DISCOVERED, SCIENTISTS WONDERED HOW THESE PARTICLES WERE PUT TOGETHER IN AN ATOM.
•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.
THE ATOMIC NUCLEUSTHE ATOMIC NUCLEUS
ERNEST RUTHERFORD
ERNEST RUTHERFORD
HOW IS THE HOW IS THE ATOM BUILT?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’S FAMOUS EXPERIMENT
•RUTHERFORD SET OUT TO TEST THE THOMPSON MODEL OF THE ATOM
•THE TEST USED RELATIVELY MASSIVE RADIOACTIVE ALPHA PARTICLES–ALPHA PARTICLES () ARE HELIUM ATOMS THAT HAVE LOST THEIR 2 ELECTRONS AND HAVE A DOUBLE POSITIVE CHARGE BECAUSE OF THE 2 REMAINING PROTONS
•RUTHERFORD SET OUT TO TEST THE THOMPSON MODEL OF THE ATOM
•THE TEST USED RELATIVELY MASSIVE RADIOACTIVE ALPHA PARTICLES–ALPHA PARTICLES () ARE HELIUM ATOMS THAT HAVE LOST THEIR 2 ELECTRONS AND HAVE A DOUBLE POSITIVE CHARGE BECAUSE OF THE 2 REMAINING PROTONS
•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.
WHAT HAPPENED?WHAT HAPPENED?•THE MAJORITY OF THE PARTICLES PASSED STRAIGHT THROUGH THE GOLD ATOMS, WITHOUT ANY DEFLECTION
•EVEN MORE SURPRISINGLY, A SMALL FRACTION OF THE PARTICLES BOUNCED OFF THE GOLD FOIL ATOMS AT VERY LARGE ANGLES
•SOME EVEN BOUNCED BACK AT THE SOURCE
•THE MAJORITY OF THE PARTICLES PASSED STRAIGHT THROUGH THE GOLD ATOMS, WITHOUT ANY DEFLECTION
•EVEN MORE SURPRISINGLY, A SMALL FRACTION OF THE PARTICLES BOUNCED OFF THE GOLD FOIL ATOMS AT VERY LARGE ANGLES
•SOME EVEN BOUNCED BACK AT THE SOURCE
•BASED ON THE RESULTS, RUTHERFORD SUGGESTED A NEW THEORY OF THE ATOM.
•HE PROPOSED THAT THE ATOM IS MOSTLY EMPTY SPACE–THIS EXPLAINED THE LACK OF DEFLECTION OF SOME OF THE PARTICLES
•HE CONCLUDED THAT ALL THE POSITIVE CHARGE AND ALMOST ALL THE MASS IS CONCENTRATED IN A SMALL CORE–HE CALLED THIS REGION THE NUCLEUS
•BASED ON THE RESULTS, RUTHERFORD SUGGESTED A NEW THEORY OF THE ATOM.
•HE PROPOSED THAT THE ATOM IS MOSTLY EMPTY SPACE–THIS EXPLAINED THE LACK OF DEFLECTION OF SOME OF THE PARTICLES
•HE CONCLUDED THAT ALL THE POSITIVE CHARGE AND ALMOST ALL THE MASS IS CONCENTRATED IN A SMALL CORE–HE CALLED THIS REGION THE NUCLEUS
A LITTLE REVIEW!A LITTLE REVIEW!•THERE ARE THREE FUNDAMENTAL PARTICLES THAT TOGETHER MAKE UP THE ATOM.–COMPOSED OF ELECTRONS, PROTONS, AND NEUTRONS
•THE PROTONS AND THE NEUTRONS MAKE UP THE CENTER OF THE ATOM–CENTER OF THE ATOM IS CALLED THE NUCLEUS
•THE PROTONS & NEUTRONS OCC-UPY THE MASS OF THE ATOM
•THERE ARE THREE FUNDAMENTAL PARTICLES THAT TOGETHER MAKE UP THE ATOM.–COMPOSED OF ELECTRONS, PROTONS, AND NEUTRONS
•THE PROTONS AND THE NEUTRONS MAKE UP THE CENTER OF THE ATOM–CENTER OF THE ATOM IS CALLED THE NUCLEUS
•THE PROTONS & NEUTRONS OCC-UPY THE MASS OF THE ATOM
•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
•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
•IT’S THE NUMBERS OF PROTONS IN AN ATOM THAT MAKES ATOMS DIFFERENT.–AN OXYGEN ATOM HAS 8 PROTONS IN ITS NUCLEUS
–A HYDROGEN ATOM HAS 1 PROTON IN 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 PROTONS IDENTIFY THE TYPE OF ATOM, THE ONLY ATOM WITH 8 PROTONS IS OXYGEN
•IT’S THE NUMBERS OF PROTONS IN AN ATOM THAT MAKES ATOMS DIFFERENT.–AN OXYGEN ATOM HAS 8 PROTONS IN ITS NUCLEUS
–A HYDROGEN ATOM HAS 1 PROTON IN 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 PROTONS IDENTIFY THE TYPE OF ATOM, THE ONLY ATOM WITH 8 PROTONS IS OXYGEN
ATOMS OF THE 1ATOMS OF THE 1STST TEN ATOMS TEN ATOMS
HydrogeHydrogenn HH 11 11 00 11 11
HeliumHelium HeHe 22 22 22 44 22LithiumLithium LiLi 33 33 44 77 33BerylliuBerylliu
mm BeBe 44 44 55 99 44
BoronBoron BB 55 55 66 1111 55CarbonCarbon CC 66 66 66 1212 66
NitrogenNitrogen NN 77 77 77 1414 77OxygenOxygen OO 88 88 88 1616 88FluorineFluorine FF 99 99 1010 1919 99
NeonNeon NeNe 1010 1010 1010 2020 1010
•FOR EACH ELEMENT LISTED, THE NUMBER OF PROTONS EQUALS THE NUMBER OF ELECTRONS–REMEMBER ATOMS ARE ELECTRICALLY NEUTRAL
•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 CONCEN. IN ITS NUCLEUS AND DEPENDS ON THE NUMER OF PROTONS AND NEUTRONS
•FOR EACH ELEMENT LISTED, THE NUMBER OF PROTONS EQUALS THE NUMBER OF ELECTRONS–REMEMBER ATOMS ARE ELECTRICALLY NEUTRAL
•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 CONCEN. IN ITS NUCLEUS AND DEPENDS ON THE NUMER OF PROTONS AND NEUTRONS
•THE TOTAL NUMBER OF PROTONS AND NEUTRONS IN AN ATOM IS CALLED THE MASS NUMBER–A CARBON ATOM, WHICH HAS 6 PROTONS AND 6 NEUTRONS, HAS A MASS NUMBER OF 12
•IF YOU KNOW THE ATOMIC NUMBER AND MASS NUMBER OF AN ATOM OF ANY ELEMENT, YOU CAN DETERMINE THE ATOM’S COMPOSITION
•THE COMPOSITION OF ANY ATOM CAN BE REPRESENTED IN SHORTHAND NOTATION:
•THE TOTAL NUMBER OF PROTONS AND NEUTRONS IN AN ATOM IS CALLED THE MASS NUMBER–A CARBON ATOM, WHICH HAS 6 PROTONS AND 6 NEUTRONS, HAS A MASS NUMBER OF 12
•IF YOU KNOW THE ATOMIC NUMBER AND MASS NUMBER OF AN ATOM OF ANY ELEMENT, YOU CAN DETERMINE THE ATOM’S COMPOSITION
•THE COMPOSITION OF ANY ATOM CAN BE REPRESENTED IN SHORTHAND NOTATION:
CHEMICAL COMPOSITION SHORTHAND
CHEMICAL COMPOSITION SHORTHAND
ClCl3535
1717
MASS MASS NUMBERNUMBER
MASS MASS NUMBERNUMBER
ATOMIC ATOMIC NUMBERNUMBERATOMIC ATOMIC NUMBERNUMBER
NUMBER OF NUMBER OF PROTONSPROTONS
NUMBER OF NUMBER OF PROTONSPROTONS
# OF PROTONS# OF PROTONS++
# OF NEUTRONS# OF NEUTRONS
# OF PROTONS# OF PROTONS++
# OF NEUTRONS# OF NEUTRONS
•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.
•BECAUSE ISOTOPES OF AN ELEMENT HAVE DIFFERENT NUMBERS OF NEUTRONS THEY HAVE DIFFERENT MASS NUMBERS.
•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.
•BECAUSE ISOTOPES OF AN ELEMENT HAVE DIFFERENT NUMBERS OF NEUTRONS THEY HAVE DIFFERENT MASS NUMBERS.
ISOTOPESISOTOPES
•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
protonproton
neutronneutron
electronelectron
BERYLLIUMISOTOPES
BERYLLIUMISOTOPES
EXAMPLE OF AN ISOTOPE
EXAMPLE OF AN ISOTOPE
ClCl3535
1717 ClCl3737
1717
20 20 NEUTRONSNEUTRONS
ATOMIC MASSATOMIC MASS
1818 NEUTRONSNEUTRONS
ATOMIC NUMBERATOMIC NUMBERATOMIC NUMBERATOMIC NUMBER
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 ION THAT HAS MORE ELECTRONS THAN PROTONS HAS A NEGATIVE ELECTRICAL CHARGE
•AN ION THAT HAS FEWER ELECTRONS THAN PROTONS HAS A POSITIVE ELECTRICAL CHARGE
•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 ION THAT HAS MORE ELECTRONS THAN PROTONS HAS A NEGATIVE ELECTRICAL CHARGE
•AN ION THAT HAS FEWER ELECTRONS THAN PROTONS HAS A POSITIVE ELECTRICAL CHARGE
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
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ATOM’S IONIC CHARGE = ATOM’S IONIC CHARGE = # PROTONS - # ELECTRONS # PROTONS - # ELECTRONS
ATOM’S IONIC CHARGE = ATOM’S IONIC CHARGE = # PROTONS - # ELECTRONS # PROTONS - # ELECTRONS
ATOMS, IONS, AND ISOTOPESATOMS, IONS, AND ISOTOPES
ATOMSATOMS
NEUTRAL AND ARE DEFINED BY NEUTRAL AND ARE DEFINED BY THE # OF PROTONS IN THEIR THE # OF PROTONS IN THEIR
NUCLEUSNUCLEUS
3 p3 p++ = Li ATOM, ETC. = Li ATOM, ETC.
IONSIONS
HAVE AN ELECTRICAL CHARGE HAVE AN ELECTRICAL CHARGE DETERMINED BY DETERMINED BY
# PROTONS - # # PROTONS - # ELECTRONSELECTRONS
NN-2 -2 = 7 p= 7 p++ - 9 e - 9 e- - ; ETC.; ETC.
ISOTOPESISOTOPES
TWO ATOMS WITH THE SAME # TWO ATOMS WITH THE SAME # OF PROTONS, BUT DIFFERENT OF PROTONS, BUT DIFFERENT #’S OF NEUTRONS OR MASSES#’S OF NEUTRONS OR MASSES
CALCIUM-40 & CALCIUM-CALCIUM-40 & CALCIUM-4444