Question

Which group element of d-block do not form hydride at all? (a) 7 (b) 9 (c) 8 (d) All of these

Short answer

Group 8 and Group 9 d-block elements do not form hydrides.

Step-by-step solution

Understand D-block Elements

The d-block elements are also known as transition metals and are located in groups 3 through 12 of the periodic table. These elements are characterized by having d-electrons, which can be important for bonding and forming compounds.

Define Hydrides

Hydrides are compounds formed when hydrogen is bonded to other elements. Transition metals can form hydrides when they react with hydrogen under certain conditions, typically with low oxidation states or when they can accommodate the hydrogen atom within their structure.

Review Group 7 Elements

Group 7 of the d-block elements includes manganese (Mn) and they can generally form hydrides, though it may be rare or unstable.

Review Group 8 Elements

Group 8 elements include iron (Fe), ruthenium (Ru), and osmium (Os). These elements do not readily form stable hydrides due to their electronic configurations and bonding capacities.

Review Group 9 Elements

Group 9 contains cobalt (Co), rhodium (Rh), and iridium (Ir). Similar to Group 8, these elements also do not typically form stable hydrides because of unfavorable electronic configurations or the metal's inability to stabilize the hydrogen atom as a hydride.

Conclusion

Elements in Group 8 and Group 9 of the d-block generally do not form hydrides. Therefore, Groups 8 and 9 are both correct answers to the question, meaning multiple or all groups may be the right answer.

Key concepts

Hydride Formation

Hydrides are chemical compounds that contain hydrogen bonded to another element. In the case of the d-block elements, forming hydrides typically requires specific conditions. These compounds are formed when hydrogen gets attached to a metal, often in a way where the hydrogen ion (H\(^-\)) can fit into the metal's electron cloud. It’s important to note that hydrides can vary in stability, and not all metal hydride bonds are easily formed or maintained. Transition metals usually form hydrides when they are in low oxidation states or when their structural configuration allows them to accommodate hydrogen. This means not all transition metals readily form hydrides, largely due to the unique structure and chemistry of each metal element in the d-block.

Transition Metals

Transition metals are a distinctive group of elements located in the center of the periodic table, spanning groups 3 to 12. These elements are known as transition metals because they are the 'bridge' for transitioning from highly reactive metals to less reactive nonmetals. One of their defining features is the presence of partially filled d-electron sublevels. This often grants them interesting properties such as the ability to form various oxidation states, colored compounds, and complex ions. Because of their versatile electronic structures, these metals play crucial roles in catalysis and industrial processes. However, this versatility does not universally extend to forming hydrides, as some transitions metals, due to their electron configuration, cannot easily stabilize hydrides.

Periodic Table Groups

The periodic table is organized into groups and periods, offering a systematic arrangement of elements according to increasing atomic number. The groups, labeled from 1 to 18, categorize elements with similar properties and valence electron configurations. In the d-block, the elements are sorted into groups 3 through 12. Each group harbors unique characteristics, which also affect how these elements interact with hydrogen to form hydrides. Group 7 contains manganese, known to form rare or unstable hydrides. Groups 8 and 9 include elements like iron, cobalt, and rhodium, which generally do not form stable hydrides, illustrating how even small differences in electronic structure can influence chemical behavior.

Bonding with Hydrogen

The bonding between hydrogen and transition metals can lead to the formation of hydrides, but whether such bonds are stable or even feasible depends on many factors. Hydrogen is unique because it can act like both a proton (H\(^+\)) and a hydride ion (H\(^-\)), allowing it to form various types of bonds. In the context of transition metals,

• Stability: The electronic structure of the metal largely dictates if a stable hydride can form.
• Oxidation state: Metals in low oxidation states are more likely to form stable hydrides.
• Electron density: The ability to stabilize the additional electron density of hydrogen is crucial.

These factors mean that while some transition metals can indeed bond with hydrogen to form hydrides, others do not, due to their electronic and structural limitations. This nuanced interaction underscores why understanding each metal's inherent properties is imperative to predicting hydride formation.