Mammoth Memory

Electron shells and 2,8,8

There are multiple shells or orbits of electrons around a nucleus, the closest orbits fill first but the first orbit only allows 2 the second 8 and the third 8
To remember how many electrons are allowed in each shell, think of two fat ladies (2, 8, 8) on a beach covered in shells.

 

Electronic shells explained

  1. Electrons always occupy these shells or orbits.

 

  1. The orbit or shell nearest to nucleus is filled first.

 

  1. Only a certain number of electrons are allowed in each shell:

 

  • The first orbit or shell allows 2
  • The second orbit or shell allows 8
  • The third orbit or shell allows 8

 

  1. Atoms are happier when there is a full electron shell

 

  1. If the outer shell is not full it will want to react

 

Examples:

Sodium

Sodium has 11 electrons orbiting its nucleusAtoms need all shells filling with the correct number if not it will react with other atoms to fill or release electrons sodium in this case wants to get rid of the single electron in its outer shell

Sodium has 11 electrons

Sodium has only one electron in its outer shell and therefore wants to get rid of it.

 

Chlorine  

Chlorine has 17 electrons orbiting its nucleusChlorine needs one more electron to fill its outer orbit and needs it badly so it reacts violently with other atoms

Chlorine has 17 electrons.

Chlorine needs one more electron to make a full shell and wants one badly.

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