Question

In case of the oxygen family (group 16) (a) the tendency for catenation decreases markedly as we go down the group (b) maximum coordination of oxygen is four due to lack of d orbital, but that of other elements is six due to presence of d orbitals (c) the tendency to form multiple bonds with \(\mathrm{C}, \mathrm{N}\) and \(O\) decreases as going down the group from \(S\) to Te (d) all are correct

Short answer

(d) All are correct.

Step-by-step solution

Understand Catenation in Group 16

Catenation is the ability of an element to form bonds with itself, creating chains or rings. In Group 16, oxygen shows some ability for catenation (e.g., ozone), but this decreases significantly down the group due to the increasing size and decreasing electronegativity of the elements.

Explore Coordination Numbers

Oxygen has a maximum coordination number of four because it lacks d orbitals, which limits its ability to expand its octet. In contrast, other elements in Group 16 like sulfur can have higher coordination numbers (e.g., six), because they have empty d orbitals that can be used for bonding.

Analyze Multiple Bonding with C, N, and O

As we move down the group from sulfur to tellurium, the tendency to form multiple bonds with elements like carbon, nitrogen, and oxygen decreases. This is because the heavier elements have larger atomic sizes and higher energy levels, making them less favorable for forming strong π bonds.

Evaluate Each Option

Option (a): Catenation tendency decreases down the group; true. Option (b): Maximum coordination of oxygen is four and other elements is six due to presence of d orbitals; true. Option (c): Tendency to form multiple bonds decreases down the group; true. All essentially satisfy the properties of Group 16 elements.

Key concepts

Catenation in Oxygen Family

In chemistry, especially when studying the Oxygen Family or Group 16 elements, one encounters the concept of catenation. Catenation refers to an element's ability to form chemical bonds with itself, creating long chains or ring structures. Oxygen, which is part of this family, exhibits some ability for catenation. It forms molecules such as ozone (), where three oxygen atoms link up. However, as we move down the group to elements such as sulfur, selenium, and tellurium, the capacity for catenation decreases markedly.
The primary reason for this decline is the increase in atomic size and a decrease in electronegativity as we go further down the group. Larger atoms tend not to form stable chains or rings as easily because their outer electrons are further from the nucleus, making them less effective at forming stable covalent bonds with themselves.
Some key points regarding catenation in the oxygen family are:

• Oxygen can form small catenated structures (like ozone).
• Heavier Group 16 elements exhibit reduced catenation tendencies.
• This pattern is due to changes in atomic size and electronegativity.

Coordination Number in Group 16

The coordination number of an element refers to the number of other atoms it can bond with. For oxygen, the maximum coordination number is four. This limitation comes from its electronic configuration, where there is no availability of d orbitals to form additional bonds. In simple terms, oxygen can bond with up to four other atoms, but not in the same manner as elements in subsequent periods that can expand their valence shell.
Coordination numbers change as we move to other elements of Group 16, such as sulfur, selenium, and tellurium. These elements have vacant d orbitals, enabling them to form more bonds, thereby having a higher coordination number often reaching up to six. This property allows sulfur, for instance, to create complex molecules such as SF₆.
Let's highlight a few essential points:

• Oxygen's coordination is capped at four due to limits from d orbitals.
• Other Group 16 elements like sulfur can achieve a coordination number of six.
• The presence of vacant d orbitals in heavier elements facilitates this increased coordination.

Multiple Bonding in Oxygen Family

Multiple bonding, particularly  bonding, holds a distinct role within Group 16 elements. In the upper elements, such as oxygen, forming double bonds is common and essential, such as in O₂. Oxygen forms strong and stable  bonds due to its small size and high electronegativity.
However, as we move down the group towards sulfur, selenium, and tellurium, the scenario shifts. These heavier elements find it more challenging to establish multiple bonds. The reason involves several factors:

• Larger atomic size: Larger atoms have a more spread out electron cloud, thus weaker overlap for  bonding.
• Lower electronegativity: Less pull on electrons means weaker  bonds with  overlap.

This shift means that while sulfur sometimes forms  bonds, it does so less commonly than oxygen, and tellurium even less. The practical implications are significant, especially in organic chemistry and the formation of chemical compounds where multiple bonds play crucial roles.
The main takeaways regarding multiple bonding in the oxygen family include:

• Oxygen readily forms strong  bonds.
• The ability for multiple bonds diminishes as you go from sulfur to tellurium.
• A combination of increased atomic size and reduced electronegativity is responsible for this trend.