Prinsip Aufbau: Perbedaan antara revisi

'''Prinsip Aufbau''' menyatakan bahwa, secara hipotetis, [[elektron]] yang mengorbit satu atau lebih [[atom]] mengisi [[tingkat energi]] terendah yang tersedia sebelum mengisi tingkat yang lebih tinggi (misalnya, 1s sebelum 2s). Dengan cara ini, elektron pada [[atom]], [[molekul]], atau [[ion]] menyelaraskan ke [[konfigurasi elektron]] yang paling stabil.

 

 

 

Satu versi prinsip Aufbau dikenal sebagai [[model kulit nuklir]] digunakan untuk memperkirakan konfigurasi [[proton]] dan [[neutron]] dalam [[inti atom]].<ref>{{cite book|last1 = Cottingham|first1 = W. N.|last2 = Greenwood|first2 = D. A.|title = An introduction to nuclear physics|publisher = Cambridge University Press|date = 1986|ISBN = 0 521 31960 9|chapter = Chapter 5: Ground state properties of nuclei: the shell model }}</ref>

 

The order in which these orbitals are filled is given by the ''n + &#x2113; rule'', also known as the '''Madelung rule''' (after [[Erwin Madelung]]), or the '''Janet rule''' or the '''Klechkowski rule''' (after [[Charles Janet]] or [[Vsevolod Klechkovsky]] in some, mostly French and Russian-speaking, countries), or the '''diagonal rule'''.<ref>{{cite web | url = http://www.wyzant.com/resources/lessons/science/chemistry/electron_configuration | title = Electron Configuration | publisher = [[WyzAnt]] }}</ref> Orbitals with a lower ''n + &#x2113;'' value are filled before those with higher ''n + &#x2113;'' values. In this context, ''n'' represents the [[principal quantum number]] and ''&#x2113;'' the [[azimuthal quantum number]]; the values ''&#x2113;'' = 0, 1, 2, 3 correspond to the ''s'', ''p'', ''d'', and ''f'' labels, respectively.

 

The Madelung energy ordering rule applies only to neutral atoms in their ground state, and even in that case, there are several elements for which it predicts configurations that differ from those determined experimentally.<ref>{{cite journal |last=Meek |first=Terry L. | last2 = Allen | first2 = Leland C. |title=Configuration irregularities: deviations from the Madelung rule and inversion of orbital energy levels |journal=[[Chemical Physics Letters|Chem. Phys. Lett.]] |volume=362 |issue=5–6 |pages=362–64 |doi=10.1016/S0009-2614(02)00919-3 |date=2002 |bibcode=2002CPL...362..362M }}</ref> [[Copper]], [[chromium]], and [[palladium]] are common examples of this property. According to the Madelung rule, the 4s orbital (''n + &#x2113;'' = 4 + 0 = 4) is occupied before the 3d orbital (''n + &#x2113;'' = 3 + 2 = 5). The rule then predicts the configuration of ₂₉Cu to be 1s²2s²2p⁶3s² 3p⁶4s²3d⁹, abbreviated [Ar]4s²3d⁹ where [Ar] denotes the configuration of Ar (the preceding noble gas). However the experimental electronic configuration of the copper atom is [Ar]4s¹3d¹⁰. By filling the 3d orbital, copper can be in a lower energy state. Similarly, chromium takes the electronic configuration of [Ar]4s¹3d⁵ instead of [Ar]4s²3d⁴. In this case, chromium has a half-full 3d shell. For palladium, the Madelung rule predicts [Kr]5s²4d⁸, but the experimental configuration [Kr]4d¹⁰ differs in the placement of two electrons.

 

 

 

 

A periodic table in which each row corresponds to one value of ''n + &#x2113;'' was suggested by [[Charles Janet]] in 1927. In 1936, the German physicist [[Erwin Madelung]] proposed his empirical rules for the order of filling atomic subshells, based on knowledge of atomic ground states determined by the analysis of atomic spectra, and most English-language sources therefore refer to the Madelung rule. Madelung may have been aware of this pattern as early as 1926.<ref>{{cite journal |title= The Order of Electron Shells in Ionized Atoms |last1= Goudsmit |first1= S. A. |last2= Richards |first2= Paul I. |journal= [[Proceedings of the National Academy of Sciences of the United States of America|Proc. Natl. Acad. Sci.]] |pages= 664–671 (with correction on p&nbsp;906) |volume= 51 | issue= 4 |date= 1964 |url= http://www.pnas.org/content/51/4/664.full.pdf |bibcode = 1964PNAS...51..664G |doi = 10.1073/pnas.51.4.664 }}</ref> In 1962 the Russian agricultural chemist [[V.M. Klechkovsky|V.M. Klechkowski]] proposed the first theoretical explanation for the importance of the sum ''n + &#x2113;'', based on the statistical [[Thomas–Fermi model]] of the atom.<ref>{{cite journal | title = Theoretical justification of Madelung's rule | journal = [[Journal of Chemical Education|J. Chem. Ed.]] | url = http://jchemed.chem.wisc.edu/Journal/Issues/1979/Nov/jceSubscriber/JCE1979p0714.pdf | last = Wong | first = D. Pan | date = 1979 | issue = 11 | pages = 714–718 | volume = 56 | doi = 10.1021/ed056p714|bibcode = 1979JChEd..56..714W }}</ref> Many French- and Russian-language sources therefore refer to the Klechkowski rule.

 

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Urutan-urutan tingkat energi di tujukan pada gambar di samping kanan. Jadi pengisian orbital dimulai dari orbital 1s, 2s, 2p, dan seterusnya. Pada gambar dapat dilihat bahwa subkulit 3d mempunyai energi lebih tinggi daripada subkulit 4s<ref name=":0">{{cite|last=Chang|first=R.|year=2007|title=Kimia Dasar (terj)|publisher=Erlangga|location=Jakarta}}</ref>. Oleh karena itu, setelah 3p terisi penuh maka elektron berikutnya akan mengisi subkulit 4s, baru kemudian akan mengisi sub kulit 3d.<ref name=":1">{{cite|last=Keenan|year=1990|title=General Chemistry|publisher=Elsiever|location=Boston}}</ref>

 

== Langkah-langkah penulisan konfigurasi elektron ==

# Menuliskan jenis subkulit yang dibutuhkan secara urut berdasarkan diagram curah hujan pada gambar 2 yaitu :  1s- 2s- 2p- 3s- 3p- 4s- 3d- 4p- 5s- 4d- 5p- 6s- 4f- 5d- 6p- 7s- 5f- 6d- 7p- 8s

# Mengisikan elektron pada masing-masing subkulit dengan memperhatikan jumlah elektron maksimumnya, maka sisa elektron dimasukan pada subkulit berikutnya<ref name=":1" />.

 

== Referensi ==