Learning Goal #2 Notes: Bond Comparison
The type of bond can usually be calculated by finding the difference in electronegativity of
the two atoms that are going together.
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If the difference in electronegativities is between:
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1.7 to 4.0: Ionic
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0.3 to 1.7: Polar Covalent
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0.0 to 0.3: Non-Polar Covalent
Example: NaCl
Na = 0.8, Cl = 3.0
Difference is 2.2, so this is an ionic bond!
IONIC BOND
A Bond formed between two ions by the transfer of electrons. Metal + Nonmetal
Ionic Bond Characteristics
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


One atom gains, one loses electrons.
Produce charged ions in all states.
Electrical attraction between ions of opposite charge.
Between atoms of metals and nonmetals with very
different electronegativity
 Strong Bond but not as strong as a covalent bond.
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Crystalline solid.
Very high melting point.
Soluble in H2O.
Insoluble in nonpolar solvents.
Nonconductor of heat and electricity in solid form.
Conducts electricity in aqueous solutions or when melted.
Examples: NaCl, CaCO3
Learning Goal #2 Notes: Bond Comparison
COVALENT BOND
A bond formed by the sharing of electrons. Nonmetal + Nonmetal
Covalent Bond Characteristics
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
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Between nonmetallic elements of similar electronegativity.
Formed by sharing electron pairs
Stable non-ionizing particles
Strongest bond type
Gas, liquid, or a soft solid at room temperature.
Low melting point and low boiling point. Most are Insoluble in H2O
Soluble in nonpolar solvents.
Nonconductor of heat and electricity.
Nonlustrous
NONPOLAR COVALENT BONDS
When electrons are shared equally
H2 or Cl2
POLAR COVALENT BONDS
When electrons are shared but shared unequally
OH-
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Equal distribution of charge
around a central atom.
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Molecule has a symmetrical
shape
Electrons are shared, but not
equally.
Some atoms have a stronger pull
for the electrons.
Molecule not symmetrical in
shape (unbalanced).
METALLIC BOND
A bond found in metals; holds metal atoms together very strongly. Metal + Metal
Metallic Bond Characteristics
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Formed between atoms of metallic
elements
Electron cloud around atoms
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In metals, valence electrons are
shared, free to move about.
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Good conductors of heat and electricity
in all states.
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Strong bond, but weakest of the three
bond types.
Malleable solid
High melting point and boiling point.
Insoluble in H2O.
Insoluble in nonpolar solvents.
Lustrous
Examples: gold, copper