Unit 3 Test Concepts
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Chemical bond
o Why do bonds form?
o Exothermic
o Electrostatic force
Octet rule
o Exceptions to the octet rule
 Duet-hydrogen and helium
 Pseudo-noble gas configuration
 Transition metals
 Electron deficient atoms (B and Be)
 Expanded octet
Types of chemical bonds
o Electronegativity
Ionic bond
o Cations and anions
o Neutral compounds! Writing molecular formulas for ionic compounds
o Properties of ionic compounds
 Solids at room temperature
 Strong bonds
 High melting point
 Hard, brittle
 Electrolyte, conducts electricity
 Crystal lattice
Energy of ionic bonds
o Lattice (formation) energy
o Lattice (dissociation) energy
o Ionic radius
o Lattice energy and bond strength and melting point
Covalent bonds
o Formation of covalent bonds
o Single, double, triple bond
o Nonpolar v. polar bonds
o Property of covalent bonds
o Energy of covalent bonds: bond dissociation energy
Lewis Structures
o Bonding v. lone pairs
o Remember to follow rules for drawing lewis structures
o Remember exceptions
o Lewis structures for polyatomic ions
Metallic bonds
o Delocalized electrons
o Electron sea model
o Properties of metals
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 Be able to explain properties in terms of metallic bond
 Melting and boiling point
 Malleable and ductile
 Conductors of heat and electricity
 Metallic bond strength
Nomenclature
o Type I, II, and III naming
3-D shape of molecules: VSEPR
o Be able to predict 3-D shape of molecules.
o Memorize shapes, names of shapes, and bond angles through 4 electron
pairs around the central atom.
Polar bonds and polar molecules
o Be able to identify whether a bond will be polar or nonpolar
o Be able to identify whether a molecule will be polar or nonpolar
o Dipole moment