standar kompetensi: memahami struktur atom, sifat-sifat periodik unsur, dan ikatan kimia

Periodical Development By Farid 2008

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Standar Kompetensi : 1. Memahami struktur atom, sifat-sifat periodik

unsur, dan ikatan kimiaKompetensi dasar:1.1. Memahami struktur atom berdasarkan teori

atom Bohr, sifat-sifat unsur, massa atom relatif, dan sifat-sifat periodik unsur dalam tabel periodik serta menyadari keteraturannya, melalui pemahaman konfigurasi elektron.

Indikator:1. Membandingkan perkembangan tabel periodik

unsur untuk mengidentifikasi kelebihan dan kekurangannya.

2. Menjelaskan dasar pengelompokan unsur-unsur.


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At present, scientists have succesfuly finding and identify about 118 element, and 90 element among other are the element which there are in nature (nature element), while the remainder (sisanya) are the artificial elements (unsure buatan). Because of the elements in nature are plenty (sangat banyak), hence to facilitate (memudahkan) us to study and identify a given element. The scientists try to group the elements in a given group based on their similar properties.


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For begining, elements are grouped on their metallic properties based only, those are become the metallic element, nonmetallic and semi metallic element (metalloid). However, then element grouped in periodic tables based on atomic number and atomic mass number of that elements. The following are explanations about history of element grouping development since early until present.


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1. Dobreiner TriadsAccording to Johann Wolfgang Dobreiner, if a triad

consist of element A, B and C, so the average sum of atomic mass of A and atomic mass of B is equal to the atomic mass of C. In this case A, B and C are the element with similar properties.

The examples of triads are :Cl , Br , I Ca, Sr , BaS , Se , TeFe,Co , Mn


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Meanwhile, its weakness is the limited number of element which can be grouped in triads and the confusion (kesulitan) about the existed concerning the distinction (perbedaan) between atomic weights and molecular weights,

2. Newlands OctaveIn 1859 the German physicists John A.R.

newlands listed the elements in the order based on the increase of atomic weights and he noted that a given properties of the elements in the list, recurs at every eighth element.


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11 22 33 44 55 66 77

HH LiLi BeBe BB CC NN OO

FF NaNa MgMg AlAl SiSi PP SS

ClCl KK CaCa CrCr TiTi MnMn FeFe

Co, NiCo, Ni CuCu ZnZn YY InIn AsAs SeSe


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HH FF ClCl Co/NiCo/Ni BrBr PdPd II Pt/IrPt/Ir

LiLi NaNa KK CuCu RbRb AgAg CsCs TlTl

BeBe MgMg CaCa ZnZn SrSr CdCd Ba/VBa/V PbPb

BB AlAl CrCr YY Ce/LaCe/La UU TaTa ThTh

CC SiSi TiTi InIn ZrZr SnSn WW HgHg

NN PP MnMn AsAs Di/MoDi/Mo SbSb NbNb BiBi

OO SS FeFe SeSe Ro/RuRo/Ru TeTe AuAu OsOs


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Newlands octave has the excess (kelebihan) compared than Dobreiner triads, that is the more classified elements.Meanwhile, its weakness is at element which its mass is large enough (>40), the element properties repletion is not happened any more, so that elemens grouping based on Newlands octave is not used in present day. Or the law octaves has weakness that is the suitable only at elements which its mass is small.


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3. Mendeleev’s Periodic TableIndependently, Russian chemist Dmitry Mendeleev

in 1869 and German chemist Julius Lothar Meyer in 1870 proposed a chemical law that the properties of all the elements are periodic functions of their atomic mass. According to that the law (periodic law), Mendeleev and Meyer grouped about 66 elements based on the increases of their atomic mass.Mendeleev give a place elements having similar properties in a coulomn called GROUP.


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ReihenReihen(Period(Periode)e)

Grouppe Grouppe II

Grouppe Grouppe IIII

Grouppe Grouppe IIIIII

Grouppe Grouppe IVIV

Grouppe Grouppe VV

Grouppe Grouppe VIVI

Grouppe Grouppe VIIVII

Grouppe Grouppe VIIIVIII

11 H=1H=1

22 Li=7Li=7 Be= 9,2Be= 9,2 B= 11B= 11 C= 12C= 12 N= 14N= 14 O= 16O= 16 F= 19F= 19

33 Na= 23Na= 23 Mg= 24Mg= 24 Al= 27,3Al= 27,3 Si= 28Si= 28 P= 31P= 31 S= 32S= 32 Cl= 35,5Cl= 35,5

44 K= 39K= 39 Ca= 40Ca= 40 - = 44- = 44 Tl= 48Tl= 48 V= 51V= 51 Cr= 52Cr= 52 Mn= 55Mn= 55 F=56, F=56, Co=59Co=59

55 (Cu= 63)(Cu= 63) Zn= 65Zn= 65 - = 68- = 68 - = 72- = 72 As= 75As= 75 Se= 78Se= 78 Br= 80Br= 80

66 Rb= 85Rb= 85 Sr= 87Sr= 87 ?Yt= 88?Yt= 88 Zr= 90Zr= 90 Nb= 94Nb= 94 Mo= 96Mo= 96 - = 100- = 100 Ru=104, Ru=104, Rh=104Rh=104Pd=106, Pd=106, Ag=108Ag=108

77 (Ag= 108)(Ag= 108) Cd=112Cd=112 In= 113In= 113 Sn= 118Sn= 118 Sb= 122Sb= 122 Te= 125Te= 125 J= 127J= 127

88 Cs= 133Cs= 133 Ba= 137Ba= 137 ? Di= 138? Di= 138 -- -- -- -- ------------

99 -- -- -- -- -- --

1010 -- -- ? Er= 178? Er= 178 ? ? La= 180La= 180

Ta= 182Ta= 182 W= 184W= 184 -- Os=195, Os=195, Ir=197Ir=197Pt=198, Pt=198, Au=199Au=199

1111 (Au=199)(Au=199) Hg= 200Hg= 200 Ti= 204Ti= 204 Pb= 207Pb= 207 Bi= 208Bi= 208 --

1212 -- -- Th= 231Th= 231 -- U= 240U= 240 -- ------------


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Mendeleev’s Periodic table has some excess compared than Newlands Octave, those are:Giving correction to some values of relative atomic mass of the element. The example of the relative atomic mass of Uranium is changed from 10 become 240 and Beryllium for 13 become 9.Mendeleev take place the tellurium element (128) before iodine (127).


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Mendeleev’s Periodic table (has weakness) is still has the lack (kekurangan), that is some sequence (urutan) of the elements placement apparently (ternyata) inappropriate (unsuitable) with the increase of their atomic mass.

Mendeleev set a side a vacant space from his table. Then this place was later assigned to the element scandium, discovered in 1879, which has properties justifying its position in that periodic table.The placement of the noble gasses in the mendeleev’s periodic table do not modify the early formation of the other elements.


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4. Short-Form Periodic TableThe raising of new element discoveries during period

of 1817-1898 caused the Mendeleev’s periodic table become no longer be relevant to classify the element. Therefore, in 1930 the scientists developed the new periodic table which is the development of mendeleev’s periodic table. The periodic table is recognized (dikenal) as the short-form periodic table.


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Group Group 00

II IIII IIIIII IVIV VV VIVI VIIVII VIIIVIII

a ba b a ba b a ba b a ba b a a bb

a ba b a a bb

a ba b

HH

HeHe LiLi BeBe BB CC NN OO FF

NeNe NaNa MgMg AlAl SiSi PP SS ClCl

ArAr K K CuCu

Ca Ca ZnZn

Sc GaSc Ga Ti Ti GeGe

V V AsAs

Cr Cr SeSe

Mn Mn Br Br

Fe,Co,NiFe,Co,Ni

KrKr Rb Rb AgAg

Sr CdSr Cd Y InY In Zr Zr SnSn

Nb Nb SbSb

Mo Mo TeTe

- - 153153

Ru,Rh,PdRu,Rh,Pd

XeXe Cs Cs AuAu

Ba Ba HgHg

57-71* 57-71* TlTl

Hf Hf PbPb

Ta Ta BiBi

W W PoPo

Re -Re - Os,Ir,PtOs,Ir,Pt

RnRn RaRa AcAc ThTh PaPa UU


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5. Long-Form Periodic table (Modern Periodic Table)In 1914 Henry G.J. Moseley found that the properties

of element are periodic function of their atomic number. Based on that case, so the short-form periodic table developed become the long-form periodic table, then this periodic table completed become the modern periodic table ratified (disahkan) its use by IUPAC (The International Union of Pure and Applied Chemists) in 1923.In modern periodic table, element take placed at row called period and group. In this case, period is the placement row of the elements is in the horizontal lines, meanwhile, group is the placement of the elements is in the vertical columns.


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PeriodPlacement of element in period are relied on the periodical properties of element that according to the order of their atomic number alteration (perubahan). In modern periodic table, element are grouped into 7 period that consist of:

shortest period (period 1 consist of 2 elements)short period (period 2 and period 3, each consist of 8 elements)Long period (period 4 and period 5, each consist of 18 elements)Longest period (period 6, consist of 32 elements)Uncomplete period (period 7)


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GroupElements which take placed in one group are the elements having the similar properties of one another . The group of element in periodic table is distinguished (dibedakan) into principal group (group A) and transition group (group B)


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Modern Periodic System Modern Periodic System (Moseley)(Moseley)

ElementElement characteristics are the characteristics are the periodic function of the atom number-periodic function of the atom number-NOT the atom mass.NOT the atom mass.

In the year of 1985, IUPAC establishes In the year of 1985, IUPAC establishes (menetapkan) a Modern Periodic (menetapkan) a Modern Periodic System.System.


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B. Groups Periods of Elements B. Groups Periods of Elements in Periodic Systemin Periodic System

1.1. GroupGroup

Group are columns in Group are columns in periodic systemperiodic system


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Modern Periodic SystemModern Periodic System

Consists of :Consists of :

a.a. 8 major groups ( I A – VIII A )8 major groups ( I A – VIII A )

b.b. 8 Transition groups ( I B – III B )8 Transition groups ( I B – III B )

c.c. Internal transition groups Internal transition groups ( Lantanida and Actinida )( Lantanida and Actinida )


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For major groups, they are:For major groups, they are:

a.a. IA group ( alkaline metal group)IA group ( alkaline metal group)

Li , Na , K , Rb , Cs , FrLi , Na , K , Rb , Cs , Fr

b.b. IIA group ( earth alkaline metal IIA group ( earth alkaline metal group )group )

Be , Mg , Ca , Sr , Ba , RaBe , Mg , Ca , Sr , Ba , Ra

c.c. IIIA group ( aluminium group )IIIA group ( aluminium group )

B , Al , Ga , In , TlB , Al , Ga , In , Tl


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d. IVA group ( carbon group )d. IVA group ( carbon group )

Ca , Si , Ge , Sn , PbCa , Si , Ge , Sn , Pb

e. VA group ( nitrogen group )e. VA group ( nitrogen group )

N , P , As , Sb , BiN , P , As , Sb , Bi

f. VIA group ( khalkogen / oxygen group )f. VIA group ( khalkogen / oxygen group )

O , S , Se , Te , PoO , S , Se , Te , Po

g. VIIA group ( halogen group )g. VIIA group ( halogen group )

He , Ne , Ar , Kr , Xe , RnHe , Ne , Ar , Kr , Xe , Rn

standar kompetensi: memahami struktur atom, sifat-sifat periodik unsur, dan ikatan kimia

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