Question

Which of the elements vanadium, chromium, and manganese is most likely to form an oxide with the formula \(\mathrm{MO}_{3}\) ? Explain your answer.

Short answer

Chromium is most likely to form the oxide \(\mathrm{MO}_{3}\), as it commonly exists in the +6 oxidation state required for the oxide formula.

Step-by-step solution

Determine the Oxidation States

To form an oxide with the formula \(\mathrm{MO}_{3}\), the metal \(M\) would need to have an oxidation state of +6 because oxygen typically has an oxidation state of -2. The overall charge of the compound should be zero, so if there are three oxygen atoms each with a charge of -2, the metal \(M\) must balance this with a +6 charge.

Compare the Common Oxidation States

Review the common oxidation states for vanadium, chromium, and manganese. Vanadium typically forms compounds in oxidation states of +2, +3, +4, and +5. Chromium has known oxidation states of +2, +3, and +6. Manganese is commonly found in oxidation states of +2, +3, +4, +6, and +7.

Identify the Element

Since the oxide has a formula of \(\mathrm{MO}_{3}\) and requires the metal to have a +6 oxidation state, chromium is the most likely element to form this oxide, as Chromium (VI) oxide or chromate, \(\mathrm{CrO}_{3}\), is a known compound whereas vanadium and manganese do not commonly form \(\mathrm{MO}_{3}\) oxides.

Key concepts

Chemical Oxidation States

Understanding chemical oxidation states is fundamental in predicting the behavior and properties of elements in compounds. It's the 'accounting method' chemists use to keep track of electrons during chemical reactions. An oxidation state is a positive or negative number that indicates how many electrons an element has gained, lost, or appears to have when it forms chemical bonds with other elements.

In our context with the oxide formula \(\mathrm{MO}_{3}\), the \(M\) represents the metal that needs to have a +6 oxidation state to balance the -2 oxidation state of each oxygen atom. When counting the oxidation state for oxygen, which is usually -2, and you have three oxygens, you would expect the metal to have a +6 charge to achieve a neutral overall charge for the compound. It's this balance that is at the heart of understanding chemical reactions and ultimately, compound stability. For example, chromium in the \(\mathrm{CrO}_{3}\) adopts a +6 oxidation state to align with the charges of the oxygen atoms, creating a stable compound.

Transition Metal Chemistry

Transition metals like vanadium, chromium, and manganese have unique properties that arise from their d electrons. These metals can exhibit multiple oxidation states because they can lose various numbers of electrons from their outer shells. This versatility makes transition metal chemistry intricate and fascinating.

For instance, chromium, the central player in our exercise, is known to exhibit a wide range of oxidation states, with +6 being one of them. This ability to exhibit a +6 oxidation state enables it to form chromium trioxide or chromate (\(\mathrm{CrO}_{3}\)), which is not commonly seen in vanadium or manganese. Understanding transition metals often involves looking at their electron configurations and the different ways they can bond with other elements. To grasp the complexity, students must recognize that the creation of certain compounds depends heavily on an element's ability to adopt the fitting oxidation state.

Chemical Compounds Formulae

When working with chemical compounds, knowing how to write and interpret their formulae is essential. A chemical compound's formula provides a lot of information about the substance, including the elements that make up the compound and the ratios in which they are combined.

In our exercise, the formula \(\mathrm{MO}_{3}\) implies a ratio of one metal to three oxygen atoms. This simplistic view can be misleading unless paired with knowledge about the potential oxidation states of the metal involved. A compound's stability can often be predicted by understanding the common oxidation states of its constituents, as seen in this case with chromium being able to form \(\mathrm{CrO}_{3}\) due to its +6 oxidation state capability. This ties back into knowing how to decipher a compound's formula and predict possible compounds, an invaluable skill in chemistry.