View source for Lewis electron-dot symbols of elements

Gilbert N. Lewis is widely known for his use of simple symbolic representations of [[Classification of matter#Element|elements]] that show valence [[Subatomic particles|electrons]] as dots. You've seen what the are [[Bohr model of the atom|Bohr diagrams]] for the [[Bohr model of the atom#Bohr diagrams|first 20 elements]]. Sometimes it is more convenient to represent the elements by its '''Lewis electron-dot symbol'''. It is not to say one is better than the other. The Bohr diagrams show arrangement of all the electrons. 

The Lewis electron-dot symbols focus on the electrons in the highest principal energy level in the [[atom]], the valence electrons. After all, these are the electrons that participate in chemical reactions. Lewis electron-dot symbols work well for the representative elements.

==Rules for writing electron-dot symbols of elements==
1. Write the symbol for the element. The symbol represents the nucleus and the inner or core electrons for the element. In the image below, a generic symbol, X, is used. There are four sides surrounding the symbol. 

{| cellpadding="10" 
| <center>[[File:lewis1.gif|link=]]</center>
|-
|}

2. Determine the number of valence electrons for the element. Use a dot to represent an electron.

3. Assign a dot to each side of the symbol up to a '''maximum of four valence electron'''.
{| cellpadding="10" border="1" cellspacing="0"
| <center>[[File:lewis2.gif|link=]]</center>
| <center>[[File:lewis3.gif|link=]]</center>
| <center>[[File:lewis4.gif|link=]]</center>
| <center>[[File:lewis5.gif|link=]]</center>
|-
| 1 valence electron
| 2 valence electrons
| 3 valence electrons
| 4 valence electrons
|-
|}

([[Helium]] is an exception, with both valence electrons paired up on the same side of the symbol.)

4. For assigning more than 4 valence electrons, start pairing up electrons on the four sides to a '''maximum of eight electrons'''. 
{| cellpadding="10" border="1" cellspacing="0"
| <center>[[File:lewis6.gif|link=]]</center>
| <center>[[File:lewis7.gif|link=]]</center>
| <center>[[File:lewis8.gif|link=]]</center>
| <center>[[File:lewis9.gif|link=]]</center>
|-
| 5 valence electron
| 6 valence electrons
| 7 valence electrons
| 8 valence electrons
|-
|}

The number of dots you have around the symbol represents the actual number of valence electrons for the element.

==Representative elements==
{| cellpadding="10" border="1" cellspacing="0"
! Representative Elements in:
! Number of Valence Electrons
|-
| Group IA
| all elements have '''1 valence electron'''
|-
| Group IIA
| all elements have '''2 valence electrons'''
|-
| Group IIIA
| all elements have '''3 valence electrons'''
|-
| Group IVA
| all elements have '''4 valence electrons'''
|-
| Group VA
| all elements have '''5 valence electrons'''
|-
| Group VIA
| all elements have '''6 valence electrons'''
|-
| Group VIIA
| all elements have '''7 valence electrons'''
|-
| Group VIIIA
| all elements have '''8 valence electrons'''
|-
|}

===Symbols===
{| cellpadding="10"
| '''Group IA'''

[[File:lewis2.gif|link=]] 

X = H, Li, Na, K, Rb, Cs, Fr
| '''Group IIA'''

[[File:lewis3.gif|link=]]  

X = Be, Mg, Ca, Sr, Ba, Ra
| The exception is He.

[[File:lewishe.gif|link=]] 

X = He
|-
| '''Group IIIA'''

[[File:lewis4.gif|link=]]

X = B, Al, Ga, In, Tl
| '''Group IVA'''

[[File:lewis5.gif|link=]]

X = C, Si, Ge, Sn, Pb
|-
| '''Group VA'''

[[File:lewis6.gif|link=]]

X = N, P, As, Sb, Bi
| '''Group VIA'''

[[File:lewis7.gif|link=]]

X = O, S, Se, Te, Po
|-
| '''Group VIIA'''

[[File:lewis8.gif|link=]]

X = F, Cl, Br, I, At
| '''Group VIIIA'''

[[File:lewis9.gif|link=]]

X = Ne, Ar, Kr, Xe, Rn
|-
|}


==Content suitability==
BCIT courses:
<span class="pops">[http://www.bcit.ca/study/outlines/chem0011  CHEM 0011]</span>