Periodic table period
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In the periodic table of the elements, a period is a row of the table.
The number of electron shells an atom has determines what period it belongs to. Each shell is divided into different subshells, which as atomic number increases are filled in roughly this order:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s 5g 6f 7d 8p ...
Hence the structure of the periodic table. Since the outermost 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. Elements adjacent to one another within a period have similar mass but different properties.
See also:
- Period 1 element
- Period 2 element
- Period 3 element
- Period 4 element
- Period 5 element
- Period 6 element
- Period 7 element
Template:PeriodicTablesFooterbg:Период на периодичната система ca:Perode de la taula peridica de:Periode des Periodensystems es:Periodo de la tabla peridica eo:Periodo de la perioda tabelo ko:주기율표 주기 it:Periodo della tavola periodica nl:Periodieke tabel, periode nn:Periodesystemets perioder ja:元素の周期 ro:Perioadele tabelului periodic su:Periode tabel periodik sv:Periodiska systemets perioder zh:元素周期