1.atomic sructure

PARTIKEL DASAR PENYUSUN ATOM

MODEL ATOM

NOMOR ATOMNOMOR MASSAISOTOP, ISOBAR

ISOTON

KONFIGURASI ELEKTRON

STRUKTUR ATOM

Hal.: 4 Isi dengan Judul Halaman Terkait

THE ATOMIC THEORY

ATOMIC THEORY

DEMOCRITUS

THOMSON

DALTON

RUTHERFORDNIELS BOHR

MODERN

Hal.: 5

DEMOCRITUS (460 -370 SM)

The tiny particles could not be divided to any further estent are called ATOMS

A. MODEL ATOM JOHN DALTON TEORI YG DIKEMUKAKAN :1. atom adalah bagian terkecil suatu unsur 2. atom digambarkan sebagai bola pejal yg sangat kecil, suatu unsur memiliki atom2 yg identik dan berbeda untuk unsur yg berbeda3. atom2 bergabung membentuk senyawa dengan perbandingan bilangan bulat dan sederhana4. Reaksi kimia meruipakan pemisahan atau penggabungan atau penyusunan kembali dari atom2, sehingga atom tidak dapat dimusnahkan atau diciptakan

Model atom Dalton, seperti

bola pejal


B. THOMSON’S ATOMIC MODEL

Thomson proposed an atomic model called RAISIN PLUM PUDDING MODELThomson described atom as a positively charged sphere containing several negatively charged particles called ELECTRONS. The electrons are scattered in the sphere like raisins in a plum pudding

C. MODEL ATOM RUTHERFORD

1.Atom adalah bola berongga yg tersusun dari inti atom dan elektron yg mengelilinginya. 2.Inti atom bermuatan positif dan massa atom terpusat pada inti atom

MODEL TATA SURYA


D. NIELS BOHR’S ATOMIC MODEL AND MODERN’S ATOMIC MODEL

Membebaskan Energi

Elektron

Elektron

MenyerapEnergi

IntiAtom

Niels Bohr succeeded in overcoming the weakness of the Rutherford’s atomic model


.Model atom menurut Niels Bohr, 1913:1. Atom terdiri dari inti yg bermuatan positif

dan dikelilingi elektron yg bermuatan negatif di dalam suatu lintasan

2. Elektron dapat berpindah dari satu lintasan ke lintasan yg lain dengan menyerap atau memancarkan energi sehingga energi elektron atom itu tidak akan berkurang

3. Jika elektron berpindah lintasan ke lintasan yg lebih tinggi, maka elektron akan menyerap energi. Jika elektron berpindah ke lintasan yg lebih rendah akan memancarkan energi


DEVELOPMENT OF ATOMS MODELS

Dalton(1803)

Thomson(1897)

Rutherford(1910)

Model atom Niels Bohr

(1913)

MekanikaKuantum

(1926)


MECANICA QUANTUM THEORY

Erwin Schrodinger, 1927, mengelurkan teori mekanika kuantum atau mekanika gelombang.

Kulit-kulit elektron bukan merupakan kedudukan yg pasti dari suatu elektron, tetapi hanyalah suatu kebolehjadian saja. Dengan demikian kedudukan dan kecepatan gerakan elektron dalam atom berada di ruang tertentu dalam atom disebut ORBITAL

A. Partikel dasar :

partikel-partikel pembentuk atom yang terdiri dari proton, elektron dan neutron.

1. Proton

partikel pembentuk atom yang mempunyai massa sma dengan satu sma (amu) dan bermuatan +

2. Elektron

partikel pembentuk atom yang tidak mempunyai massa dan bermuatan -

3. Neutron

partikel pembentuk atom yang bermassa satu sma (amu) dan netral.

B. Nukleus

Inti atom yang bermuatan positif, terdiri dari proton dan neutron.

PARTIKEL DASAR PENYUSUN ATOM

1. Discovery of the ElectronIn 1897, J.J. Thomson used a cathode ray tube to deduce the presence of a negatively charged particle: the electron

Nilai hasil pengukuran Thomson tentang rasio antara muatan elektron (e) dan massa elektron m adalah : e/m = -1,7588196. 1011 C/kg

Mass of the Electron

1916 – Robert Millikan determines the mass of the electron: 1/1840 the mass of a

hydrogen atom (me = 9,1093897 . 10-31 kg)

The oil drop apparatus

Mass of the electron is

9.11 x 10-28 g,l

PENEMUAN PROTON


Jika massa elektron = 0, berarti suatu partikel tdk mempunyai massa.padahal partikel materi mempunyai massa yg dapat diukur.Jadi bagaimana mungkin atom bersifat netral dan mempunyai massa jika hanya ada elektron saja di dlm atom?????

GOLDSTEIN melakukan eksperimen menggunakan tabung gas yg memiliki katode. Ternyata pada saat terbentuk elektron yg menuju anode, terbentuk pula sinar positif yg menuju arah berlawanan melewati lubang katode


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 spaceGo straight through.

Alpha particles that approach the nucleus are deflected.

Alpha particles that hit the nucleus are bounced back

nucleon

electron




Rutherford berhasil mengukur massa inti atom yg kira-kira dua kali dari massa proton dalam inti. Sehingga, menurut Rutherford harus ada partikel lain di dalam inti atom dan partikel tersebut tidak bermuatan.

Baru pada tahun 1932, J.CHADWICK menemukan NEUTRON dari penembakan berilium menggunakan partikel2 alfa dan kemu dian neutron ini diketahui sebagau partikel penyusun inti atomNeutron merupakan partikel tidak bermuatan dengan massa kira-kira 1,67 x 10-27 kg


PARTICLE OF ATOM

ATOM

NUCLEUS

OUT OF NUCLEUS

PROTON

NEUTRON

ELEKTRON

POSITIVE CHARGEMassa 1 proton = 1,6726486 x 10-24 gram = 1 sma

Muatan 1 proton = + 1 = +1,6 x 10-19 C

NO CHARGEMassa 1 neutron = 1,6749544 x10-24 gram = 1 sma

NEGATIVE CHARGEMassa 1 elektron = 9,1093897 x 10-28gram =

1/ 1840 sma

Muatan 1 elektron = - 1 = - 1,6 x 10-19 C


ATOM SYMBOL

Atom hidrogendengan satu proton dan elektron

dan tidak memiliki netron.

Notasi unsur : ZA X

dengan X : tanda atom (unsur)

Z : nomor atom = jumlah elektron (e) = jumlah proton (p)

A : bilangan massa = jumlah proton + neutron

‘’Pada atom netral, berlaku: jumlah elektron = jumlah proton’’

CONTOH SOAL

1. Tentukan jumlah elektron, proton den neutron dari unsur 26

56 Fe !

Jawab : Jumlah elektron = jumlah proton = nomor atom = 26 Jumlah neutron = bilangan massa - nomor atom = 56 - 26 = 30

2. Berikan notasi unsur X, jika diketahui jumlah neutron = 14 dan jumlah elektron = 13 !

Jawab : Nomor atom = jumlah elektron = 13 Bilangan massa = jumlah proton + neutron = 13 + 14 = 27 Jadi notasi unsurnya : 13

27 X



ISOTOP, ISOBAR, ISOTON

ISOTOP Atom-atom dari unsur yang sama mempunyai massa yang berbedaContoh : C12, C13, C14

ISOBARAtom-atom dari unsur yang berbeda mempunyai massa yang sama.Contoh : 6 C14 dan 7 N14 , 11Na24 dan 12 Mg24

ISOTONAtom-atom dari unsur yang berbeda mempunyai jumlah neutron yang sama.Contoh : 6C13 dan 7N14 , 15 P31 dan 16 S 32


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) = 2 x 12 = 2 elektronShell L (n =2) = 2 x 22 = 8 elektronShell M (n =3) = 2 x 32 = 18 elektronShell N (n =4) = 2 x 42 = 32 elektronShell O (n =5) = 2 x 52 = 50 elektron


DETERMINE ELECTRONS CONFIGURATION

K L M N

11Na : 2 8 8 1

12Mg : 2 8 8 2

13Al : 2 8 3

35Br : 2 8 18 7

Valensi electrons are used to form chemical bonds


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 numberQuantum number forShell K ---- n = 1 Shell M ---- n = 3Shell L ---- n = 2 Shell N ---- n = 4


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 – 1main azimut sub level of energyquantum quantum (the place of electron)number number

n = 1 --- l = 0 s (sharp) n = 2 --- l = 1 p (principle) n = 3 --- l = 2 d (diffuse) n = 4 --- l = 3 f (fundamental)


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


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


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,


TINGKAT ENERGI DALAM ATOM


The example for determine electron configuration

Atom with atomic number = 11

11 Na = 1s2 2s2 2p6 3s1


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.


The classification of elements

Classification of elements

MetalsAnd

Non metals

Dobereiner’sTriadsSystem

Newlands’Law

Octaves

Mendeleev’sPeriodicsystem

Modern’s periodicsystem

Lavoisier JohanWolfgang

A.R.Newland Dmitry Ivanovich

Mendeleev

Henry G.Moseley


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.

Ca

Sr

Ba

Li

K

Na


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. O8.F 9. Na 10.Mg 11.Al 12.Si 13.P 14.S15.Cl 16.K 17.Ca 18.Cr 19.Ti 20.Mn 21.Fe22.Co 23.Cu 24.Zn 25.Y 26.In 27.As 28.Se


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.


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.



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.



Group 1 A : alkali metals. (except Hidrogen)

Group II A : alkaline earth metals. Group VIIA : halogens Group VIII A : noble gases

Transition metalsAre groups between II A and III A

consist ofless reactive metals.


Periodic Properties of the Elements

Atomic radiusis 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.



Electron affinityis 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

Electronegativityis 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.



Melting Points and Boiling Pointsis 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.


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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1.atomic sructure