Chemists use the rules outlined in the previous section for quantum number to describe the position and spin of each electron around the nucleus of the atom. Chemists use various electron notations to illustrate these positions and spins.
1. The first is termed orbital notation .
This notation uses arrows to indicate the electrons with their spins ( up for clockwise, down for counter clockwise). Squares or lines are used to represent the orbitals and each orbital is labeled.
Carbon atom

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Assignment #4
Orbital Notations

2. The second notation is called electron configuration notation.
Numbers and letters are used to represent the orbitals and raised numbers used to represent the electrons in these orbitals.
Examples
Element(#of electrons)
Notation
H(1)
 1s1
C(6)
 1s2 2s2 2p2
Ti(22)
 1s2 2s2 2p6 3s2 3p6 4s2 3d2

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Assignment #5;
Electron Configuration



3. The third notation is called electron dot or Lewis notation.
This notation use dots placed around the symbol of the element to represent the valence electrons present in the atom.
  • Valence electrons are the electrons in the outermost shell of the atom. These are the electrons most likely to interact when chemical reactions occur and are therefore of great interest to chemists.
  • The # of valence electrons equals the value of the roman numerals found above each column of elements in the periodic table.
  • Electron dots are typically not done on elements in the lanthanide and actinide series.
Electrons are placed around the symbol in a counterclockwise fashion.
 
6th
2nd
  
3rd
Symbol
5th
7th
1st
 
4th
8th
  

electron dot notation
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examples of electron dot notation

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Assignment # 6
Electron Dots