Ionic Compounds Containing
Transition Metals (p. 55)
• Transition Metals: Includes Groups 3 to 11
• The number of electrons that a transition metal
atom can lose can vary.
• EX: Iron (Fe) atom can lose either 2 electrons OR 3
electrons forming Fe2+ OR Fe3+ respectively.
• *****When you are working with transition metals,
you will be given the charge or enough information
to determine the charge on the ions
Chemical Bonds
(Molecular Compounds
& Covalent Bonds) Part 2
Textbook Pages: 52-63
Recall Definitions:
• Covalent Bond: The attraction between atoms that
results from the sharing of electrons.
• Molecular Compounds: A chemical compound
that is held together by covalent bonds.
• Polar Covalent Bond: Electrons are shared
unequally. ΔEN = 0.6 to 1.7
• Covalent Bond: Electrons are shared equally.
ΔEN = Equal to or less than 0.5
Formation of Covalent
Bonds
• Only unpaired electrons are likely to participate in
chemical bonds.
• How can you tell if electrons are shared in a bond?
o You find the ΔEN!!!
o Examples:
• Carbon Dioxide: ΔEN = 1.0 (Polar Covalent)
• Water: ΔEN = 1.4 (Polar Covalent)
Rules for Drawing Lewis Structures for
Molecular Compounds
• 1. Determine, from the chemical formula, the number of
atoms of each type of element in the compound. Use
the last digit of the group number from the Periodic
Table to determine the number of valence electrons for
each atom.
• 2. The element that requires the most electrons to
complete its valence is called the central atom. Draw
the Lewis structure for this atom by placing one electron
on each side of the imaginary square enclosing the
central atom before paring up electrons.
•
A) If there is more than one of this type of atom, write them side by side and
bond them together using a line. Bonds form where there are unpaired
electrons.
• 3. Use the unpaired electrons to bond additional atoms
with unpaired electrons to the central atom until a stable
octet is obtained (there are some exceptions that
disobey the octet rule).
Drawing Lewis Structures for Molecular
Compounds
• Draw the Lewis structures for the following
compounds:
o H2
o Water (H2O)
o Carbon Dioxide (CO2)
o Nitrogen gas (N2)
o OF2
o C2H2
Atoms that can Disobey
the Octet Rule
• NOTE: There are some atoms that can disobey the
octet rule.
o This occurs when they are bonded to highly electronegative atoms (i.e., F,
Cl, Br).
o When this happens, they can take more than 8 electrons (i.e., P, N, S) or
less than 8 electrons (i.e., Be, B).
Atoms
Number of electrons and bonds
Be
4 electrons (2 bonds)
B
6 electrons (3 bonds)
P&N
10 electrons (5 bonds)
S
12 electrons (6 bonds)
Drawing Lewis Structure for Molecular
Compounds that Atoms that Disobey Octet Rule
• Draw the Lewis structures for the following
compounds:
o BF3
o SF6
o PCl5
o BeF2