Question

Select the member of group 4 A that best fits each description: (a) forms chains to the greatest extent, (b) forms the most basic oxide, (c) is a metalloid that can form \(2+\) ions.

Short answer

(a) Carbon (C) forms chains to the greatest extent due to its small atomic size and strong covalent bonds. (b) Lead (Pb) forms the most basic oxide, PbO₂, as the oxides become more basic in character moving down the group. (c) Germanium (Ge) is a metalloid that can form 2+ ions due to the inert pair effect.

Step-by-step solution

(a) Element forming chains to the greatest extent

In Group 4A, Carbon (C) has the unique ability to form long chains, as well as rings and complex structures, due to its small atomic size and the strength of the carbon-carbon bond (covalent bond). This is the basis for organic chemistry and the formation of a wide variety of organic molecules. Therefore, the element that forms chains to the greatest extent is Carbon (C).

(b) Element forming the most basic oxide

Group 4A elements form oxides with the general formula MO₂. As we move down the group, the oxides become more basic in nature, as the metal character of the element increases. Carbon forms CO₂, which reacts with water to form the acidic H₂CO₃. Silicon forms SiO₂, which has acidic and neutral properties. Germanium forms GeO₂, which has acidic and basic properties. Tin forms SnO₂ which is amphoteric, and Lead forms PbO₂ which is also amphoteric but more basic in character. Therefore, the element forming the most basic oxide is Lead (Pb).

(c) Element that is a metalloid and can form 2+ ions

Metalloids are elements that have properties between those of metals and nonmetals. In Group 4A, Silicon (Si) and Germanium (Ge) are considered metalloids. Both have a +4 oxidation state but Germanium (Ge) can also form 2+ ions due to the inert pair effect which arises from the reluctance of the electrons in the completely filled s-orbitals to participate in bonding. Therefore, the metalloid capable of forming 2+ ions is Germanium (Ge).

Key concepts

Formation of Chemical Chains

The unique qualities of carbon allow it to create various types of chemical chains; this is essential for life as we understand it. Carbon's small atomic size gives it the ability to form strong covalent bonds with other carbon atoms, facilitating the construction of complex organic molecules. This versatility leads to long chains and intricate compounds, from simple hydrocarbons to massive molecules like DNA.

Understanding the formation of these chains helps us grasp the foundations of organic chemistry, where carbon's ability to catenate, or link with itself, governs the structure and function of a multitude of organic substances. It's interesting to note that among the group 4A elements, only carbon shows this tendency to an extensive degree, underlining its unique role in the chemistry of life.

Basicity of Metal Oxides

Metal oxides have vital chemical properties where their basicity or acidity holds significant implications for both industrial and environmental chemistry. Tin (Sn) and lead (Pb), being more metallic, form oxides that exhibit more basic characteristics, referring to their ability to neutralize acids.

As the metallic character increases down the group, these oxides react differently with water. While carbon's CO₂ forms an acidic solution, lead's PbO₂, being the most metallic, produces a more basic solution. This trend is beautifully exemplified in the transition from the acidic carbon dioxide to the significantly more basic lead dioxide, showcasing the underlying principle that basicity increases with metallic character within group 4A.

Metalloid Properties

Metalloids like silicon (Si) and germanium (Ge) exhibit a fascinating blend of metallic and nonmetallic properties, setting them apart within group 4A. Their ability to semi-conduct electricity is one of their most critical technological applications, bridging the gap between the conductive metals and the insulative non-metals.

Germanium can also form 2+ ions reflecting its metalloid characteristics. This arises from the 'inert pair effect'—a reluctance of s-orbital electrons to partake in bonding. Germanium's capability to adopt a +2 oxidation state while mostly preferring a +4 state reveals the delicate balance metalloids strike between metal and nonmetal behavior.

Oxidation States

Oxidation states are integral to understanding the versatility and reactivity of elements within group 4A. These states indicate the number of electrons an atom can gain, lose, or share during chemical reactions. Carbon primarily exhibits a +4 oxidation state but can also display other states in organic compounds. This variability is central to the rich diversity of organic chemistry.

As one descends the group, heavier elements like tin and lead show an inert pair effect. Lead's ability to stabilize +2 and +4 oxidation states is crucial for its various applications, from batteries to shielding materials. The oxidation states within group 4A elements provide a window into their chemical behavior, guiding us through the group's transition from nonmetallic to more metallic character.