Question

The correct sequence of the oxidation state of underlined elements is \(\mathrm{Na}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NO}\right], \mathrm{K}_{2} \mathrm{TaF}_{7}, \mathrm{Mg}_{2} \mathrm{P}_{2} \mathrm{O}_{7}, \mathrm{Na}_{2} \mathrm{~S}_{4} \mathrm{O}_{6}, \mathrm{~N}_{3} \mathrm{H}\) (a) \(+3,+5,+5,+2.5,-\frac{1}{3}\) (b) \(+5,+3,+5,+3,+\frac{1}{3}\)

Short answer

+3, +5, +5, +2.5, -\frac{1}{3}

Step-by-step solution

Determine the oxidation state of Fe in Na2[Fe(CN)5NO]

For the complex \( Na_2[Fe(CN)_5NO] \), the overall charge is 0. The oxidation state of Na is always +1, so for two Na atoms it is +2. CN is a -1 ligand, with 5 CN ligands summing to -5. The charge of NO can be either +1 or +3 typically; but in this complex, it must be +1 to balance the charge, making the Fe have an oxidation state of +3.

Determine the oxidation state of Ta in K2TaF7

In the compound \( K_2TaF_7 \), the overall charge is 0, and the oxidation state of K is always +1, summing to +2 for two K atoms. F has an oxidation state of -1. With 7 F atoms, that's -7. To balance, Ta must have an oxidation state of +5.

Determine the oxidation state of P in Mg2P2O7

The compound \( Mg_2P_2O_7 \) has an overall charge of 0. The oxidation state of Mg is always +2, so for two Mg atoms it is +4. Oxygen has a common oxidation state of -2. With 7 oxygen atoms, this comes to -14. To balance the charge, the total oxidation state of the two P atoms must be +10, so each P atom has an oxidation state of +5.

Determine the oxidation state of S in Na2S4O6

In the compound \( Na_2S_4O_6 \), the overall charge is 0, and the oxidation state of Na is always +1, hence for two Na atoms it is +2. Oxygen has an oxidation state of -2, so for 6 oxygen atoms, the total is -12. To balance, the total oxidation state for four S atoms must be +10. Hence, the average oxidation state of S is +2.5.

Determine the oxidation state of N in N3H

In the compound \( N_3H \), the overall charge is 0. Hydrogen typically has an oxidation state of +1. Therefore, to balance the single hydrogen, the total oxidation state of the three nitrogen atoms together must be -1. This means the average oxidation state of each N atom is -1/3.

Key concepts

Chemical Oxidation Numbers

Understanding chemical oxidation numbers is foundational when studying redox reactions and inorganic compound nomenclature. Oxidation numbers, also referred to as oxidation states, provide important details about the distribution of electrons among the atoms in a compound.

An element's oxidation number is the charge it would have if the compound was composed of ions. For instance, sodium (Na) in a compound almost always has an oxidation number of +1. Meanwhile, oxygen (O) usually has an oxidation number of -2, reflecting their loss or gain of electrons in many compounds.

To determine an element's oxidation state, one should apply several rules:

• The oxidation state of a pure element is always 0.
• The sum of oxidation states in a neutral compound is 0, while in a polyatomic ion it equals the ion's charge.
• Some elements have fixed oxidation states in all their compounds (e.g., Group 1 metals are always +1).
• Fluorine always has an oxidation number of -1 in compounds, as it is the most electronegative element.
• Oxygen usually has an oxidation state of -2, except in peroxides or in combination with fluorine.
• Hydrogen typically has an oxidation number of +1 when bonded with non-metals and -1 when bonded with metals.

Calculating the correct oxidation states involves using these rules to deduce the most likely scenario for electron distribution and is essential for understanding a compound's chemical behavior.

Redox Chemistry

Redox chemistry is the branch of chemistry that studies the changes in the oxidation state of atoms through redox reactions. These reactions include the transfer of electrons between substances. One species will lose electrons and become oxidized, while another will gain electrons and become reduced.

In a redox process, the element that loses electrons increases its oxidation state, indicating oxidation, and the element that gains electrons decreases its oxidation state, indicating reduction. It's essential to remember that redox reactions always involve a change in the oxidation states of the reacting species.

An easy way to remember this is with the mnemonic 'OIL RIG': Oxidation Is Loss, Reduction Is Gain. Recognizing the changes in chemical oxidation numbers can help you identify what is being oxidized and what is being reduced in a reaction. This understanding is also crucial for tasks like balancing redox equations and predicting the outcomes of chemical reactions.

Inorganic Compound Nomenclature

Correct naming of inorganic compounds relies on a set of rules set forth by the International Union of Pure and Applied Chemistry (IUPAC). Inorganic compound nomenclature requires the identification of the elements present and their oxidation states to correctly construct the name of the compound.

For binary compounds, the name typically starts with the cation followed by the anion. For example, in magnesium chloride (MgCl₂), magnesium is the cation with a +2 oxidation state, while chloride is the anion with a -1 oxidation state. Polyatomic compounds often include prefixes and suffixes to indicate the quantity of atoms or the presence of different oxidation states.

• Prefixes like mono-, di-, tri-, are used to denote the number of atoms of a particular element in the compound.
• The suffix -ide usually is added to the anion's name when it's a single element, like in chloride or oxide.
• For elements that can exist in multiple oxidation states, Roman numerals indicate the specific oxidation state, such as in iron(III) oxide for Fe₂O₃.

These naming conventions ensure clarity when communicating chemical information and allow someone knowledgeable in the field to infer certain chemical properties just by knowing the compound's name.