Question

Which one of the following characteristics of the transition metal is associated with their catalytic activity? (a) variable oxidation states (b) colour of hydrated ions (c) paramagnetic behaviour (d) high enthalpy of atomization

Short answer

(a) variable oxidation states.

Step-by-step solution

Understand Catalytic Activity

Catalytic activity refers to a substance's ability to increase the rate of a chemical reaction without being consumed in the process. In transition metals, this property often stems from their electronic properties and the ability to form complex ions.

Analyze Each Option

Let's analyze the options: (a) Variable oxidation states: Transition metals can exist in multiple oxidation states, allowing them to participate in various redox reactions crucial for catalysis. (b) Colour of hydrated ions: This property is more related to the d-d electron transitions and doesn't directly relate to catalytic behavior. (c) Paramagnetic behavior: This is due to unpaired electrons and affects magnetic properties rather than catalytic properties. (d) High enthalpy of atomization: While high atomization enthalpy can indicate strong metal bonds, it doesn't directly correlate with catalytic activity.

Choose the Most Relevant Characteristic

Considering the association with catalytic activity, (a) variable oxidation states stand out because it enables transition metals to easily interchange electrons in redox reactions, a vital aspect of catalysis.

Confirm the Answer

Based on the detailed analysis, the characteristic of transition metals most associated with their catalytic activity is their ability to display variable oxidation states.

Key concepts

Catalytic Activity

Catalytic activity is an important property that allows transition metals to accelerate chemical reactions. This means they can increase the speed of a reaction while remaining unchanged at the end. Such metals act as catalysts through the provision of a surface for reactions or through the formation of intermediates. Transition metals like iron, nickel, and platinum are commonly used as catalysts in industry because of their unique capability to change oxidation states easily, forming temporary bonds with reactants. The electronic structure of transition metals makes them particularly effective at participating in catalysis.
- They can donate and accept electrons efficiently.
- They enable the formation of complex ions.
These properties are crucial, as they can lower the activation energy of reactions, which results in a faster reaction without being consumed.

Variable Oxidation States

Transition metals are known for exhibiting multiple oxidation states. This means they can lose different numbers of electrons and form a variety of ions. For instance, iron can exist as Fe²⁺ or Fe³⁺ under different conditions. This variability is due to the energy levels of the d-orbitals, which are close to each other.

• Facilitates various chemical reactions.
• Enables redox reactions in catalytic processes.

The ability to shift between different oxidation states allows transition metals to engage in electron exchanges effectively. This capability is essential in processes like industrial catalysis, where electrons need to be shuffled back and forth during the chemical transformations.

Redox Reactions

Redox reactions are processes where the oxidation state of atoms changes through the transfer of electrons. Transition metals play a pivotal role in these reactions due to their varied oxidation states. In redox reactions, one species is oxidized (loses electrons) while another is reduced (gains electrons). Transition metals can act as both oxidizing and reducing agents, making them extremely versatile.

• Drive essential biological processes such as photosynthesis and cellular respiration.
• Utilized in synthesizing essential chemicals like ammonia and sulfuric acid.

The flexible electron configurations of transition metals allow them to easily undergo redox transformations, maintaining the balance of oxidation and reduction while facilitating complex chemical reactions.

Transition Metals Properties

Transition metals possess several fundamental properties that contribute to their widespread use and importance in chemistry. These elements are located in the d-block of the periodic table. They are notable for their hardness, high melting and boiling points, and the ability to form colored compounds. Moreover, transition metals exhibit:

• High conductivity due to delocalized electrons.
• Strong metallic bonds providing structure and strength.
• Paramagnetism, resulting from unpaired d electrons.

These shared properties enable transition metals to be used in many applications, including structural materials, electronics, and catalysis. Their diverse chemical and physical properties are due to the unique electron configurations that allow them to interact robustly with other elements.