Download Structure of the atom,english2009-08

THE STRUCTURE OF THE ATOM
AND
THE PERIODIC SYSTEM
HEALTH CHEMISTRY
FOR CLASS X,SEMESTER 1
COMPETENTION STANDARD
FUNDAMENTAL COMPETENTION
The Competency standard
Identify the structure of the atom and characteristic
of unsur in periodic system.
Fundamental Competency
 Describe the development of the atomic theory
 Explain the periodic properties of elements
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LEARNING OBJECTIVES
After studying this chapter, students are
expected tobe able to:
 Define the atom
 explain the development of the atomic theory/ model
 Describe the structure of atom containing subatomic particles :
protons, neutrons, and electrons.
 Define atomic number (Z) and mass number (A)
 Define isotopes, isotones, and isobars
 Write down the electron configuration of atoms
 Explain the historical development of the periodic system
 Explain the periodic properties of elements
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THE STRUCTURE OF THE ATOM
Tiny particles of elements
ATOM
An element is matter composed of
identical atoms that have the same
mass and properties.
Tiny
particles
can be
divided
Different elements have different
masses and properties
Can be divided
Sub
atomic
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ATOM
Sub
atomic
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Sub
atomic
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THE ATOMIC THEORY
ATOMIC THEORY
DEMOCRITU
S
MODERN
DALTON
THOMSON
NIELS BOHR
RUTHERFOR
D
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DEMOCRITUS (460 -370 SM)
The tiny particles could not be divided
to any further estent are called
ATOMS
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DALTON’S ATOMIC THEORY
(1803-1807)
 Matter is made up of tiny particles called
atoms
 An element in matter composed of identical
atoms that have the same mass and
properties
 Different elements have different masses
and properties
 Atoms cannot be created nor destroyed.
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DALTON’S ATOMIC THEORY
(1803-1807)
 Chemical reactions are merely rearrangement of
atoms.
 A compound is composed of at least two atoms
from different elements with a fixed and spesific
propotion. Atoms in compound are combined
together through atomic bonding
one atom
of Oksigen
two
moleculs
of Oksigen
Hal.: 8
two
moleculs of
Hidrogen
two
molekuls
of water
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One atom
of
Hidrogen
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THOMSON’S ATOMIC MODEL
Atom is a sphere in which the positive charges spread out evenly in
the atom are neutralized by the negative charges positioned among
the positive charges. Electrons in an atom are like raisins in plum
pudding.
Atomic
model
Are like
Raisins in
Plum pudding
electron
Positive charges spread
out evenly in the atom
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THE DISCOVERY OF THE
SUBATOMIC PARTICLE : ELECTRON
Heinrich Geissler
Julius Plucker
Plucker used the Geissler tube for a
gas electrolysis experiment.He placed
a metal plate on each end of the
tube.Electrode that is connected to the
negative end is called cathode, while
the one connecte to the positive end is
called anode. He then charged both
the cathode and anode with high
voltage and observed beams of
current in the tube shown by rays
coming from the cathode.
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Pompa
hisap
Katode
--
Anode +
Gas
tekanan
rendah
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RUTHERFORD’S ATOMIC MODEL
 A large fraction of the room in an atom is
empty.
 Atom has a tiny yet very dense core called
the nucleus.
 The charge of the nucleus is the same as
that of the alfa particle, which is positive.
 Atom is composed of a positively charged
nucleus surrounded by negatively charged
electrons.
 Most of the mass in an atom is consentrated
in the nucleus.
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RUTHERFORD’S EXPERIMENT
A beam of alfa particles is directed towards
the thin gold plate through alfa slit in the
lead plate.
Alpha particles that pass the empty space
Go straight through.
Alpha particles that approach
the nucleus are deflected.
Alpha particles that hit the
nucleus are bounced back
electron
nucleon
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NIELS BOHR’S ATOMIC MODEL AND
MODERN’S ATOMIC MODEL

Niels Bohr succeeded in overcoming the weakness
of the Rutherford’s atomic model.
Model atom menurut Niels Bohr, 1913:

Dalam atom terdapat lintasan-lintasan tempat
elektron

Elektron yang boleh berada pada lintasan yang
diperbolehkan,tidak boleh di antara dua lintasan.

Elektron dapat berpindah dari satu kulit ke kulit
lain disertai pemancaran atau penyerapan
sejumlah tertentu energi.
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RUTHERFORD’S ATOMIC MODEL
WAS UNSTABLE
Maxwell’s law
Electron
Moves around
Nucleus, with
an Opposite
charge
Actually, the
electrons do not join
the nucleus and the
atom remains stable.
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Electron will
experience
Acceleration and
emit energy
Electron can no
longer balance the
attracting forces of
the nucleus and
collapses into the
nucleus.
Energy of the
electron to
decrease.
Radius of the
electron’s orbit
decreases
Brings electron
closer to the
nucleus.
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MECANICA QUANTUM THEORY
 Erwin Schrodinger, 1927, mengelurkan teori
mekanika kuantum atau mekanika
gelombang.
 Persamaan dengan Niels bohr karena
adanya tingkat-tingkat energi atau kulit
atom,tapi berbeda dalam bentuk lintasan/
orbit tersebut.
 Dalam teori ini, posisi elektron adalah tidak
pasti.
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DEVELOPMENT OF ATOMS MODELS
Dalton
(1803)
Hal.: 16
Thomson
(1897)
Rutherford
(1910)
Model atom
Niels Bohr
(1913)
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Mekanika
Kuantum
(1926)
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PARTICLE OF ATOM
PROTON
POSITIVE CHARGE
Massa 1 proton = 1,6726486 x 10-24 gram = 1 sma
Muatan 1 proton = + 1 = +1,6 x 10-19 C
NUCLEUS
NEUTRON
NO CHARGE
Massa 1 neutron = 1,6749544 x10-24 gram = 1 sma
ATOM
NEGATIVE CHARGE
OUT OF
NUCLEUS
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ELEKTRON
Massa 1 elektron = 9,1093897 x 10-28gram =
1/ 1840 sma
Muatan 1 elektron = - 1 = - 1,6 x 10-19 C
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ATOM SYMBOL
Atom hidrogen
dengan satu proton dan elektron
dan tidak memiliki netron.
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ISOTOP, ISOBAR, ISOTON
ISOTOP
Atom-atom dari unsur yang sama mempunyai
massa yang berbeda
Contoh : C12, C13, C14
ISOBAR
Atom-atom dari unsur yang berbeda
mempunyai massa yang sama.
Contoh : 6 C14 dan 7 N14 , 11Na24 dan 12 Mg24
ISOTON
Atom-atom dari unsur yang berbeda
mempunyai jumlah neutron yang sama.
Contoh : 6C13 dan 7N14 , 15 P31 dan 16 S 32
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ELECTRON CONFIGURATION
 The arrangement of electrons in atom shells
is known as electron configuration.
 Every shells contain a number of electrons
follow the formula : 2 n 2 .
shell K (n =1)
Shell L (n =2)
Shell M (n =3)
Shell N (n =4)
Shell O (n =5)
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=
=
=
=
=
2 x 12
2 x 22
2 x 32
2 x 42
2 x 52
= 2
= 8
= 18
= 32
= 50
elektron
elektron
elektron
elektron
elektron
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DETERMINE ELECTRONS
CONFIGURATION
11Na
:
K
2
12Mg
:
2
13Al
35Br
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L
8
M
8
N
1
8
8
2
:
2
8
3
:
2
8
18
Valensi electrons
are used to form
chemical bonds
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THE MAIN QUANTUM NUMBER (N)
The Main Quantum Number (n)
are the number of electron in every level
of energy (2n2) with n is the main
quantum number
Quantum number for
Shell K ---- n = 1 Shell M ---- n = 3
Shell L ---- n = 2 Shell N ---- n = 4
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AZIMUT QUANTUM NUMBER (l )
 Indicate form and positition of orbital as probability
of electron arrangement and show the sub level of
energy.
 Azimut quantum number follow equal l = n – 1
 Azimut quantum number have value from 0 to n – 1
main
quantum
number
n
n
n
n
=
=
=
=
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1
2
3
4
azimut
quantum
number
---------
l
l
l
l
=
=
=
=
0
1
2
3
sub level of energy
(the place of electron)
s (sharp)
p (principle)
d (diffuse)
f (fundamental)
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MAGNETIC QUANTUM NUMBER (m)
Indicate the orientation of orbital in
space of atom.
Follow this equal --> m = (-l, + l)
Example for l = 1
m begin from -1, 0 , + 1
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SPIN NUMBER (s)
Describe the characteristic of electron
that rotate in their axis
produces two different of direction or
spin : + ½ dan – ½
s2
Px Py Pz
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The Electron Configuration
Pauli
 Two electron in an atom are imposible to have
the same four quantum number.
Aufbau
 Electrons in an atom fill orbitals with low level
of energy and followed to orbital with high
level of energy.
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d <
5p < 6s < 5d < 4f < 6p < 7s < 6d < 5f,
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TINGKAT ENERGI DALAM ATOM
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The example for determine
electron configuration
Atom with atomic number = 11
11
Na = 1s2
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2s2
2p6
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3s1
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The elements periodic system
•
Elements were grouped based on similar
properties.Later, they were based on
similar properties and increasing atomic
mass.
•
This led to the arrangement of elements in
a periodic system.
•
In modern periodic system, elements are
arranged based on increase of atomic
number and similar properties.
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The classification of elements
Classification of elements
Metals
And
Non metals
Lavoisier
Hal.: 30
Dobereiner’s
Triads
System
Johan
Wolfgang
Newlands’
Law
Octaves
A.R.Newland
Mendeleev’s
Periodic
system
Dmitry
Ivanovich
Mendeleev
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Modern’s
periodic
system
Henry G.
Moseley
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Dobereiner’s Triads
 Grouped elements based on similar properties in groups
of three called triads. In a triad, the properties of the
second element are in between the properties of the first
and third elements.
Li
Na
K Ca
Sr
Ba
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Newland’s law of Oktaves
 Classified elements in the increasing order of
their atomic masses.
 Because the repeating trend always occurs in
sets of eight, the system is known as the Law of
Octaves.
1. H
2. Li
3. Be 4. B
5. C
6. N
7. O
8.F
9. Na 10.Mg 11.Al 12.Si 13.P
14.S
15.Cl 16.K 17.Ca 18.Cr 19.Ti 20.Mn 21.Fe
22.Co 23.Cu 24.Zn 25.Y
26.In 27.As 28.Se
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Mendeleev’s periodic system
He arranged the elements based on
the increasing atomic mass
horizontally forming rows called
periods.
Elements with similar properties will
form column called groups.
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The modern periodic system
In the modern periodic system, elements
are classified based on the increasing
atomic number (Z) which is the
characteristic for every element.
The arrangement of elements based on
the increasing atomic number and
similarities in properties.
Produces a repetition of properties of
element in the form of periods (rows) and
columns.
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The modern periodic system
 The elements of A groups are called the
main group elements.
 Those of B groups are the transition
elements.
 The elements in the two long rows below
the main table are known as inner transition
elements, the first row is named the
lanthanide series and the second row is the
actinide series.
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The modern periodic system
 Group 1 A
: alkali metals.
(except Hidrogen)
 Group II A : alkaline earth metals.
 Group VIIA : halogens
 Group VIII A
: noble gases
Transition metals
Are groups between II A and III A consist of
less reactive metals.
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Periodic Properties of the Elements
 Atomic radius
is the distance from the nucleus to the outermost shell.
 The atomic radius decreases across a period.
 The atomic radius increases down a group.
 Ionization Energy (IE)
is defined as the energy required to remove an electron of
a gaseous atom or ion.
 The ionization energy increases across a period
 The ionization energy decreases down a group.
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Periodic Properties of the Elements
 Electron affinity
is the energy involved when a gaseous atom or
ion receives one electron to form a negative ion.
 The electron affinity tends to increase across a
periode.
 The electron affinity tends to decrease down a
group
 Electronegativity
is measure of the ability of an atom to attract
electrons in a chemical bond.
 The electronegativity increases across a period.
 The electronegativity decreases down a group.
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Periodic Properties of the Elements
Melting Points and Boiling Points
is the temperature at which the vapor
pressure of a solid is the same as the
vapor pressure of its liquid.
 In one period, the melting points and
boiling points initially increase until
group IVA, then decrease and reach the
lowest level at group VIIIA
 In one group, the melting points and
boiling points of metals decrease while
those of nonmetals increase.
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REFERENCES
Zulfikar, Kimia Kesehatan untuk SMK,
Jilid 1, Direktorat Pembinaan SMK,
Depdiknas,2008.
Michael Purba, KIMIA, untuk SMA kelas
X, Erlangga,2006
J.M.C.Johari,M.Rachmawati,Chemistry for
Senior High School Grade X, English
Edition,Esis,2009
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THANK YOU
FOR
YOUR ATTENTIONS
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