Nanotechnology Flashcards
What is a nanometre?
A nanometre (nm) is a unit of length in the metric system equal to one-billionth of a metre (10^-9 meters).
What is technology?
Technology is the making, usage, and knowledge of tools, machines, and techniques used to solve problems or perform specific functions.
How small is a nanometer?
Here are some comparisons to help visualize the size:
1,000 nanoparticles could fit across the width of a human hair.
A red blood cell is about 7,000 nm in diameter.
A DNA molecule is roughly 2 nm wide.
What is the size range of nanomaterials?
Nanomaterials are typically between 1 and 100 nanometers (nm) in size.
Who coined the term “nanotechnology”?
Norio Taniguchi (1974)
Who presented ideas for creating nanoscale machines?
Richard Feynman (1959)
What technological advancement significantly boosted nanotechnology development in the 1980s?
Advances in electron microscopy
Why do the properties of materials change at the nanoscale?
There are two main reasons:
Increased Surface Area: Nanoparticles have a much larger surface area to volume ratio compared to their bulk counterparts. This can make them more chemically reactive and affect their strength, electrical properties, and other characteristics.
Quantum Effects: At the nanoscale, the behavior of matter can be influenced by quantum mechanics, which governs the behavior of atoms and subatomic particles. These effects can significantly alter material properties compared to the bulk scale.
How are nanoscale materials categorized?
Nanoscale materials can be categorized based on the number of dimensions in which their size is confined:
Zero-dimensional (0D): All three dimensions (length, width, height) are confined to a single point. (Example: Quantum dots)
One-dimensional (1D): Only one dimension is unrestricted, like length in a very thin wire or diameter in a nanotube.
Two-dimensional (2D): Two dimensions are unrestricted, like length and width in a thin film or sheet. (Example: Nanowires, nanotubes)
Three-dimensional (3D): All three dimensions have some degree of confinement, but not necessarily limited to a single point. (Example: Nanoparticles)
What are the two main approaches for synthesizing nanomaterials?
Top-Down Approach: This approach involves breaking down bulk materials into smaller nanoparticles.
Bottom-Up Approach: This approach builds up nanomaterials from individual atoms or molecules.
What is an example of a top-down approach?
High-Energy Ball Milling: This technique uses a high-energy grinding process to break down bulk material into nanoparticles.
What is an example of a bottom-up approach?
Sol-Gel Process: This wet-chemical method involves the formation of a liquid precursor (sol) that transforms into a gel and then into a final nanomaterial.
How do quantum effects influence material properties?
Quantum effects can alter various properties of materials at the nanoscale. For example, they can affect the electronic band structure, leading to changes in optical properties, conductivity, and magnetism. Additionally, quantum confinement can affect the way light interacts with the material.
Who discovered fullerenes and when?
A team of scientists at Rice University, Houston, Texas, discovered fullerenes experimentally in September 1985.
Who were the scientists awarded the Nobel Prize for the discovery of fullerenes?
Robert Curl, Harold Kroto, and Richard Smalley received the Nobel Prize in Chemistry in 1996 for their discovery of fullerenes.
What is a fullerene?
A fullerene is any molecule composed entirely of carbon atoms arranged in a closed or partially closed cage-like structure. These structures can be ellipsoidal, tubular, or hollow spheres, resembling shapes like buckyballs or nanotubes.
What is the name of the first discovered fullerene?
Buckyball (Buckminsterfullerene)
What is the molecular formula of a buckyball?
C60 (60 carbon atoms)
What is the defining characteristic of a buckyball?
A buckyball is a true hollow sphere, entirely composed of carbon atoms linked together.
Why is the buckyball named Buckminsterfullerene?
It is named after Richard Buckminster Fuller, an architect known for his geodesic domes, which share a similar spherical structure with multiple faces.
How did Kroto, Smalley, and Curl discover fullerenes?
They used a laser vaporization technique on graphite to produce carbon soot, from which they were able to isolate microscopic quantities of fullerenes.
What is the Krätschmer-Huffman method?
This method, developed by Krätschmer and colleagues, allows for macroscopic production of fullerenes.
How does the Krätschmer-Huffman method work?
Graphite electrodes are gently held in contact.
An electric current is passed through the electrodes in a helium atmosphere.
The heat from the current vaporizes the graphite, forming carbon soot.
The soot is dissolved in a nonpolar solvent.
The solvent is evaporated, leaving behind a residue containing fullerenes (including C60 and C70) which can then be separated.
What are the three main types of fullerenes based on how atoms are arranged?
Exohedral Fullerenes: In these fullerenes, atoms, molecules, or even clusters of atoms are attached to the outer surface of the fullerene cage.
Endohedral Fullerenes: In contrast to exohedral fullerenes, endohedral fullerenes encapsulate molecules or atoms inside the hollow cavity of the fullerene cage.
Nanopeapods: These are a specific type of endohedral fullerene where fullerenes are encapsulated within carbon nanotubes.
What is an example of an application of endohedral fullerenes?
Endohedral fullerenes are being explored for various potential applications, including drug delivery due to their unique ability to encapsulate and protect guest molecules.
What is the significance of nanopeapods?
Nanopeapods combine the properties of fullerenes and carbon nanotubes, potentially leading to new materials with unique electronic, magnetic, and mechanical properties. They are being investigated for applications in areas like nanoelectronics and hydrogen storage.
Does Buckminsterfullerene exhibit “super aromaticity”?
No, Buckminsterfullerene does not exhibit “super aromaticity.” This means the electrons in its hexagonal rings are not delocalized across the entire molecule.
What is the hybridization of carbon atoms in Buckminsterfullerene?
The carbon atoms in Buckminsterfullerene are a mixture of sp2 and sp3 hybridization. The sp2 hybridization contributes to the molecule’s stability, but also creates angle strain due to the non-ideal bond angles.
Are fullerenes completely unreactive?
Are fullerenes completely unreactive?
What is the solubility of Buckminsterfullerene?
Fullerenes are sparingly soluble in many solvents. However, they show good solubility in some specific solvents, including:
Aromatic solvents like toluene
Other solvents like carbon disulfide
What makes fullerenes unique in terms of solubility?
Fullerenes are the only known allotrope of carbon (like diamond or graphite) that can be dissolved in common solvents at room temperature.
What discovery about C60 was made in 1991?
Potassium-doped C60 (C60 doped with potassium atoms) was found to exhibit superconductivity at 18 Kelvin (K), which was the highest transition temperature for a molecular superconductor at that time.
