Transcript atomic structure - Mr. Damiano`s Class

CHAPTER 3
THE STRUCTURE OF MATTER
CHAPTER 3
LABORATORY CHEMISTRY
1
ATOMIC STRUCTURE
1.
 2.
 3.
 4.

EARLY MODELS OF THE ATOM
DISCOVERING ATOMIC STRUCTURE
MODERN ATOMIC THEORY
CHANGES IN THE NUCLEUS
CHAPTER 3
LABORATORY CHEMISTRY
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EARLY MODELS OF THE ATOM

DEMOCRITUS: (450 BC)
– “ATOMOS”


DEMOCRITUS
THE SMALLEST PARTICLE OF AN ELEMENT
THAT RETAINS THE CHEMICAL IDENTITY OF
THAT ELEMENT.
ARISTOTLE:
– EARTH, AIR, FIRE, AND WATER
CHAPTER 3
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EARLY MODELS OF THE ATOM



LAVOISIER, ANTON: (LATE 1700’S)
– LAW OF CONSERVATION OF MATTER (AND
ENERGY)
PROUST, JOSEPH: (1799)
– LAW OF CONSTANT COMPOSITION
DALTON, JOHN (1803)
– SCHOOL TEACHER
– ATOMIC THEORY OF MATTER
CHAPTER 3
LABORATORY CHEMISTRY
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EARLY MODELS OF THE ATOM

DALTON’S ATOMIC THEORY
– EACH ELMENT IS COMPOSED OF EXTREMELY
SMALL PARTICLES CALLED ATOMS.
– ALL ATOMS OF A GIVEN ELEMENT ARE
IDENTICAL, BUT THEY DIFFER FROM THOSE OF
ANY OTHER ELEMENT.
– ATOMS ARE NEITHER CREATED NOR DESTROYED
IN ANY CHEMICAL REACTION.
– A GIVEN COMPOUND ALWAYS HAS THE SAME
RELATIVE NUMBERS AND KINDS OF ATOMS.
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EARLY MODELS OF THE ATOM

WHY IS THERE SUCH DIVERSITY IN NATURE
IF THERE ARE ONLY ABOUT 100 DIFFERENT
KINDS OF ATOMS ?
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DISCOVERING ATOMIC
STRUCTURE


FARADAY, MICHAEL (1839)
– SUGGESTED THAT THE STRUCTURE OF
ATOMS WAS RELATED TO ELECTRICITY.
FRANKLIN, BENJAMIN (MID-1700’S)
– STATIC ELECTRICITY
– BATTERIES
– “POSITIVE AND NEGATIVE CHARGES”
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DISCOVERING ATOMIC
STRUCTURE

CATHODE RAY TUBE
– INVENTED IN THE MID-1800’S
ELECTRON BEAM
ANODE
+
CATHODE
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DISCOVERING ATOMIC
STRUCTURE
– THOMSON, J.J. (1896)



CHAPTER 3
DISCOVERED AND NAMED ELECTRONS
DETERMINED THE CHARGE (1.76 X 108
COULOMBS/GRAM)
“PLUM-PUDDING” MODEL OF THE ATOM
LABORATORY CHEMISTRY
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DISCOVERING ATOMIC
STRUCTURE
– RUTHERFORD, ERNEST (EARLY 1900’S)

ALPHA(2+) AND BETA(1-) RADIATION (GAMMA
RADIATION WAS DISCOVERED LATER)
– MADE OF PARTICLES
CHAPTER 3
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RUTHERFORD’S GOLD FOIL
EXPERIMENT
GOLD
FOIL
CHAPTER 3
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Niels Bohr !
DISCOVERING Hi..I’m
ATOMIC
And I love Physics !
STRUCTURE

Well…I’m Ernie
Rutherford ! And I
love a good Cigar!
THE NUCLEAR ATOM
– ALPHA SCATTERING EXPERIMENT (GOLD
FOIL EXPERIMENT)
– RUTHERFORD NAMES THE NUCLEUS AND
DETERMINES ITS CHARGE
– THE RUTHERFORD/BOHR MODEL OF THE
ATOM
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MODERN ATOMIC THEORY

THE STRUCTURE OF THE ATOM
– NUCLEUS


PROTONS
NEUTRONS
– ELECTRONS
– RUTHERFORD’S VISUALIZATION
(MINATURE SOLAR SYSTEM)
– UNCERTAINTY (ELECTRON CLOUD)
CHAPTER 3
LABORATORY CHEMISTRY
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“PLUMBPUDDING”
MODEL
“SOLAR
SYSTEM”
MODEL
CHAPTER 3
LABORATORY CHEMISTRY
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DISCOVERING ATOMIC
STRUCTURE
PARTICLE
LOCATION CHARGE
MASS
(GRAMS)
MASS
(AMU)
PROTON
INSIDE
NUCLEUS
+1.602 X 10-19
1.673 X 10-24
1.0073 = 1
NEUTRON
INSIDE
NUCLEUS
0
1.675 X 10-24
1.0087 = 1
ELECTRON
OUTSIDE
NUCLEUS
-1.602 X 10-19
9.109
10-29-28
9.109 XX 10
0.0006 = 0
1.63 X 10-24
NOTE THAT EVEN THOUGH THE MASS OF AN ELECTRON
IS FAR LESS THAN A PROTON….THE CHARGES ARE OF
THE SAME MAGNITUDE BUT OPPOSITE
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DISCOVERING ATOMIC
STRUCTURE

ATOMIC NUMBERS
– MOSELEY, HENRY (1887-1915)



CHAPTER 3
STUDENT OF RUTHERFORD
DISCOVERED THE PROTON (UNIQUE POSITIVE
CHARGE OF THE NUCLEUS)
ATOMIC NUMBER = NUMBER OF PROTONS IN
THE NUCLEUS AND ALSO = THE NUMBER OF
ELECTRONS AROUND THE NUCLEUS
LABORATORY CHEMISTRY
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DISCOVERING ATOMIC
STRUCTURE

PERIODIC TABLE
ATOMIC
NUMBER
ATOMIC
MASS
CHAPTER 3
N
14.0067
7
NITROGEN
LABORATORY CHEMISTRY
Atomic
Symbol
Element
Name
17
DISCOVERING ATOMIC
STRUCTURE

WRITING THE ELEMENTS TO
CALCULATE PROTONS, NEUTRONS,
AND ELECTRONS
– TO CALCULATE THE NUMBER OF
NEUTRONS, SUBTRACT THE NUMBER OF
PROTONS FROM THE ATOMIC MASS
– THE NUMBER OF ELECTRONS = THE
NUMBER OF PROTONS (ATOMIC NUMBER)
IN A NEUTRAL ATOM
CHAPTER 3
LABORATORY CHEMISTRY
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DISCOVERING ATOMIC
STRUCTURE
ATOMIC MASS
“” IN AMU
ATOMIC NUMBER
“Z” NUMBER
NUMBER OF
NEUTRONS
CHAPTER 3
23
11
12
Na
LABORATORY CHEMISTRY
THIS IS ALSO THE NUMBER OF
ELECTRONS IN A GROUND STATE
ATOM!!!!!
19
DISCOVERING ATOMIC
STRUCTURE

IONS
– WHEN AN ATOM GAINS OR LOSES AN ELECTRON
IT ACQUIRES AN ELECTRICAL CHARGE
– PLACE THE APPROPRIATE CHARGE SIGN AND
NUMBER AT THE UPPER RIGHT OF THE ELEMENT
SYMBOL
CHARGE OF AN ION = NUMBER OF PROTONS-NUMBER OF ELECTRONS
N3+ O2- Fe2+ Cl2- Ca2+
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PRACTICE
LOSES 3 ELECTRONS
14
7
N
14
7
GROUND STATE ATOM
NEUTRAL (NO CHARGE)
(+7) + (-7) = 0
THE NUMBER OF
PROTONS DO NOT
CHANGE
N
+3
AN ION
A CHARGED ATOM
(+7)+( -4) = 3 +
CHARGE
ELECTRONS
PROTONS
PROTONS
ELECTRONS
CHARGE
CHAPTER 3
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DISCOVERING ATOMIC
STRUCTURE

ISOTOPES
– ATOMS THAT HAVE THE SAME NUMBER
OF PROTONS BUT DIFFERENT
NUMBERS OF NEUTRONS
(OVERWEIGHT OR UNDERWEIGHT
ATOMS)
– NAMED BY THE ISOTOPES MASS
NUMBER (PROTONS + NEUTRONS)
CHAPTER 3
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DISCOVERING ATOMIC
STRUCTURE
12
6
C
14
6
GROUND STATE
CARBON
RADIOACTIVE
CARBON
CARBON-12
CHAPTER 3
C
CARBON-14
LABORATORY CHEMISTRY
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DISCOVERING ATOMIC
STRUCTURE

THE MASS OF AN ATOM
– ATOMIC MASS UNITS (AMU)
– AVERAGE MASS OF AN ELEMENT’S ATOMS
IS CALLED THE ATOMIC MASS.
CHAPTER 3
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CHANGES IN THE NUCLEUS
NUCLEAR REACTIONS CHANGE THE
COMPOSITION OF AN ATOM’S
NUCLEUS.
 NUCLEAR STABILITY

– STABLE NUCLEUS (NOT RADIOACTIVE)

RADIOACTIVE DECAY
– RADIATION (ALPHA, BETA, AND GAMMA)
CHAPTER 3
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CHANGES IN THE NUCLEUS

TYPES OF RADIATION
NAME
IDENTITY
CHARGE
Alpha ()
Helium-4
nuclei
2+
Beta ()
electrons
1-
Gamma ()
High energy
non-particle
radiation
none
CHAPTER 3
LABORATORY CHEMISTRY
PENETRATING
ABILITY
Low, stopped
by paper
Medium,
stopped by
heavy clothing
High, stopped
by lead
26
ALPHA-BETA-GAMMA
SCATTERING
CHAPTER 3
LABORATORY CHEMISTRY
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CHANGES IN THE NUCLEUS

Alpha decay
226
88
CHAPTER 3
Ra  Rn  
222
86
LABORATORY CHEMISTRY
4
2
28
CHANGES IN THE NUCLEUS
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 the
nucleus 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.
CHAPTER 3
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CHANGES IN THE NUCLEUS

Beta decay
I 
131
53
CHAPTER 3
131
54
Xe 
LABORATORY CHEMISTRY

0
1
30
CHANGES IN THE NUCLEUS

Gamma decay
U 
235
92
CHAPTER 3
U  
235
92
LABORATORY CHEMISTRY
0
0
31
CHANGES IN THE NUCLEUS
WHAT CHANGES ACCOMPANY A
NUCLEAR REACTION?
 DEFINE RADIOACTIVITY.
 IS ALL RADIOACTIVITY COMPOSED OF
PARTICLES ?
 DESCRIBE THE FORCE THAT HOLDS
THE NUCLEUS TOGETHER.

CHAPTER 3
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