THE STRUCTURE OF THE ATOM ATOMIC MODELS PIONEERS OF THE ATOM DEMOCRITUS LAVOISIER DALTON THOMPSON MILLIKEN RUTHERFORD DEMOCRITUS LAVOISIER DALTON THOMPSON.

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  • THE STRUCTURE OF THE ATOMATOMIC MODELS

  • PIONEERS OF THE ATOMDEMOCRITUSLAVOISIERDALTONTHOMPSONMILLIKENRUTHERFORD

  • THE EARLY ATOMDEMOCRITUS IS THE MAN!!!YOU KNOW IT!ITS ALL GREEK TO ME...

  • DEMOCRITUSWAS 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 PARTICLESTHESE PARTICLES ARE INDIVISABLEHE CALLED THESE PARTICLES ATOMOS (MEANS INDIVISABLE)BUT HE HAD AN OPPONENT

  • ARISTOTLE = SCEPTICDEMOCRITUS ISANIGNORAMUS!ARISTOTLE WAS MUCH MORE POPULAR AND HE OPPOSED THE IDEA OF ATOMS!

  • ARISTOTLE = SCEPTICDEMOCRITUS ISANIGNORAMUS!ARISTOTLE BELIEVED THAT MATTER WAS CONTINUOUS.

  • DEMOCRITUS ATOMS

  • SO...CHEMISTRY DIED FOR ABOUT 1400 YEARSUNTIL...

  • SO...CHEMISTRY DIED FOR ABOUT 1400 YEARSIN THE1700S

  • FOUNDATIONS OF ATOMIC THEORYTHE PREDOMINATE BELIEF BY THE MID 1700S WAS THE MODERN DEFINITION OF AN ELEMENT AS A SUBSTANCE THAT CANNOT BE BROKEN DOWN BY ORDINARY CHEMICAL MEANSIT 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 THEORYHOWEVER, THERE WAS CONTROVERSY AS TO WHETHER ELEMENTS ALWAYS COMBINE IN THE SAME RATIO WHEN FORMING A PARTICULAR COMPOUND.IN THE 1790S, THE STUDY OF MATTER WAS REVOLUTIONIZED BY A NEW EMPHASIS ON THE QUANTITATIVE ANALYSISSCIENTISTS INVESTIGATIONS WERE MADE MORE ACCURATE BY NEW IMPROVED BALANCES

  • MATTER CAN BENEITHER CREATED NOR DESTROYED.ANTOINNE LAVOISIER TOOK ADVANTAGE HE BEGAN TO GATHER EVIDENCE ABOUT HOW MATTER BEHAVED BEFORE AND AFTER A REACTION.

  • MATTER CAN BENEITHER CREATED NOR DESTROYED.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

  • THE LAW OF DEFINITE PROPORTION

  • THE LAW OF MULTIPLE PROPORTIONS

  • IM BETTER LOOKING THAN PROUST!

  • +=COCOCARBON MONOXIDE+=COCOCARBON MONOXIDE+=COCO2CARBON DIOXIDE+O

    LAW OF DEFINITE PROPOR-TIONSA CHEM COMPD IS ALWAYS COMPOSED OF THE SAME ELEM. IN THE SAME PROPOR. BY MASS

    LAW OF MULTIPLE PROPOR-TIONSIF 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

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

  • ALL MATTER IS COMPOSED OF EXTREMELY SMALL PARTICLES CALLED ATOMSATOMS OF A GIVEN ELEMENT ARE IDENTICAL IN SIZE, MASS, AND OTHER PROPERTIES; ATOMS OF DIFFERENT ELEMENTS DIFFER IN SIZE, MASS, & OTHER PROPERTIES

  • ++

    ATOMS CANNOT BE SUBDIVIDED, CREATED, OR DESTROYEDATOMS OF DIFFERENT ELEMENTS COMBINE IN SIMPLE WHOLE # RATIOS TO FORM CHEM COMPDSIN CHEMICAL RXNS, ATOMS ARE COMBINED, SEPARATED, OR REARRANGED

  • DALTON AND HIS CONTEMPORARIESTHE EARLIEST THEORISTS THOUGHT THE ATOM WAS HARD AND ROUND, MUCH LIKE TINY MARBLES OR BALL BEARINGS.

  • STRUCTURE OF THE ATOMALTHOUGH DALTON THOUGHT ATOMS WERE INDIVISIBLE, INVESTIGATORS IN THE LATE 1800S PROVED OTHERWISEIT SOON BECAME CLEAR THAT ATOMS ARE ACTUALLY COMPOSED OF SEVERAL BASIC TYPES OF SMALLER PARTICLESAND ITS THE NUMBERS AND ARRANGEMENTS OF THESE SUB-ATOMIC PARTICLES THAT DETERMINES THE IDENTITY OF THE ATOM.

  • STRUCTURE OF THE ATOMTHE FIRST DISCOVERY OF A SUBATOMIC PARTICLE RESULTED FROM THE INVESTIGATIONS INTO THE RELATIONSHIP BETWEEN ELECTRICITY AND MATTER.IN THE LATE 1800S, MANY EXPERIMENTS WERE PERFORMED IN WHICH ELECTRIC CURRENT WAS PASSED THROUGH VARIOUS GASES AT LOW PRESSCARRIED OUT IN TUBES CALLED CATHODE-RAY TUBES

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

  • STRUCTURE OF THE ATOMTHEY HYPOTHESIZED THAT THE GLOW WAS CAUSED BY A STREAM OF PARTICLESTHEY CALLED THE STREAM A CATHODE RAY

  • STRUCTURE OF THE ATOMTHE 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. THOMPSONI PLAY WITHELECTRONS

  • J. J. THOMPSONTHOMPSONS INVESTIGATIONS SUPPLIED EVIDENCE THAT THE CATHODE RAY COULD BE DEFLECTED BY APPLYING A POSITIVELY CHARGED ELECTRIC FIELDTHIS HELPED THOMPSON DISC- OVER THAT THE CATHODE RAY WAS NEGATIVELY CHARGED.

  • THOMPSON WAS ABLE TO MEASURE THE RATIO OF THE CHARGE OF CATHODE RAY PARTICLES TO THEIR MASSHE FOUND THAT THE RATIO WAS THE SAME REGARDLESS OF THE METAL USED AS THE CATHODETHOMPSON CONCLUDED THAT ALL CATHODE RAYS ARE COMPOSED OF IDENTICAL NEGATIVELY CHARGED PARTICLESWHICH WERE LATER CALLED ELECTRONS

  • HE PROPOSED THAT THE ATOM LOOKS SOMETHING LIKE A CHOCOLATE CHIP COOKIETHOMPSONS ATOMIC MODELTHE COOKIE PART IS POS. MATTER TO CANCEL OUT THE NEG. ELECTRONSTHE CHIPS WOULD BEHIS ELECTRONS

  • THOMPSONS EXPERIMENTS REVEALED THAT THE ELECTRON HAS A VERY LARGE CHARGE IN RELATION TO ITS MASSIN 1909, ROBERT MILLIKAN, PERFORMED AN INGENIOUS EXPERIMENT TO CALCULATE THE MASS OF AN ELECTRONHE DISCOVERED THAT THE MASS OF THE ELECTRON IS ABOUT 1/2000TH THE MASS OF THE SIMPLEST ATOM (HYDRO.)

  • HELLO, MILLIKANDATS RIGHT!I SAVED THEDAY!

  • HIS OIL DROP EXPERIMENT SHOWED THAT EVEN THOUGH THE ATOMS OF DIFFERENT ELEMENTS ARE VERY DIFFERENT, THEIR ELECTRONS ARE IDENTICAL.AN ELECTRON IS AN ELECTRONTHE DIFFERENCE BETWEEN TWO DIFFERENT ATOMS IS THEIR NUMBER OF ELECTRONS NOT THEIR TYPE OF ELECTRON.HE ALSO CALCULATED THAT THE ELECTRONS MASS IS 9.109x10-31kg

  • SO FAR WEVE LEARNEDTHOMPSONS & MILLIKANS IDEAS:ATOMS ARE IN FACT DIVISABLEELECTRONS ARE PRESENT IN ATOMS OF ALL ELEM.ONE OF THE ATOMS FUNDMNTL PARTICLES IS NEG. CHARGEDATOMS 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 DISCOVERIESIN 1886, WHEN E. GOLDSTEIN OBSERVED A CATHODE-RAY TUBE AND FOUND RAYS TRAVELLING IN THE OPPOSITE DIRECTION OF THAT OF THE CATHODE RAYSHE CALLED THE RAYS CANAL RAYS AND CONCLUDED THAT THEY WERE COMPOSED OF POS. PARTICLESIT 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 CHARGEHAS A MASS NEARLY EQUAL TO THAT OF THE PROTONTHEREFORE THE SUBATOMIC PARTICLES ARE THE ELECTRON, PROTON, AND NEUTRON.OTHER SIGNIFICANT DISCOVERIES

  • electrone--109.11x10-28protonp++111.67x10-24neutronn0011.67x10-24

  • 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 NUCLEUS

  • ERNEST RUTHERFORDHOW IS THE ATOM BUILT?IN 1911, RUTHERFORD PERFORMED ONE OF THE MOST BRILLIANT INVESTIGATIONS EVER CONCIEVED.

  • RUTHERFORDS FAMOUS EXPERIMENTRUTHERFORD SET OUT TO TEST THE THOMPSON MODEL OF THE ATOMTHE TEST USED RELATIVELY MASSIVE RADIOACTIVE ALPHA PARTICLESALPHA 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.

  • WHAT HAPPENED?THE MAJORITY OF THE PARTICLES PASSED STRAIGHT THROUGH THE GOLD ATOMS, WITHOUT ANY DEFLECTIONEVEN MORE SURPRISINGLY, A SMALL FRACTION OF THE PARTICLES BOUNCED OFF THE GOLD FOIL ATOMS AT VERY LARGE ANGLESSOME 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 SPACETHIS EXPLAINED THE LACK OF DEFLECTION OF SOME OF THE PARTICLESHE CONCLUDED THAT ALL THE POSITIVE CHARGE AND ALMOST ALL THE MASS IS CONCENTRATED IN A SMALL COREHE CALLED THIS REGION THE NUCLEUS

  • A LITTLE REVIEW!THERE ARE THREE FUNDAMENTAL PARTICLES THAT TOGETHER MAKE UP THE ATOM.COMPOSED OF ELECTRONS, PROTONS, AND NEUTRONSTHE PROTONS AND THE NEUTRONS MAKE UP THE CENTER OF THE ATOMCENTER OF THE ATOM IS CALLED THE NUCLEUSTHE PROTONS & NEUTRONS OCC-UPY THE MASS OF THE ATOM

  • THE ELECTRONS SURROUND THE NUCLEUS AND OCCUPY MOST OF THE ATOMS VOLUMEHOW, THEN, ARE ATOMS OF HYDROGEN DIFFERENT FROM THOSE OF OXYGEN?A SUBATOMIC PARTICLES FROM ONE TYPE OF ATOM LOOKS LIKE PARTICLES FROM OTHER ATOMS

  • ITS THE NUMBERS OF PROTONS IN AN ATOM THAT MAKES ATOMS DIFFERENT.AN OXYGEN ATOM HAS 8 PROTONS IN ITS NUCLEUSA HYDROGEN ATOM HAS 1 PROTON IN ITS NUCLEUSTHE ATOMIC NUMBER OF AN ELEMENT IS THE NUMBER OF PROTONS IN THE NUCLEUS OF AN ATOM OF THAT ELEMENTSINCE OXYGENS NUCLEUS HAS 8 PROTONS ITS ATOMIC # IS 8THE PROTONS IDENTIFY THE TYPE OF ATOM, THE ONLY ATOM WITH 8 PROTONS IS OXYGEN

  • ATOMS OF THE 1ST TEN ATOMS

    HydrogenH11011HeliumHe22242LithiumLi33473BerylliumBe44594BoronB556115CarbonC666126NitrogenN777147OxygenO888168FluorineF9910199NeonNe1010102010

  • FOR EACH ELEMENT LISTED, THE NUMBER OF PROTONS EQUALS THE NUMBER OF ELECTRONSREMEMBER ATOMS ARE ELECTRICALLY NEUTRALIN AN ATOM, THE NUMBER OF ELECTRONS MUST EQUAL THE NUMBER OF PROTONSA HYDROGEN ATOM HAS 1 ELECTRNAN OXYGEN ATOM HAS 8 ELECTRNSTHE 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 NUMBERA CARBON ATOM, WHICH HAS 6 PROTONS AND 6 NEUTRONS, HAS A MASS NUMBER OF 12IF YOU KNOW THE ATOMIC NUMBER AND MASS NUMBER OF AN ATOM OF ANY ELEMENT, YOU CAN DETERMINE THE ATOMS COMPOSITIONTHE COMPOSITION OF ANY ATOM CAN BE REPRESENTED IN SHORTHAND NOTATION:

  • CHEMICAL COMPOSITION SHORTHANDCl3517MASS NUMBERATOMIC NUMBERNUMBER OF PROTONS# OF PROTONS+# 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.ISOTOPES

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

    protonneutronelectronBERYLLIUMISOTOPES

  • EXAMPLE OF AN ISOTOPE

  • IONSAN ELEMENTS 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 CHARGEAN ION THAT HAS FEWER ELECTRONS THAN PROTONS HAS A POSITIVE ELECTRICAL CHARGENOTE: ITS THE PROTONS THAT DEFINE THE TYPE OF ATOM IT IS, BUT THE ELECTRONS DEFINE THE ATOMS CHARGE.

  • SOME ATOMS GAIN ELECTRONSO--------O-2----------ATOMS IONIC CHARGE = # PROTONS - # ELECTRONS

  • ATOMS, IONS, AND ISOTOPESATOMSNEUTRAL AND ARE DEFINED BY THE # OF PROTONS IN THEIR NUCLEUS3 p+ = Li ATOM, ETC.IONSHAVE AN ELECTRICAL CHARGE DETERMINED BY # PROTONS - # ELECTRONSN-2 = 7 p+ - 9 e- ; ETC.ISOTOPESTWO ATOMS WITH THE SAME # OF PROTONS, BUT DIFFERENT #S OF NEUTRONS OR MASSESCALCIUM-40 & CALCIUM-44

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