Why is Mo(II)nitride = MoN3 and not M02N3

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Why is PbO2 not Pb2O4

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For Mo2N3 N would need to be -2 oxidation state and that is highly unlikely. N has usual oxidation states of -3, +3, and +5. Mo has several including 2,3,4,5, and 6.

For PbO2, we usually write the empirical formula unless there is evidence that it exists in some other form; i.e., HO is the empirical formula for hydrogen peroxide BUT we know it exists as H2O2 and we write it the way it exists.

The chemical formula of a compound is determined by the valence (oxidation) numbers of the elements involved.

For Mo(II) nitride, the valence number of molybdenum (Mo) in this compound is +2. Nitrogen (N) typically has a valence number of -3. To balance the charges, the ratio of molybdenum to nitrogen should be 1:3. Therefore, the correct chemical formula for Mo(II) nitride is MoN3.

As for PbO2, the valence number of lead (Pb) in this compound is +4. Oxygen (O) typically has a valence number of -2. To balance the charges, the ratio of lead to oxygen should be 1:2. Therefore, the correct chemical formula for lead dioxide is PbO2, not Pb2O4.

To understand why the formulas for Mo(II)nitride and PbO2 are not M02N3 and Pb2O4 respectively, we need to consider the valency of the elements involved.

For Mo(II)nitride:
- Molybdenum (Mo) has a valency of +2 (as indicated by II in Mo(II)). This means that it tends to lose two electrons to achieve a stable configuration.
- Nitrogen (N) has a valency of -3, meaning it tends to gain three electrons.

To form an electrically neutral compound, the total positive charge from Mo needs to balance the total negative charge from the three N atoms.

Since Mo has a valency of +2, it loses two electrons, resulting in a 2+ charge. On the other hand, each N atom gains three electrons, giving each of them a 3- charge. Therefore, the ratio of Mo to N atoms in the compound needs to be 2:3, balancing the charges.

Hence, the correct formula for Mo(II)nitride is MoN3.

For PbO2:
- Lead (Pb) has a valency of +4.
- Oxygen (O) has a valency of -2.

Similar to the previous case, for PbO2 to be electrically neutral, the total positive charge from Pb must balance the total negative charge from the two O atoms.

Since Pb has a valency of +4, it loses four electrons, resulting in a 4+ charge. On the other hand, each O atom gains two electrons, giving each of them a 2- charge. Thus, to achieve charge balance, there should be two O atoms for every Pb atom.

Therefore, the formula for PbO2 remains as PbO2, not Pb2O4.

In summary, the formulas of chemical compounds are determined by the valencies of the elements involved and the requirement to achieve charge neutrality.