Problem 102 - Chemistry: The Central Science in SI Units, Global Edition

Question

What evidence supports the notion that buckyballs are actual molecules and not extended materials? (a) Buckyballs are made of carbon. (b) Buckyballs have a well-defined atomic structure and molecular weight. (c) Buckyballs have a well-defined melting point. (d) Buckyballs are semiconductors. (e) More than one of the previous choices.

Step-by-Step Solution

Answer

(b) Buckyballs have a well-defined atomic structure and molecular weight.

Step 1: (a) Buckyballs are made of carbon.

Buckyballs being made of carbon does not indicate that they are molecules or extended materials. This statement simply describes the type of element that constitutes the buckyballs.

Step 2: (b) Buckyballs have a well-defined atomic structure and molecular weight.

A well-defined atomic structure and molecular weight are characteristics of molecules as they portray specific arrangements of atoms in a distinct, non-repeating unit with a well-defined mass. This statement supports the notion that buckyballs are molecules.

Step 3: (c) Buckyballs have a well-defined melting point.

Both molecules and extended materials can have well-defined melting points, as melting point is a property of a material regardless of its specific structure. Therefore, this statement does not provide support for the notion that buckyballs are molecules.

Step 4: (d) Buckyballs are semiconductors.

Semiconductors can be in the form of molecules or extended materials. Therefore, this statement does not provide support for the notion that buckyballs are molecules. Based on our evaluation, the correct answer is:

Step 5: (e) More than one of the previous choices.

In this case, the only statement that supports the notion that buckyballs are actual molecules and not extended materials is (b) Buckyballs have a well-defined atomic structure and molecular weight. Therefore, the answer should be (b), but since there is no multiple option, we conclude that the question might have a minor issue and the intended correct answer should be (e).

Key Concepts

Molecular Structure

Understanding molecular structure is key to grasping why buckyballs are classified as molecules. Buckyballs, also known as fullerenes, exhibit a well-defined atomic arrangement. Imagine a soccer ball: their shape resembles one with each carbon atom forming a vertex of a hexagon or pentagon. This creates a symmetrical and enclosed spherical shape.
This distinct shape means every individual buckyball has its own intrinsic properties, unique from merely a collective of atoms. Its molecular weight is a testament to this specificity. Unlike extended materials, where atoms are repetitively bonded in extended networks, buckyballs have a consistent number of atoms (typically 60 for the commonly studied C60 variety) and, therefore, a precise mass. This specified arrangement underpins the concept of molecular structure in chemistry.
Recognizing these characteristics helps us understand why buckyballs aren't just random assemblies of carbon: they're molecular structures with rigid architectural precision.

Carbon Compounds

Carbon compounds, such as buckyballs, are fascinating because carbon is uniquely versatile in forming various structures. Buckyballs are one of multiple forms of carbon, joining others like graphite and diamonds. Each form has its own properties, but the key here is how carbon forms these unique structures.
Carbon's ability to create four covalent bonds makes it exceptionally adaptable. In buckyballs, each carbon atom bonds with three others, forming a stable and robust cage-like framework. This is different from other allotropes where the bonding differs. While diamonds form a 3D lattice and graphite forms layers, buckyballs consist of a finite, closed molecular structure made entirely from carbon atoms.
This diversity in bonding showcases the remarkable nature of carbon compounds, where the same element can lead to such different molecular forms and properties.

Semiconductors

Buckyballs' role as semiconductors adds another layer to their versatile utility. Semiconductor materials have an electrical conductivity between conductors, like metals, and insulators, like glass. This property is crucial for the operation of electronic devices.
The semiconductor property in buckyballs arises from their electronic structure which allows for controlled flow of electricity. Because of the carbon network's configuration, these molecules can accept and donate electrons which are pivotal for semiconductor action.
This ability makes buckyballs exciting candidates for use in creating new, flexible, and efficient electronic components, potentially impacting anything from solar cells to lightweight transistors. The fact that buckyballs can participate in semiconductor applications signifies their importance not just in theoretical chemistry, but also in practical technology fields.