Why are electrons important? Electrons are responsible for HOW ELEMENTS REACT That is why we learned how to: – Write electron configurations – Draw electron.
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Why are electrons important?
• Electrons are responsible for HOW ELEMENTS REACT
• That is why we learned how to:–Write electron configurations–Draw electron orbital diagrams
• When we understand electrons–we can predict how elements will behave
(what we can do with them)–Understand the structure of the periodic table
Valence Electrons
• The specific electrons responsible for the chemical properties of an element
• Electrons in an atoms outermost orbitals
• They are in the highest energy levels
Valence Electrons
• Identify number of valence electrons using…–Electron Shell Diagrams–Electron Configurations–Periodic Table
Electron Shell Diagrams
Electron Shell Diagram
Element Symbol F Cl Br I# Protons
# Total Electrons
# Valence Electrons
997
17177
35357
53537
Electron Shell Diagrams• Rules–Draw the nucleus (label
number of protons)–Determine number of
total electrons–The 1st shell can only hold
2 electrons–The 2nd and 3rd shells can
only hold 8 electrons
9
Fluorine9 protons9 electrons
Electron Shell Diagrams
Electron Shell Diagram
Element Symbol B# Protons
# Total Electrons
# Valence Electrons
5
553
Electron Shell Diagrams
Electron Shell Diagram
Element Symbol C# Protons
# Total Electrons
# Valence Electrons
6
664
Electron Shell Diagrams
Electron Shell Diagram
Element Symbol N# Protons
# Total Electrons
# Valence Electrons
7
775
Electron Shell Diagrams
Electron Shell Diagram
Element Symbol O# Protons
# Total Electrons
# Valence Electrons
8
886
Electron Configuration
1. Write the electron configurationO 1s2 2s2 2p4
2. Circle the subshells in the highest energy levels
O 1s2 2s2 2p4
3. Count the electrons in those orbitalsO 1s2 2s2 2p4
2 4+ = 6
O
Electron ConfigurationElement Symbol Electron Configuration # Total
Electrons# Valence Electrons
Li 1s2 2s1 3 1Be 1s2 2s2 4 2Si 1s2 2s2 2p6 3s2 3p2 14 4
Na 1s2 2s2 2p6 3s1 11 1
Al 1s2 2s2 2p6 3s2 3p1 13 3
S 1s2 2s2 2p6 3s2 3p4 16 6
Periodic Table
7777
3 4 5 61 2
41 3 6
The number of valence electrons is the same for all
elements in a group (column).
Lewis Dot Structures
1.Determine the _______________
_______________________ for
the element.
2.Write the element’s ___________.
number ofvalence electrons
symbol
Lewis Dot Structures
3. Draw _____________________ around the symbol.a. Add a _______ _ dot to the _______ side
of the symbol.b. Continue adding _________ dots
_____________ around the symbol.c. Pair up dots only when _______________
of the symbol has a single dot.
valence electrons
single right
singleclockwise
all 4 sides
Lewis Dot Structures
1. Determine the number of valence electrons for the element.
2. Write the element’s symbol.
3. Draw valence electrons around the symbol.
Mg
Magnesium2 valence electrons
Lewis Dot Structures
1. Determine the number of valence electrons for the element.
2. Write the element’s symbol.
3. Draw valence electrons around the symbol.
Cl
Chlorine7 valence electrons
Element Lithium
# Valence electrons 1
Lewis dot structure Li
Lewis Dot Structures
Element Magnesium
# Valence electrons 2
Lewis dot structure Mg
Lewis Dot Structures
Element Boron
# Valence electrons 3
Lewis dot structure B
Lewis Dot Structures
Element Silicon
# Valence electrons 4
Lewis dot structure Si
Lewis Dot Structures
Element Nitrogen
# Valence electrons 5
Lewis dot structure N
Lewis Dot Structures
Element Oxygen
# Valence electrons 6
Lewis dot structure O
Lewis Dot Structures
Element Chlorine
# Valence electrons 7
Lewis dot structure Cl
Lewis Dot Structures
Element Neon
# Valence electrons 8
Lewis dot structure Ne
Lewis Dot Structures
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