Bulk and surface properties of matter

• Nanoparticles are 1-100 nanometers across
• Nanoparticles contain a few hundred atoms
• Nanoparticles are smaller than fine particles (PM2.5), which have diameters between 100 and 2500 nm
• Coarse particles (PM10) have diameters between 1 x 10^-5 m and 2.5 x 10^-6 m and are often referred to as dust
• As the side of a cube decreases by a factor of 10, the surface area to volume ratio increases by a factor of 10
• Nanoparticles involve fullerenes
• A nanoparticle has different properties to the 'bulk' chemical it's made from due to their high surface area to volume ratio
• Smaller quantities of nanoparticles may be needed to be effective compared to materials with normal particle sizes
• Uses of nanoparticles:

  • They make good catalysts due to their high surface area to volume ratio
  • They can be used to produce highly selective sensors
  • Nanotubes could make stronger, lighter building materials
  • Used in new cosmetics like sun tan cream and deodorant without leaving white marks
  • Lubricant coatings reduce friction and can be used for artificial joints and gears
  • Nanotubes conduct electricity and can be used in small electrical circuits for computers
• Possible disadvantages of nanoparticles:

  • Concerns that nanoparticles may be toxic to people
  • They may be able to enter the brain from the bloodstream and cause harm