CHEM 1R03 Lecture Notes - Lecture 30: Electron Configuration, Noble Gas, Valence Electron
27 Apr 2018
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Chemistry Lecture 29 Continuation and Lecture 30
•Whenever figuring out the electron configuration of an element, you write it using
the symbol of the previous noble gas
•For example, the electron configuration of phosphorous is 1s22s22p63s23p3
•The noble gas that comes before phosphorous (going backwards on the periodic
table) is Neon whose electron configuration is 1s22s22p6
•So now to write the electron configuration of phosphorous using this noble gas, you
write the end part of phosphorous’s electron configuration where neon’s electron
configuration ends
•In simpler terms, both elements have 1s22s22p6 however neon does not have
3s23p3 so therefore, you write this as the electron configuration of phosphorous:
[Ne] = 3s23p3
Ionization Energy
•Ionization energy is the minimum energy required to remove a valence electron
from an atom
•The lower the ionization energy, the easier it is to remove the electron
•Metals have low ionization energies
•Ionization energy decreases going down and also from going right to left
