Which pair of characteristics describes
the molecule shown in the
accompanying illustration?
A.) symmetrical and polar
B.) symmetrical and nonpolar
C.) asymmetrical and polar
D.) asymmetrical and nonpolar
Which electron-dot structure
represents a nonpolar molecule?
Symmetric
Which formula represents a polar
molecule?
A.) Cl2 C.) CH4
B.) CO2 D.) NH3
Properties of Molecules
(think candle wax)
•  Phase depends on the forces of attraction
between molecules
•  Solids are soft (not brittle)
•  Poor conductors of heat and electricity
•  Low melting and boiling points
Which characteristic is a property of
molecular substances?
A.) good heat conductivity
B.) good electrical conductivity
C.) low melting point
D.) high melting point
Polyatomic Ions
•  Covalently bonded atoms with a net charge
•  Polyatomic ions form ionic bonds with another
ion when bonding
•  A compound that contains a polyatomic ion
contains both covalent and ionic bonds!
– Ex: CaCO3
+2
[Ca]
Metallic Bonding
•  Occurs in metals
•  Most metals have only 1 or 2 valence electrons
and low ionization energies
•  Metals are like positive ions surrounded by freely
moving (delocalized) electrons
“Sea of mobile electrons”
•  Alloy – a mixture of metals (ex: brass, bronze,
and steel)
Properties of Metals
•  Good conductor of heat and electricity (due to
freely moving electrons)
•  Ductile and Malleable
•  Luster
•  Variable melting & boiling points
Which substance contains metallic
bonds?
A.) Hg(l)
B.) H2O(l)
C.) NaCl(s)
D.) C6H12O6(s)
Conductivity in a metal results from the
metal atoms having
A.) high electronegativity
B.) high ionization energy
C.) highly mobile protons in the nucleus
D.) highly mobile electrons in the valence shell
Cumulative Bonding Quiz
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• 
• 
• 
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What is going on with the electrons?
What types of elements are involved?
What are they called?
Properties
Drawings (Ionic and Covalent)
–  Molecule polarity for covalent bonds