Honors Chem.: Test Objectives Covalent & Metallic Bonding
Name: _________________________________________________________
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Date: ______
Define the term chemical bond.
Recognize that atoms attain a stable valence electron configuration by bonding with
other atoms. Noble gases have stable valence electron configurations (full octets) and
tend not to bond.
In covalent bonds, atoms achieve a noble gas configuration by sharing electrons with
other atoms. A covalent bond occurs when the electrostatic forces of attraction between
two nuclei and their shared electrons is greater than the repulsive forces between the two
compounds.
In a single covalent bond, one pair of electrons is shared nuclei and between the
electrons.
Know the procedure for drawing Lewis Dot Diagrams for covalent
o between atoms.
o In a multiple covalent bond, more than one pair of electrons is shared between
two atoms.
 Double bond: two pairs of electrons are shared.
 Triple bond: three pairs of electrons are shared.
o Explain why resonance structures are used to represent some molecules.
o Strength: Triple > double > single…. Length: single > double > single
Understand why when a bond is broken, energy is absorbed; when a bond is made,
energy is released.
Understand the relationship between energy and stability. (As energy , stability.)
Define the term ionic bond and list the properties of ionic substances.
Define the term covalent bond and list the properties of covalent substances.
o Most covalent substances are molecular.
o A few covalent substances are network.
o Understand the differences in structure that lead to such different properties for
molecular and network substances.
Define the term metallic bond and list the properties of metallic substances. Understand
the term “sea of mobile electrons.” Loosely held outer electrons are shared by all metal
atoms
Metals have a crystal lattice formed from cations. Ionic compounds have a crystal lattice
formed from both cations and anions. Most covalent compounds form molecules.
Identify the type of bonding in a substance from its chemical formula.
Remember that ionic bonds form units called formula units and covalent bonds make
units called molecules.
Identify the type of bonding in a substance from its physical properties.
Understand the relationship between structure and properties for each type of compound.
Use electronegativity differences to distinguish between covalent and ionic bonds: nonpolar covalent bonds (EN difference of 0 to ≤ 0.4), polar covalent bonds (EN
difference of > 0.5 to ≤ 2.0), and ionic bonds (EN difference > 2.0 . Understand that
most chemical bonding is neither purely ionic nor purely covalent.
o The higher the electronegativity differences between two atoms, the greater the
ionic character of the bond (or the lower the covalent character).
o The lower the electronegativity difference, the greater the covalent character of
the bond (or the lower the ionic character).
Use VSEPR theory to predict 3-D shapes of simple molecules and ions from the Lewis
structure. Know the names of the shapes (e.g. linear, bent, trigonal pyramidal,
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trigonal planar, and tetrahedral, trigonal bypyramidal, see saw, T-Shape,
octahedral, square pyramidal, square planar).
Predict the polarity of a molecule by using its shape + its bond polarities.
o Some shapes are so asymmetric, they are always polar: bent & pyramidal, i.e..
o Linear molecules will be nonpolar if the ends are the same.
o Tetrahedral molecules will be nonpolar if all four corners are the same.
o Larger molecules, such as hydrocarbon molecules, CxHy, are also symmetric and
nonpolar.
Understand that polar molecules have a “lop-sided” or asymmetric electron cloud, with
separation of charge.
For covalently bonded compounds, given the formula, predict which of three
intermolecular forces will be most important:
o London dispersion or Van der Waals forces – between nonpolar molecules
o Dipole-dipole forces – between polar molecules
o Hydrogen bonding – between molecules containing an H-F, H-O, or H-N bond.
Explain physical properties of substances in terms of chemical bonds and intermolecular
forces. These properties include conductivity, malleability, solubility, hardness,
melting point, boiling point.
Recognize that the chemistry of water is directly related to its bond type. Water has polar
covalent bonds in a bent shape. So the water molecule has a whole is polar. The oxygen
end has a partial negative charge and the two protons each have a partial positive charge.
Recognize molecular formulas of polyatomic ions. Be able to draw Lewis structures for
compounds containing polyatomic ions.
Know the order of IMFs. From weakest to strongest: London, dipole-dipole, hydrogen
bonding, ionic, covalent network (metallic is somewhere in between most of these)
Know that some compounds that have double and or triple bonds can have
RESONANCE. This means that they can have more than one structure that is legitimate
for the compound. Remember that there isn’t really more than one structure, but there is
an intermediate structure that is shorter than the single bonds in the molecule, but longer
than the multiple bonds in the molecule.
Realize that most single bonds are sigma bonds and ALL double and triple bonds contain
at least one pi bond. Make sure you know the difference on how they form.
o End to end overlaps are sigma bonds
o Side to side overlaps are pi bonds. They look like two bonds, but are only one
bond.
o Single-doubletriple