How do you determine the number of electrons needed to fill the outer shell of an element?

1 Answer
Dec 25, 2017

Answer:

#2n^2#

Explanation:

The number of valence electrons needed to fill its shell can be determined by inputting the shell level, n, squaring it, and by multiplying by 2.

  • Shell 1 holds 2 valence #e^-#.
    #2(1^2)=2#
  • Shell 2 = 8
    #2(2^2)=8#
  • Shell 3 = 18
    #2(3^2)=18#
  • Shell 4 = 32
    #2(4^2)=32#
  • Shell 5 = 50
    #2(5^2)=50#

You can decide whether you want to memorize the sequence in which each level can hold, "2, 8, 18, 32, 50, etc.," or you can remember this simple function of #2n^2# for a quick reference.