Chemical Bonds
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http://www.youtube.com/watch?v=CGA8s
RwqIFg
Types of Chemical Bonds
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Ionic bonds are the electrostatic forces that
exist between ions of opposite charges
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Ions are formed
electrons are transferred from one atom to
another
Covalent bonds result from the sharing of
one or more electrons between two atoms
Metallic bonds are found in metals
Why do Atoms interact?
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Octet Rule
Atoms tend to gain, lose, or share electrons in
order to attain a noble gas electron
configuration
This configuration is especially stable
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all noble gases, except He, have 8 valence electrons
atoms attaining a noble gas configuration is known
as the octet rule
there are many exceptions to the octet rule but it is
still a useful guideline
Practice—Write the Lewis Symbol for
Arsenic.
1.
Write the atomic symbol for the element
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2.
Determine the number of valence
electrons
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3.
As
As is in column 5A, therefore it has 5 valence
electrons.
Put dots around the atomic symbol one at
a time to represent electrons
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 As 
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4
Lewis Symbols of the Period 2
Elements
Metals Gain Electrons
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Metals lose electrons to be like the
nearest noble gas. (These are the atoms
on the right side of the periodic table).
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The atom that has lost electrons now has
fewer electrons than protons, so it has a
positive charge.
Ions with positive charge are called
“cations.”
Nonmetals Lose Electrons
Nonmetals gain electrons to be like the
nearest noble gas. (These are the atoms
on the left side of the periodic table)
 The atom that has gained electrons now
has more electrons than protons, so it has
a negative charge.
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All atoms that have any charge on them are
called “ions.”
Ions with negative charge are called “anions.”
Forming Compounds
Nonmetals lose electrons to be like the
nearest noble gas. (These are the atoms
on the left side of the periodic table)
 The atom that has gained electrons now
has more electrons than protons, so it has
a negative charge.
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All atoms that have any charge on them are
called “ions.”
Ions with negative charge are called “anions.”
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Sometimes a charge is called the oxidation state.
Writing Ionic Formulas
1. Write the formulas of the cations and
anions next to each other (with charges)
2. Drop and Swap writing with cation first
3. Reduce to smallest ratios
Do not write “1”
Chapter 2/9