Lesson 2.6
Lewis Dot Structures
and Covalent Bonds
Covalent Nomenclature
1.  Write the name of the more metallic element
first.
2.  Add PREFIXES to all elements.
–  The one exception is that you never use “mono-“
for the first element.
3.  Add –ide as a suffix to the last element only.
Valence Electrons
•  Valence electrons are those electrons in the
highest principle energy level (n).
•  Only the outer electrons are able to react.
•  How many valence e- does phosphorous have?
•  Argon?
Valence Electrons
•  The number of valence e- is the same as the
number for the “A” groups.
Write it
down on
your own
chart!!!
He is the
one
exception.
Valence Electrons
•  How many electrons do most atoms want in
their “valence shell”?
•  The Octet Rule – most atoms strive for 8 e- in
their outer principle energy level.
•  The elements H, He, Li, Be, and B don’t follow
the rule. Why might that be?
Lewis Structures
•  A Lewis Dot Structure is a way to symbolically
represent the valence electrons of atoms.
•  G. N. Lewis discovered the
covalent bond.
•  He also coined the term
“photon”.
Lewis Structures
•  1) Each dot represents one electron.
•  2) Each line represents two shared electrons in
a covalent bond.
Lewis Structures
•  Imagine there is a square around each
element’s symbol.
•  Add dots to each side before doubling up.
Al
S
Lewis Structures
•  Draw magnesium’s Lewis dot structure.
•  Draw phosphorus's Lewis dot structure.
•  Draw krypton’s Lewis dot structure.
Mg
P
Kr
Lewis Structures
Covalent bond
•  The “goal” of atoms in any chemical bond is to
attain “Noble gas configuration” (8 valence e-).
•  Covalent bond – a chemical bond in which two
or more nonmetals share electrons.
Covalent bond
•  How a covalent bond is formed.
Covalent bond
•  Ex: A chlorine molecule, Cl2
•  Each Cl atom wants to gain 1 e- to become
stable.
•  If each atom shares an e- with the other they
effectively have 18 e- like argon.
Covalent Bond
•  Covalent bonds in H2
Covalent Bond
•  Covalent bonds and potential energy
Covalent Bond
Covalent Bond
•  Diatomic Molecules
If you forget, just ask Mrs. HOFBrINCl!
Hydrogen, oxygen, fluorine, bromine, iodine, nitrogen, chlorine