Question

The first member of the \(p\)-block elements differs from the remaining members of their corresponding groups due to (a) small size and absence of \(d\)-orbitals (b) diagonal relationship with other elements (c) difference in ability to form double and triple bonds (d) high ionisation enthalpy.

Short answer

The first member of the p-block elements differs from the remaining members of their group due to the small size and absence of d-orbitals, making option (a) correct.

Step-by-step solution

Understanding the P-block elements

The p-block elements are those found in groups 13 to 18 of the periodic table. Their outermost electrons are in p-orbitals. These elements have varied properties and they differ across periods and groups.

Considering the first member differences

The first member of each p-block group has distinct properties from the other elements in the same group. This is largely due to factors such as small size and high electronegativity. Additionally, for groups 13 to 15, the first members do not have accessible d-orbitals in their valence shell, which can influence their chemistry significantly.

Identifying the correct option

The first member of the p-block elements differs mainly due to their small size and absence of d-orbitals in their valence level. This affects their chemical behavior and properties when compared to the remaining members of their groups. Thus, option (a) 'small size and absence of d-orbitals' correctly explains the difference.

Key concepts

Understanding the Periodic Table

The periodic table is a cornerstone of modern chemistry, visually displaying elements in a structured grid that organizes them by atomic number, electron configuration, and recurring chemical properties. Elements are grouped into rows called periods and columns known as groups or families.

Each element's position reflects its atomic structure; specifically, the number of protons in their nucleus and electrons in their outer shell, which informs their chemical behavior. Grouping elements into the p-block, for instance, tells us that their highest energy electrons reside in the p-orbital. Understanding their location in the periodic table aids in predicting how these elements will react chemically, form bonds, and interact with other elements.

Unraveling Chemical Properties of Elements

The chemical properties of elements are intrinsic behaviors observed during chemical reactions. These properties include reactivity, ionization energy, electronegativity, and the ability to form specific types of bonds. For example, elements in the p-block have diverse chemical behaviors:

• Reactivity often increases down the groups, influenced by the additional electron shells that shield the outer electrons from the nucleus.
• Ionization energy tends to decrease as you move down a group but increases across a period, which corresponds to the increase of nuclear charge and the pull it exerts on the valence electrons.
• Electronegativity, the tendency of an atom to attract shared electrons, often follows a similar trend, diminishing down groups while escalating across periods.

These trends in the chemical properties of p-block elements underscore the importance of understanding electron configuration and atomic size when analyzing an element's chemical nature.

Role of d-Orbitals in Chemical Bonding

d-Orbitals play a critical role in the chemistry of transition elements but also subtly influence the chemical properties of certain p-block elements. Elements with accessible d-orbitals in their valence shell can utilize these orbitals to form expanded octets, allowing for the formation of additional bonds.

While the first members of the p-block groups 13 to 15 lack d-orbitals in their valence levels, the subsequent elements (such as Silicon in group 14, compared to Carbon) can utilize d-orbitals for bonding. These differences can influence the elements' ability to participate in multiple bonding scenarios, like double and triple bonds, and their overall reactivity.

Therefore, the absence of d-orbitals in the first member of a p-block group leads to distinct chemical properties compared to their heavier congeners within the same group that do have accessible d-orbitals.