Envision that you have virtually finished a an excellent meal, but cannot put one more bite in her mouth because there is no location for it come go. The noble gases have the exact same problem—there is no room for any more electrons in their outer shells. Castle are completely full and also cannot handle any more.

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## Noble Gas Configuration

Sodium, element number 11, is the an initial element in the third duration of the regular table. That is electron configuration is (1s^2 2s^2 2p^6 3s^1). The first ten electrons of the salt atom room the inner-shell electrons and also the construction of just those ten electron is exactly the same as the construction of the facet neon (left( Z=10 ight)). This gives the basis for a shorthand notation for electron configurations called the noble gas configuration. The elements that are discovered in the last tower of the regular table are an important group of aspects called the noble gases. They space helium, neon, argon, krypton, xenon, and radon. A noble gas configuration of an atom consists of the element symbol of the critical noble gas before that atom, adhered to by the configuration of the remaining electrons. So for sodium, we make the substitution of (left< ceNe ight>) for the (1s^2 2s^2 2p^6) part of the configuration. Sodium"s noble gas construction becomes (left< ceNe ight> 3s^1). Table (PageIndex1) mirrors the noble gas construction of the third duration elements.

Table (PageIndex1): Electron construction of Third-Period aspects Element NameSymbolAtomic NumberNoble Gas Electron Configuration
Sodium (ceNa) 11 (left< ceNe ight> 3s^1)
Magnesium (ceMg) 12 (left< ceNe ight> 3s^2)
Aluminum (ceAl) 13 (left< ceNe ight> 3s^2 3p^1)
Silicon (ceSi) 14 (left< ceNe ight> 3s^2 3p^2)
Phosphorus (ceP) 15 (left< ceNe ight> 3s^2 3p^3)
Sulfur (ceS) 16 (left< ceNe ight> 3s^2 3p^4)
Chlorine (ceCl) 17 (left< ceNe ight> 3s^2 3p^5)
Argon (ceAr) 18 (left< ceNe ight> 3s^2 3p^6)

Again, the variety of valence electrons boosts from one come eight throughout the third period.

The fourth and subsequent durations follow the very same pattern, except for the use ofa various noble gas. Potassium has nineteen electrons, one much more than the noble gas argon, for this reason its configuration can be created as (left< ceAr ight> 4s^1). In a comparable fashion, strontium has actually two an ext electrons than the noble gas krypton, i beg your pardon would allow us to compose its electron configuration together (left< ceKr ight> 5s^2). All elements can be stood for in this fashion.

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## Summary

The noble gas construction system enables some shortening of the full electron configuration by making use of the symbol because that the noble gas of the previous period as part of the pattern of electrons.