http://www.cubicao.tk/nature/energymatter.html

PIONEERS OF THE ATOMPIONEERS OF THE ATOM

DEMOCRITUSLAVOISIERDALTONTHOMPSONMILLIKENRUTHERFORDBOHR

DEMOCRITUSLAVOISIERDALTONTHOMPSONMILLIKENRUTHERFORDBOHR

THE EARLY ATOMTHE EARLY ATOM

DEMOCRITUS IS THE MAN !

DEMOCRITUS IS THE MAN !

It’s all Greek to me ……

DEMOCRITUSDEMOCRITUSWAS A GREEK PHILOSOPHER THAT BEGAN

WONDERING WHAT WAS THE UNIVERSE MADE OF.

HE PROPOSED THAT ALL THE MATTER IN THE UNIVERSE IS COMPOSED OF ‘TINY PARTICLES’.

THESE PARTICLES ARE ‘INDIVISIBLE’.

HE CALLED THESE PARTICLES ‘ATOMOS’ (MEANING ‘INDIVISIBLE’).

BUT HE HAD AN OPPONENT……

WAS A GREEK PHILOSOPHER THAT BEGAN WONDERING WHAT WAS THE UNIVERSE MADE OF.

HE PROPOSED THAT ALL THE MATTER IN THE UNIVERSE IS COMPOSED OF ‘TINY PARTICLES’.

THESE PARTICLES ARE ‘INDIVISIBLE’.

HE CALLED THESE PARTICLES ‘ATOMOS’ (MEANING ‘INDIVISIBLE’).

BUT HE HAD AN OPPONENT……

ARISTOTLE = SKEPTICARISTOTLE = SKEPTIC

Democritus is Democritus is an ignoramus!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 = SKEPTICARISTOTLE = SKEPTIC

ARISTOTLE BELIEVED THAT MATTER WAS

‘CONTINUOUS’.

ARISTOTLE BELIEVED THAT MATTER WAS

‘CONTINUOUS’.

Democritus is Democritus is an ignoramus!an ignoramus!

ARISTOTLE’S FOUR BASIC ELEMENTSEARTH, AIR, FIRE and WATER

ARISTOTLE’S FOUR BASIC ELEMENTSEARTH, AIR, FIRE and WATER

DEMOCRITUS’ ATOMS

DEMOCRITUS’ ATOMS

BECAUSE OF ARISTOTLE’S GREAT INFLUENCE……

BECAUSE OF ARISTOTLE’S GREAT INFLUENCE……

...’ATOMS’ DIED FOR ABOUT 1,400 YEARS...’ATOMS’ DIED FOR ABOUT 1,400 YEARS

UNTIL...UNTIL...

IN THE1700’S…

IN THE1700’S…

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 PHYSICAL AND CHEMICAL

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 PHYSICAL AND CHEMICAL

PROPERTIES THAN THOSE OF THE ELEMENTS THAT FORM THEM.

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 MASS 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 MASS BALANCES.

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.

ANTOINE LAVOISIERANTOINE LAVOISIER

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 Matter can be neither created neither created nor destroyed!nor destroyed!

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’.

Matter can be Matter can be neither created neither created nor destroyed!nor destroyed!

JOHN DALTON INVESTIGATED TWO OTHER FUNDAMENTAL

IDEAS

JOHN DALTON INVESTIGATED TWO OTHER FUNDAMENTAL

IDEAS

The Law The Law of of

Definite Definite ProportioProportio

nn

The Law The Law of of

Multiple Multiple ProportioProportio

nsns

LAW OF LAW OF DEFINITE DEFINITE PROPOR-PROPOR-

TIONSTIONS

A CHEMICAL COMPOUND IS ALWAYS A CHEMICAL COMPOUND IS ALWAYS COMPOSED OF THE SAME ELEMENTS IN COMPOSED OF THE SAME ELEMENTS IN

THE SAME PROPORTION BY MASS.THE SAME PROPORTION BY MASS.

LAW OF LAW OF MULTIPLE MULTIPLE PROPOR-PROPOR-

TIONSTIONS

IF TWO DIFFERENT COMPOUNDS ARE IF TWO DIFFERENT COMPOUNDS ARE COMPOSED OF THE SAME TWO COMPOSED OF THE SAME TWO

ELEMENTS, THEN THE RATIO OF OF THE ELEMENTS, THEN THE RATIO OF OF THE ELEMENTS IS ALWAYS A RATIO OF SMALL ELEMENTS IS ALWAYS A RATIO OF SMALL

WHOLE NUMBERS.WHOLE NUMBERS.

++++ ====CC OO COCO

++++ ====CC OO COCO

CARBON CARBON MONOXIDEMONOXIDECARBON CARBON

MONOXIDEMONOXIDE

++++ ====CC OO COCO22

CARBON CARBON DIOXIDEDIOXIDECARBON CARBON DIOXIDEDIOXIDE

++++OO

CARBON CARBON MONOXIDEMONOXIDECARBON CARBON

MONOXIDEMONOXIDE

IN 1808, JOHN DALTON PROPOSED AN EXPLANATION FOR THE LAW OF THE

CONSERVATION OF MASS AND ‘DEFINITE PROPORTIONS.

HE ALSO FORMULATED THE LAW OF ‘MULTIPLE PROPORTIONS’.

HE REASONED THAT ELEMENTS WERE COMPOSED OF ‘ATOMS’ AND THAT ONLY

WHOLE NUMBERS OF ATOMS CAN COMBINE TO FORM COMPOUNDS

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 THE

CONSERVATION OF MASS AND ‘DEFINITE PROPORTIONS.

HE ALSO FORMULATED THE LAW OF ‘MULTIPLE PROPORTIONS’.

HE REASONED THAT ELEMENTS WERE COMPOSED OF ‘ATOMS’ AND THAT ONLY

WHOLE NUMBERS OF ATOMS CAN COMBINE TO FORM COMPOUNDS

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 IDENTICAL ELEMENT ARE IDENTICAL IN SIZE, MASS, AND IN SIZE, MASS, 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, CREATED, SUBDIVIDED, CREATED, OR DESTROYED.OR DESTROYED.

4.4.ATOMS OF DIFFERENT ATOMS OF DIFFERENT ELEMENTS COMBINE IN ELEMENTS COMBINE IN SIMPLE WHOLE SIMPLE WHOLE NUMBER RATIOS TO NUMBER RATIOS TO FORM CHEMICAL FORM CHEMICAL COMPOUNDS.COMPOUNDS.

5.5.IN CHEMICAL IN CHEMICAL REACTIONS, ATOMS ARE REACTIONS, ATOMS ARE COMBINED, COMBINED, SEPARATED, OR SEPARATED, OR REARRANGED.REARRANGED.

++++ ++++

DALTON AND HIS CONTEMPORARIESDALTON AND HIS

CONTEMPORARIES

THE EARLIEST THEORISTS THOUGHT THE ATOM WAS

HARD AND ROUND, MUCH LIKE TINY

MARBLES OR BALL BEARINGS.

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.

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 PRESSURE.

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 PRESSURE.

CARRIED OUT IN TUBES CALLED

CATHODE-RAY TUBES

J.J. THOMPSON Around J.J. THOMPSON Around 19001900

J.J. THOMPSON Around J.J. THOMPSON Around 19001900

THOMPSON NOTICED THAT WHEN CURRENT WAS PASSED THROUGH A CATHODE RAY TUBE, THE SURFACE OF THE TUBE DIRECTLY OPPOSITE

THE CATHODE GLOWED.

THOMPSON NOTICED THAT WHEN CURRENT WAS PASSED THROUGH A CATHODE RAY TUBE, THE SURFACE OF THE TUBE DIRECTLY OPPOSITE

THE CATHODE GLOWED.

THOMPSON THEORIZED THAT THE GLOW WAS CAUSED BY A STREAM

OF ‘PARTICLES’.HE CALLED THIS STREAM A

‘CATHODE RAY’.

THOMPSON THEORIZED THAT THE GLOW WAS CAUSED BY A STREAM

OF ‘PARTICLES’.HE CALLED THIS STREAM A

‘CATHODE RAY’.

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

THOMPSON’S INVESTIGATIONS GAVE EVIDENCE THAT THE CATHODE RAY COULD BE DEFLECTED BY APPLYING A POSITIVELY

CHARGED ELECTRIC FIELD.

THIS HELPED THOMPSON DISCOVER THAT THE CATHODE RAY WAS

‘NEGATIVELY CHARGED’.

THOMPSON’S INVESTIGATIONS GAVE EVIDENCE THAT THE CATHODE RAY COULD BE DEFLECTED BY APPLYING A POSITIVELY

CHARGED ELECTRIC FIELD.

THIS HELPED THOMPSON DISCOVER THAT THE CATHODE RAY WAS

‘NEGATIVELY CHARGED’.

++

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.

THE COOKIE PART IS POSITIVE MATTER, TO CANCEL OUT THE

NEGATIVE ELECTRONS.

THE COOKIE PART IS POSITIVE MATTER, TO CANCEL OUT THE

NEGATIVE ELECTRONS.

THE CHIPS WOULD BEHIS ‘ELECTRONS’.

THE CHIPS WOULD BEHIS ‘ELECTRONS’.

THOMPSON WAS THOMPSON WAS ‘ENGLISH’……… HE CALLED HIS ‘ENGLISH’……… HE CALLED HIS

MODEL THE MODEL THE ‘PLUM PUDDING ‘PLUM PUDDING ATOM’ATOM’

THOMPSON WAS THOMPSON WAS ‘ENGLISH’……… HE CALLED HIS ‘ENGLISH’……… HE CALLED HIS

MODEL THE MODEL THE ‘PLUM PUDDING ‘PLUM PUDDING ATOM’ATOM’

IN 1909, ROBERT MILLIKAN, PERFORMED AN 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……HYDROGEN.

IN 1909, ROBERT MILLIKAN, PERFORMED AN 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……HYDROGEN.

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 THE 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 THE TYPE OF ELECTRON.

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

THOMPSON’S & MILLIKAN’S IDEAS

ATOMS ARE IN FACT DIVISIBLE.

ELECTRONS ARE PRESENT IN ATOMS OF ALL ELEMENTS.

ONE OF THE ATOM’S FUNDAMENTAL PARTICLES IS NEGATIVE 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 DIVISIBLE.

ELECTRONS ARE PRESENT IN ATOMS OF ALL ELEMENTS.

ONE OF THE ATOM’S FUNDAMENTAL PARTICLES IS NEGATIVE 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.

BUT, NO ONE KNEW WHAT THE BUT, NO ONE KNEW WHAT THE INSIDE OF AN ‘ATOM’ WAS INSIDE OF AN ‘ATOM’ WAS

REALLY LIKE UNTIL……REALLY LIKE UNTIL……

ERNEST RUTHERFORD

ERNEST RUTHERFORD

IN 1911, RUTHERFORD PERFORMED ONE OF THE MOST BRILLIANT EXPERIMENTS EVER.

IN 1911, RUTHERFORD PERFORMED ONE OF THE MOST BRILLIANT EXPERIMENTS EVER.

What’s What’s inside an inside an

atom?atom?

IN THE EXPERIMENT, RUTHERFORD SHOT A NARROW BEAM OF ALPHA PARTICLES AT A

VERY THIN SHEET OF GOLD FOIL.

IF ATOMS WERE LIKE ‘PLUM PUDDING’, THE ALPHA PARTICLES SHOULD HAVE PASSED EASILY THROUGH THE GOLD, WITH ONLY A SLIGHT DEFLECTION.

IN THE EXPERIMENT, RUTHERFORD SHOT A NARROW BEAM OF ALPHA PARTICLES AT A

VERY THIN SHEET OF GOLD FOIL.

IF ATOMS WERE LIKE ‘PLUM PUDDING’, THE ALPHA PARTICLES SHOULD HAVE PASSED EASILY THROUGH THE GOLD, WITH ONLY A SLIGHT DEFLECTION.

BUT, THAT IS NOT WHAT BUT, THAT IS NOT WHAT HAPPENED……HAPPENED……

WHAT HAPPENED?WHAT HAPPENED?THE MAJORITY OF THE PARTICLES PASSED

‘STRAIGHT THROUGH’ THE GOLD ATOMS.

MORE SURPRISINGLY, A SMALL NUMBER OF THE PARTICLES ‘BOUNCED OFF’ THE GOLD FOIL AT VERY LARGE ANGLES.

AND SOME EVEN BOUNCED BACK DIRECTLY AT THE SOURCE!

THE MAJORITY OF THE PARTICLES PASSED ‘STRAIGHT THROUGH’ THE GOLD ATOMS.

MORE SURPRISINGLY, A SMALL NUMBER OF THE PARTICLES ‘BOUNCED OFF’ THE GOLD FOIL AT VERY LARGE ANGLES.

AND SOME EVEN BOUNCED BACK DIRECTLY AT THE SOURCE!

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

HE PROPOSED THAT THE ATOM IS MOSTLY EMPTY SPACE.

HE CONCLUDED THAT ALL THE POSITIVE CHARGE AND ALMOST ALL THE MASS IS

CONCENTRATED IN A SMALL CORECALLED THE ‘NUCLEUS’.

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

HE PROPOSED THAT THE ATOM IS MOSTLY EMPTY SPACE.

HE CONCLUDED THAT ALL THE POSITIVE CHARGE AND ALMOST ALL THE MASS IS

CONCENTRATED IN A SMALL CORECALLED THE ‘NUCLEUS’.

IN 1932, THE ENGLISH PHYSICIST JAMES CHADWICK CONFIRMED THE EXISTANCE OF

YET ANOTHER SUBATOMIC PARTICLE

THE NEUTRON.

A PARTICLE WITH NO CHARGE.

IT 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.

A PARTICLE WITH NO CHARGE.

IT HAS A MASS NEARLY EQUAL TO THAT OF THE PROTON.

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

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

A LITTLE REVIEWA LITTLE REVIEWTHERE ARE THREE FUNDAMENTAL

PARTICLES THAT MAKE UP THE ATOM.

THEY ARE ELECTRONS, PROTONS, AND NEUTRONS.

THE PROTONS AND THE NEUTRONS MAKE UP THE CENTER OF THE ATOM,

WHICH IS CALLED THE NUCLEUS.

THE PROTONS & NEUTRONS MAKE UP THE MASS OF THE ATOM.

THERE ARE THREE FUNDAMENTAL PARTICLES THAT MAKE UP THE

ATOM.

THEY ARE ELECTRONS, PROTONS, AND NEUTRONS.

THE PROTONS AND THE NEUTRONS MAKE UP THE CENTER OF THE ATOM,

WHICH IS CALLED THE NUCLEUS.

THE PROTONS & NEUTRONS MAKE UP 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 IT’S NUCLEUS.

A HYDROGEN ATOM HAS 1 PROTON IN IT’S 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 IT’S ATOMIC NUMBER 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 IT’S NUCLEUS.

A HYDROGEN ATOM HAS 1 PROTON IN IT’S 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 IT’S ATOMIC NUMBER IS 8.

THE PROTONS IDENTIFY THE TYPE OF ATOM, THE ONLY ATOM WITH 8 PROTONS IS

OXYGEN.

ATOMS OF THE FIRST TEN ELEMENTSATOMS OF THE FIRST TEN ELEMENTS

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 ELECTRON.

AN OXYGEN ATOM HAS 8 ELECTRONS.

THE MASS OF AN ATOM IS CONCENTRATED IN IT’S NUCLEUS AND DEPENDS ON THE NUMBER 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 ELECTRON.

AN OXYGEN ATOM HAS 8 ELECTRONS.

THE MASS OF AN ATOM IS CONCENTRATED IN IT’S NUCLEUS AND DEPENDS ON THE NUMBER 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 SHORTHANDCHEMICAL 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

BERYLLIUM ISOTOPESBERYLLIUM ISOTOPES

SODIUM ISOTOPESSODIUM ISOTOPES

EXAMPLE OF AN ISOTOPEEXAMPLE OF AN ISOTOPE

ClCl3535

1717 ClCl3737

1717

20 20 NEUTRONSNEUTRONS

ATOMIC MASS

ATOMIC NUMBER

1818 NEUTRONSNEUTRONS

IONSIONSAN 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.

‘‘LOST’LOST’ AN AN ELECTRON ELECTRON = + CHARGE= + CHARGE

‘‘LOST’LOST’ AN AN ELECTRON ELECTRON = + CHARGE= + CHARGE

‘‘GAINED’GAINED’ AN AN

ELECTRON ELECTRON = - CHARGE= - CHARGE

‘‘GAINED’GAINED’ AN AN

ELECTRON ELECTRON = - CHARGE= - CHARGE

SOME ATOMS GAIN ELECTRONS

SOME ATOMS GAIN ELECTRONS

O

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ATOM’S IONIC CHARGE = NUMBER OF PROTONS – NUMBER OF ELECTRONS

ATOM’S IONIC CHARGE = NUMBER OF PROTONS – NUMBER OF 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

How are How are electrons electrons arranged arranged inside aninside an

atom?atom?

NIELS BOHR INVESTGATED THE NIELS BOHR INVESTGATED THE ‘ARRANGEMENT’ OF ELECTRONS‘ARRANGEMENT’ OF ELECTRONSNIELS BOHR INVESTGATED THE NIELS BOHR INVESTGATED THE ‘ARRANGEMENT’ OF ELECTRONS‘ARRANGEMENT’ OF ELECTRONS

BOHR FOUND THAT ELECTRONS TRAVEL IN DISCRETE ‘ORBITS’

ABOUT THE NUCLEUS.

THE CHEMICAL PROPERTIES OF AN ATOM ARE DETERMINED BY THE NUMBER OF ELECTRONS IN

AN ATOM’S OUTER ORBIT.

BOHR FOUND THAT ELECTRONS TRAVEL IN DISCRETE ‘ORBITS’

ABOUT THE NUCLEUS.

THE CHEMICAL PROPERTIES OF AN ATOM ARE DETERMINED BY THE NUMBER OF ELECTRONS IN

AN ATOM’S OUTER ORBIT.

ELECTRON SHELLS AND ATOMIC ELECTRON SHELLS AND ATOMIC STRUCTURESTRUCTURE

ELECTRON SHELLS AND ATOMIC ELECTRON SHELLS AND ATOMIC STRUCTURESTRUCTURE

THE FIRST SHELL WILL HOLD UP TO 2 THE FIRST SHELL WILL HOLD UP TO 2 ELECTRONS.ELECTRONS.

THE SECOND AND THIRD SHELLS WILL THE SECOND AND THIRD SHELLS WILL HOLD UP TO 8 ELECTRONS.HOLD UP TO 8 ELECTRONS.

SOMETIMES SHELLS ARE MADE OF SOMETIMES SHELLS ARE MADE OF SUB-SHELLS.SUB-SHELLS.

ATOMS WITH ELECTRONS OUTSIDE OF ATOMS WITH ELECTRONS OUTSIDE OF FILLED SHELLS OR WITH MISSING FILLED SHELLS OR WITH MISSING

ELECTRONS ARE VERY CHEMICALLY ELECTRONS ARE VERY CHEMICALLY REACTIVE.REACTIVE.

THE FIRST SHELL WILL HOLD UP TO 2 THE FIRST SHELL WILL HOLD UP TO 2 ELECTRONS.ELECTRONS.

THE SECOND AND THIRD SHELLS WILL THE SECOND AND THIRD SHELLS WILL HOLD UP TO 8 ELECTRONS.HOLD UP TO 8 ELECTRONS.

SOMETIMES SHELLS ARE MADE OF SOMETIMES SHELLS ARE MADE OF SUB-SHELLS.SUB-SHELLS.

ATOMS WITH ELECTRONS OUTSIDE OF ATOMS WITH ELECTRONS OUTSIDE OF FILLED SHELLS OR WITH MISSING FILLED SHELLS OR WITH MISSING

ELECTRONS ARE VERY CHEMICALLY ELECTRONS ARE VERY CHEMICALLY REACTIVE.REACTIVE.

ATOMS WITH ‘FILLED’ SHELLS ARE ATOMS WITH ‘FILLED’ SHELLS ARE STABLE, OR NON-REACTIVE. STABLE, OR NON-REACTIVE. THESE THESE

ARE CALLED ‘INERT GASES’ARE CALLED ‘INERT GASES’

ATOMS WITH ‘FILLED’ SHELLS ARE ATOMS WITH ‘FILLED’ SHELLS ARE STABLE, OR NON-REACTIVE. STABLE, OR NON-REACTIVE. THESE THESE

ARE CALLED ‘INERT GASES’ARE CALLED ‘INERT GASES’