Period (periodic table)

(Redirected from Periods)
Jump to navigation Jump to search


In the periodic table of the elements, a period is a horizontal row of the table.

The elements are laid out in a series rows so that those with similar properties line up in vertical columns: this reflects the periodic recurrence of similar properties as the atomic weight increases.

Modern quantum mechanics explains these periodic trends in properties in terms of electron shells. As atomic number increases, electron shells are filled in roughly this order. The filling of each shell corresponds to a row in the table.

1s 
2s          2p  
3s          3p  
4s       3d 4p  
5s       4d 5p
6s    4f 5d 6p  
7s    5f 6d 7p  
      6f 7d    7f

...  

Hence the structure of the periodic table. Since the valence electrons determine chemical properties, those tend to be similar within periodic table groups.

Elements adjacent to one another within a group have similar physical properties, despite their significant differences in mass. In the d-block of the periodic table, periodic trends across periods become significant, and the f-block elements show a high degree of similarity across rows (particularly the lanthanides).

Template:PeriodicTablesFooter

af:Periode (periodieke tabel) ar:دورة جدول دوري ast:Periodu de la tabla periódica bn:পর্যায় সারণীর পর্যায় bs:Perioda periodnog sistema elemenata bg:Период на периодичната система ca:Període de la taula periòdica de:Periode des Periodensystems eo:Periodo de la perioda tabelo eu:Taula periodikoaren periodo ko:주기율표 주기 id:Periode tabel periodik is:Lota (lotukerfið) it:Periodo della tavola periodica lmo:Períut de la taula periòdica hu:Periódusos rendszerbeli periódus ms:Kala jadual berkala nl:Periode (scheikunde) nn:Periodane i periodesystemet nds:Periood (Chemie) simple:Periodic table period sk:Perióda (periodická tabuľka) sr:Периода периодног система елемената sh:Perioda periodnog sistema elemenata su:Periode tabel periodik fi:Jakso (jaksollinen järjestelmä) sv:Periodiska systemets perioder th:คาบในตารางธาตุ ur:دور (دوری جدول)


Template:WikiDoc Sources