Notes.notebook
October 24, 2011
Exceptions to the Rules
Chromium: [Ar] 4s
[Ar] 4s
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3d 4 is NOT correct.
3d 5 is correct.
Copper is the same way, but they are not alone.....this is due to the increased stability of half­filled and filled sets of s and d orbitals. REMEMBER: electrons want to have the least amount of energy and be as stable as possible.
Oct 20­2:35 PM
Valence Electrons
Remember: its the electrons that determine the chemical behavior of an atom­but really its the electrons.
valence Valence Electrons ­ Ones in atom's outermost orbitals (usually highest principle energy levels)..These are your s and p electrons.
It's easy to determine the ones in the s and p block. Take a look at your periodic table.
Atoms of the same GROUP have similar chemical properties
(e - determines the chemical properties.)
Oct 20­2:40 PM
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Notes.notebook
October 24, 2011
VALENCE ELECTRON WORKSHEET
‐Together
‐Independently
Oct 20­2:47 PM
Because of the important role that valence electrons play in forming chemical bonds we often represent them visually in a structure called Lewis Dot Diagrams or electron dot diagrams.
(Lewis is the last name of the man who devised this method while teaching a college chemistry class in 1902)
­Contain element symbol (stands for nucleus and all inner electrons.)
­Valence electrons are arrranged around the outside
­Treat the symbol as a clock, most important four digits on a clock: ­­­this is where we place the valence electrons.
­each side must get an electron before you start doubling them, order of placement aroudn the symbol doesn't matter.
Oct 20­2:48 PM
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Notes.notebook
October 24, 2011
Examples:
Electron Configurations
Lewis Dot Diagram
Boron:
Fluorine:
Neon:
Homework:
Lewis Dot Diagram Worksheet...Include electron configurations!
Oct 20­2:55 PM
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