Assign oxidation states for all atoms in each of the...

Assign oxidation states for all atoms in each of the following compounds. a. $\mathrm{UO}_{2}^{2+} \quad \quad f. \mathrm{Mg}_{2} \mathrm{P}_{2} \mathrm{O}_{7}$ b. $\mathrm{As}_{2} \mathrm{O}_{3} \quad \quad g. \mathrm{Na}_{2} \mathrm{P}_{2} \mathrm{O}_{3}$ c. $\mathrm{NaBiO}_{3} \quad h. \mathrm{Hg}_{2} \mathrm{Cl}_{2}$ d. $\mathrm{As}_{4} \quad\quad \quad i. \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}$ e. $\mathrm{HAsO}_{2}$

Assign oxidation states for all atoms in each of the following compounds.
a. $\mathrm{UO}_{2}^{2+} \quad \quad f. \mathrm{Mg}_{2} \mathrm{P}_{2} \mathrm{O}_{7}$
b. $\mathrm{As}_{2} \mathrm{O}_{3} \quad \quad g. \mathrm{Na}_{2} \mathrm{P}_{2} \mathrm{O}_{3}$
c. $\mathrm{NaBiO}_{3} \quad h. \mathrm{Hg}_{2} \mathrm{Cl}_{2}$
d. $\mathrm{As}_{4} \quad\quad \quad i. \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}$
e. $\mathrm{HAsO}_{2}$

Key Concepts

Oxidation States

Oxidation states are theoretical charges assigned to atoms in molecules or ions based on an assumed complete transfer of electrons. They are crucial for understanding electron flow in chemical reactions and for balancing redox reactions, even though the actual electron distribution in bonds is often more complex.

Rules for Assigning Oxidation States

A set of systematic rules is used to assign oxidation states, including common assignments such as oxygen usually being -2, hydrogen +1 when bonded to nonmetals, and the oxidation state of any element in its pure form being 0. These rules ensure consistency when calculating the overall charge of compounds and ions.

Charge Balance Principle

This principle states that the sum of the oxidation states of all atoms in a compound or ion must equal the total charge of the compound or ion. It is essential for determining unknown oxidation states, ensuring that the assignments are chemically reasonable.

Polyatomic Ion Structure

Polyatomic ions are charged entities composed of two or more atoms covalently bonded together. When assigning oxidation states in polyatomic ions, one must consider both the individual oxidation state rules for each atom and the overall ionic charge to achieve a balanced structure.

Elemental Form Oxidation States

In any element's free, uncombined state, the oxidation state is defined as zero. This serves as a foundation for measuring changes in oxidation states during chemical reactions, particularly in oxidation-reduction processes.

Transcript

00:01 So in this video, we're going to go over question 46, so question 86 from chapter 4, which asks us to assign oxidation states for all atoms in each of the following compounds.

00:11 So in a, we have uo2 with a plus 2 charge.

00:16 I remember when we have a charge species, when we have an ion, the oxidation states must add to equal that charge.

00:24 So the oxidation state on oxygen is minus 2, when it's bonded to other atoms.

00:37 So we have an oxidation state of minus 2 on oxygen.

00:39 And since we have two of them, that's contributing minus 4 overall, and we have a plus 2 oxidation state overall.

00:48 So we must have a plus 6, because 6 minus 4 would give us plus 2, on our uranium here.

00:58 So uranium has a plus 6 oxidation state in this case.

01:01 In b, we have as2 o3.

01:05 So again, oxygen takes a minus 2 oxidation state, and since there are three of them, overall that's contributing minus 6, which means our as2 must be contributing plus 6, and since there's two of them, that must be plus 3 each.

01:23 So the oxidation state on arsenic in this case is plus 3.

01:27 And c, we have nabi -03.

01:31 So on our oxygen atom, again, we have a an oxidation state of minus two, and that's overall contributing minus six overall.

01:43 And then on our sodium atom, remember, sodium likes to form ionic compounds.

01:49 So it's acting as an ion in this case.

01:53 And the oxidation state on a monotomic ion is just the charge on that ion.

01:59 So we have a plus one oxidation state in this case.

02:02 But what about bismuth? so we have minus 6 and plus 1.

02:08 That means that the oxidation state of bismith must be plus 5.

02:17 So those are the oxidation states per c.

02:20 In d, we have as4.

02:23 And the oxidation state on this is just zero, because when we have elements in their elemental form, so in comparison would be h2 or o2, the oxidation state is just zero.

02:36 In e, we're given haso2.

02:41 So we know that oxygen has an oxidation state of minus 2 when it's bonded to other atoms.

02:46 And when hydrogen is bonded to other atoms, it has an oxidation state of plus 1.

02:51 So we have minus 4 overall from our o2 and plus 1 from our hydrogen.

02:57 So that leaves us with plus 3 on the arsenic.

03:06 In f, we have mg2p2 -o7...

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