Chemical elements of the third period

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The third period of the periodic table of the elements contains all chemical elements that have exactly three electron shells in the atom . The innermost (first) electron shell is fully occupied and has two electrons . The second electron shell is also fully occupied and has eight electrons. The outermost (third) electron shell, also known as the valence shell , can hold between one to eight electrons, which is why there are eight chemical elements in the third period.

Extract from the periodic table

group 1 2 13 14th 15th 16 17th 18th

I. II III IV V VI VII VIII
Atomic number
symbol 		11
Well 		12
mg 		13
Al 		14
Si 		15
p 		16
pp 		17
cl 		18
ares


Alkali metals Alkaline earth metals other metals Semi-metals other non-metals Halogens Noble gases

Number of electrons in the electron shells

Electron shell Number of electrons comment
All in all s orbital p orbital d orbital f orbital
1 2 2 - - - innermost electron shell
2 8th 2 6th - -
3 1 to 8 1 to 2 0 to 6 - - outermost electron shell , valence shell

list

Atomic number symbol Surname Element category Physical state Electron configuration
11 N / A sodium Alkali metals firmly [ Ne ] 3s 1
12 Mg magnesium Alkaline earth metals firmly [Ne] 3s 2
13 Al aluminum other metals firmly [Ne] 3s 2 3p 1
14th Si Silicon Semi-metals firmly [Ne] 3s 2 3p 2
15th P phosphorus other non-metals firmly [Ne] 3s 2 3p 3
16 S. sulfur other non-metals firmly [Ne] 3s 2 3p 4
17th Cl chlorine Halogens gaseous [Ne] 3s 2 3p 5
18th Ar argon Noble gases gaseous [Ne] 3s 2 3p 6