Lecture 9 February 4, 2019
Lewis Structures
Hybrid Orbitals
Shapes of Molecules (Common
Stereochemistries in Main Group
Compounds)
,Two Electrons Shared between Two Atoms
Make a Bond! G.N. Lewis
(G. = Gilbert
N. = Newton
Lewis as in Lewis Structures!)
Lewis Structures and VSEPR:
Workshop Study
Simple Review videos
https://www.youtube.com/watch?v=1ZlnzyHahvo
https://www.youtube.com/watch?v=xNYiB_2u8J4
, Rules for Oxidation State Assignment
Rule 1: The oxidation number of an element in its free (uncombined) state is zero —
for example, Al(s) or Zn(s). This is also true for elements found in nature as diatomic (two‐atom) elem
and for sulfur, found as:
Rule 2: The oxidation number of a monatomic (one‐atom) ion is the same as the charge on the ion
Rule 3: The sum of all oxidation numbers in a neutral compound is zero. The sum of all oxidation
numbers in a polyatomic (many‐atom) ion is equal to the charge on the ion
that may have multiple oxidation states, if the other atoms in the ion have known oxidation numbers.
Rule 4: The oxidation number of an alkali metal (IA family) in a compound is +1;
the oxidation number of an alkaline earth metal (IIA family) in a compound is +2.
Rule 5: The oxidation number of oxygen in a compound is usually –2. If, however, the oxygen
is in a class of compounds called peroxides (for example, hydrogen peroxide),
then the oxygen has an oxidation number of –1.
Rule 6: The oxidation state of hydrogen in a compound is usually +1.
If the hydrogen is part of a binary metal hydride (compound of hydrogen and some metal),
then the oxidation state of hydrogen is –1.
Rule 7: The oxidation number of fluorine is always –1.
Chlorine, bromine, and iodine usually have an oxidation number of –1,
unless they’re in combination with an oxygen or fluorine.
Lewis Structures
Hybrid Orbitals
Shapes of Molecules (Common
Stereochemistries in Main Group
Compounds)
,Two Electrons Shared between Two Atoms
Make a Bond! G.N. Lewis
(G. = Gilbert
N. = Newton
Lewis as in Lewis Structures!)
Lewis Structures and VSEPR:
Workshop Study
Simple Review videos
https://www.youtube.com/watch?v=1ZlnzyHahvo
https://www.youtube.com/watch?v=xNYiB_2u8J4
, Rules for Oxidation State Assignment
Rule 1: The oxidation number of an element in its free (uncombined) state is zero —
for example, Al(s) or Zn(s). This is also true for elements found in nature as diatomic (two‐atom) elem
and for sulfur, found as:
Rule 2: The oxidation number of a monatomic (one‐atom) ion is the same as the charge on the ion
Rule 3: The sum of all oxidation numbers in a neutral compound is zero. The sum of all oxidation
numbers in a polyatomic (many‐atom) ion is equal to the charge on the ion
that may have multiple oxidation states, if the other atoms in the ion have known oxidation numbers.
Rule 4: The oxidation number of an alkali metal (IA family) in a compound is +1;
the oxidation number of an alkaline earth metal (IIA family) in a compound is +2.
Rule 5: The oxidation number of oxygen in a compound is usually –2. If, however, the oxygen
is in a class of compounds called peroxides (for example, hydrogen peroxide),
then the oxygen has an oxidation number of –1.
Rule 6: The oxidation state of hydrogen in a compound is usually +1.
If the hydrogen is part of a binary metal hydride (compound of hydrogen and some metal),
then the oxidation state of hydrogen is –1.
Rule 7: The oxidation number of fluorine is always –1.
Chlorine, bromine, and iodine usually have an oxidation number of –1,
unless they’re in combination with an oxygen or fluorine.
