Question

Select the member of group 14 that best fits each description: \((\mathbf{a})\) has the greatest tendency to form multiple bonds with itself, (b) forms polymeric structures with oxygen, (c) is a metal with +2 and +4 oxidation states.

Short answer

(a) Carbon (C) has the greatest tendency to form multiple bonds with itself due to its small atomic size and high electronegativity. (b) Silicon (Si) forms polymeric structures with oxygen, such as silicon dioxide (SiO₂). (c) Lead (Pb) is a metal with +2 and +4 oxidation states, commonly exhibiting both states.

Step-by-step solution

Understanding the properties of Group 14 elements

Group 14 elements usually have an oxidation state of +4 due to their four valence electrons. However, they can also form +2 oxidation states. Generally, as we move from carbon to lead in Group 14, the metallic character of the elements increases, and the covalent bonding nature decreases. Now, we can identify which element best fits each description.

Identifying the element with the greatest tendency to form multiple bonds with itself

Among the group 14 elements, carbon (C) has the smallest atomic size and the highest electronegativity. Due to its small size, it can form strong covalent bonds with other carbon atoms by sharing its electrons. This leads to multiple bonds like double and triple bonds. Therefore, carbon best fits the description for (a).

Identifying the element that forms polymeric structures with oxygen

Silicon (Si) readily forms strong covalent bonds with oxygen to create polymeric structures. One of the most common structures is silicon dioxide (SiO₂), which forms a network of Si-O covalent bonds. Considering silicon's ability to form polymeric structures with oxygen, it best fits the description for (b).

Identifying the metallic element with +2 and +4 oxidation states

Tin (Sn) and lead (Pb) are the most metallic elements in Group 14, and both can form +2 and +4 oxidation states. However, lead is widely known to be a metal that more commonly exhibits a +2 oxidation state in addition to its +4 oxidation state. Therefore, lead is the element that best fits the description for (c).

Key concepts

Oxidation States

In chemistry, oxidation states help us understand how electrons are distributed in a compound. For Group 14 elements, these states mainly range between +4 and +2.

Each element in this group has four valence electrons, which they can use for bonding. Usually, they try to reach an oxidation state of +4 by sharing or transferring these electrons.

• Carbon often displays an oxidation state of +4, particularly in compounds like carbon dioxide. However, it rarely shows a +2 oxidation state because of its strong ability to form multiple bonds.
• Silicon, tin, and lead also enjoy the +4 state, but as you move down the group, the +2 state becomes more common. This is due to the inert pair effect, where the s-orbitals are less reactive.”
• Lead most frequently exhibits the +2 oxidation state, especially in basic environments, unlike its +4 state, which is more reactive.

Understanding these oxidation states is crucial because they directly influence how these elements bond and react in different environments.

Covalent Bonding

Covalent bonding involves the sharing of electron pairs between atoms. Group 14 elements extensively employ covalent bonding due to their four valence electrons, which allow them to form multiple bonds.

Carbon is a classic example. It forms exceptionally strong covalent bonds, allowing for complex molecules like chains, rings, and branches. This is the backbone of organic chemistry.

• Carbon easily forms stable double and triple bonds with itself and other elements due to its small size and high electronegativity. This results in a diverse range of carbon-based molecules.
• Silicon also forms covalent bonds, though it prefers single bonds, as seen in compounds like SiO₂.
• As we move to tin and lead, the covalent nature decreases, and metallic characteristics dominate, making their covalent compounds less stable.

Covalent bonding is essential as it defines the vast array of molecular structures we find in organic and inorganic chemistry.

Polymeric Structures

Polymeric structures are large molecules made up of repeating units. In Group 14, silicon is notorious for forming such structures, particularly with oxygen.

Silicon readily bonds with oxygen to create silica (SiO₂) and other polysilicates, where each silicon atom is bonded to four oxygen atoms in a tetrahedral arrangement.

• These polymeric structures form networks leading to materials like quartz and various types of glasses, which are highly durable and resistant to various environmental conditions.
• The formation of these networks occurs because silicon can share its electrons effectively with oxygen. These covalent bonds result in a stable, lattice-like structure.
• Other elements in the group, such as carbon, also form polymeric structures, although they are typically different in nature, like in graphite or polyvinyl chloride.

Polymeric structures are vital in both nature and technology, offering materials with unique properties.

Metallic Character

Metallic character refers to the tendency of an element to lose electrons and form positive ions. In Group 14, this property increases as you move down the group from carbon to lead.

Metallic character is associated with properties like conductivity, malleability, and a shiny appearance.

• Carbon is non-metallic, displaying properties distinct from metals, like poor conductivity in diamond form but conductive in graphite.
• Silicon, though more metallic than carbon, is classified as a metalloid. It has properties of both metals and nonmetals, making it essential in the semiconductor industry.
• Tin and lead are metals. Lead displays a higher metallic character than tin. Tin is soft and malleable, commonly used in alloys, while lead is denser and highly resistant to corrosion.

The metallic character influences how these elements interact and bond with others, particularly affecting their oxidation states and stability.