IONIC AND COVALENT
BONDS
8th Grade Science
Case Study: The Hindenburg
Myth Buster’s Mini Myth: http://dsc.discovery.com/tvshows/mythbusters/videos/hindenburg-minimyth.htm
Blimps now use Helium instead of Hydrogen. Why?
Case Study: Hydrogen
What do you notice about Hydrogen?
Case Study: Hydrogen
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Most abundant chemical substance
Colorless, odorless, tasteless, non-toxic, highly
combustible gas
Very high chemical reaction
 Why?
 It
only has one valence electron
 Readily combines and forms Covalent Bonds
Case Study: Noble Gases
What do you notice about the Noble Gases?
Case Study: Noble Gases
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He, Ne, Ar, Kr, Xe, Rn
Odorless, colorless, gases
Very low chemical reactivity
 Why?
 Their
outer shell of valence electrons are considered “full”
 Gives little tendency to participate in chemical reactions
Case Study Conclusion
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Stable-Atoms are “happy” when they have full
energy levels.
Having an uneven amount of valence electrons
causes atoms to react with one another.
Octet Rule: atoms will combine with each other in
order to have eight valence electrons like a noble
gas.
Ions
What compound is being pictured ?
Ions
Infer what has happened in these diagrams:
Review: Ions
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Ions have a charge
Cation: loses an electron
 Positive

charge
Anion: gains an electron
 Negative
 Which
charge
element is a cation? Which is an Anion?
Ionic Bonds- Loss or Gain
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Ionic Bonds: the bonds that hold ions together
Compound: a pure substance containing two or
more elements
Ionic Bonds- Loss or Gain

Infer what has happened in this picture
Ionic Bonds- Loss or Gain

Infer what has happened in this picture
Compounds can be created many ways by losing more
then one electron or gaining more then one electron.
Covalent Bonds- Sharing

Certain atoms cannot lose or gain electrons,
because it is to difficult and takes so much energy.
Covalent Bonds- Sharing
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Covalent Bond- the chemical bond that forms
between nonmetal atoms when they share electrons
The shared electrons are attracted to the nuclei of
both atoms
Covalently bonded compounds are called molecule
compounds.
Molecule: a neutral particle formed when atoms
share electrons
Covalent Bonds- Sharing

Why aren’t ions being formed?
Covalent Bonds- Sharing
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Double Bond: when two pairs of electrons are
shared
Triple Bond: when three pairs of electrons are
shared
Periodic Table Trend
• Covalent Bond is when two non-metals bond together.
• Ionic Bond is when a metal and a non-metal bond together.
Covalent Bonds- Sharing
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Double Bond: when two pairs of electrons are
shared
Triple Bond: when three pairs of electrons are
shared
Chemical Formulas

Chemicals are represented by letters
 Some
symbols are the first letter of their name
 Some symbols are the first letters of their name in
another language
 Potassium
is K, in latin potassium is kalium
 Compounds
 the
subscript illustrates how many atoms are in the molecule
 Chemical
a
are shown using symbols and numbers
formula:
mathematical sequence that expresses a chemical reaction
 Combination of chemical symbols and numbers that show
which elements are present in a compound