C4 - Electron Shells

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  • Created by: 11mbrady
  • Created on: 17-02-16 18:18

C4

ELECTRON SHELLS

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Electron Shells

Electron Shells:

  • Electrons always occupy shells
  • Lowest shells are always filled first
  • In the 1st Shell there is 2,  2nd Shell there is 8, 3rd Shell there is 8
  • Atoms are happier when they have full electrons
  • In most atoms the outer shell is not full and this makes the atom want to react

(http://www.passmyexams.co.uk/GCSE/chemistry/images/atom-diagram.jpg)

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Electron Configuration

How to work out the electron configurations:

  • Find the element in the periodic table and circle the proton number 
  • eg. Nitrogen has a proton number of 7
  • 2. Whatever the number of protons is,the number of electrons is the same
  • eg. Nitrogen has 7 protons so it must have 7 electrons
  • 3. Follow the electron shell rules. The first shell can only take 2 electrons and the second shell can take a maximum of 8 electrons
  • So the electron configuration for nitrogen must be 2 , 5 ( 2 + 5 = 8 )

Example (Argon)

  • Proton number of 18
  • 2 in the first shell, 8 in the second shell and then there has to be 8 in the 3rd as well
  • 2 , 8, 8  (2+8+8=18)
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