Nombre los óxidos siguientes. Suponiendo que los compuestos...

Nombre los óxidos siguientes. Suponiendo que los compuestos sean iónicos, ¿qué carga está asociada al elemento metálico en cada caso? (a) $\mathrm{NiO}$; (b) $\mathrm{MnO}_2$; (c) $\mathrm{Cr}_2 \mathrm{O}_3$; (d) $\mathrm{MoO}_3$.

Key Concepts

Oxidation State Determination

This concept involves assigning oxidation numbers to atoms within a compound based on a set of rules. For ionic compounds, the sum of the oxidation states of all atoms must equal the overall charge of the compound, which is typically zero for neutral compounds. In oxides, oxygen is almost always assigned a ?2 oxidation state, allowing the oxidation state of the metal to be calculated by balancing the overall charge.

Ionic Compound Charge Balance

Understanding that in any ionic compound the total positive and negative charges must cancel out is fundamental. When dealing with metal oxides, the metal’s positive charge must counterbalance the negative charge of oxygen ions. This leads to a straightforward calculation where, for example, if one oxygen has a charge of ?2, the corresponding metal ion’s charge will be +2 in a simple monoxide.

Transition Metal Variable Oxidation States

Many transition metals can exhibit multiple oxidation states. This variability is crucial for correctly determining the specific charge on the metal in a given compound. The stoichiometry of the compound, such as the number of oxygen atoms present, helps indicate which oxidation state the metal has adopted in that particular oxide.

Nomenclature of Metal Oxides

The naming of metal oxides often involves indicating the oxidation state of the metal, especially for transition elements. This can be done using Roman numerals in the compound’s name, ensuring that the chemical identity and the specific ionic charges of the elements involved are clearly communicated.

Transcript

00:01 So when we're naming ionic substances where we have a metallic element that is part of the transition metals, the way we name that is the name of the metal.

00:15 We have a roman numeral, which will be the charge of the metal.

00:23 And then we're going to have the ending with the non -metal, but we change that ending to id.

00:32 D, b.

00:34 So let's take a look at some examples.

00:37 So we have n -i -o.

00:41 So the metal here is n -i, that's nickel.

00:47 We're going to have a roman numeral for the charge of the metal, which we'll get back to in a moment.

00:54 O is oxygen, so when we put the i -d -e ending, that is ox -eyed.

01:01 Now, how do we find the charge of the metal? we know that the sum of the charge has to be zero because it's a neutral substance.

01:12 Oxygen has a charge of negative two.

01:17 So what is the charge of nickel? what minus two is zero? well, two is the charge of nickel because two minus two is zero.

01:25 So it gets a roman numeral two.