Periodic table period
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:
Referenced By
Alkali earth metal | Alkali earth metals | Alkaline Earth | Alkaline Earth metals | Alkaline earth metal | Electron affinity | Electron orbital | Electronegative | Electronegativity | Group 2 | Group 2 element | Group 3 element | Group 4 element | Pauling Electronegativity Scale | Period 1 element | Period 2 element | Period 3 element | Period 4 element | Period 5 element | Period 6 element | Period 7 element | Periodic Table | Periodic Table of the Elements | Periodic table/Anti Table | Periodic table/Big Table | Periodic table/Huge Table | Periodic table/Metals and Non Metals | Periodic table/Standard Table | Periodic table/Table only | Periodic table (anti) | Periodic table (big) | Periodic table (block) | Periodic table (huge) | Periodic table (metals and non-metals) | Periodic table (standard) | Periodic table group | Periodic table of elements | Periodic table of the chemical elements
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