11) Nanoparticle

Size: Nanoparticles are incredibly small particles, ranging from 1 nm (1 x 10^-9 m) to 100 nm (1 x 10^-7 m) in diameter.
Composition: They consist of only a few hundred atoms, while a typical atom has a diameter of about 0.1 nm (1 x 10^-10 m).
Types of Particles:
- Coarse Particles (PM10): Diameter between 2.5 x 10^-5 m and 10,000 m (1 x 10^-5 m); also known as dust.
- Fine Particles (PM2.5): Diameter between 100 nm (1 x 10^-7 m) and 2,500 m (2.5 x 10^-6 m).

This is the field of science that studies nanoparticles and their unique properties and uses.

Definition: The surface area to volume ratio affects how particles behave.
- Formula: Surface area to volume ratio = surface area ÷ volume
Effect of Size: As particles decrease in size, their surface area increases relative to their volume, resulting in a higher surface area to volume ratio.
Example Calculation:
- Cube with 100 nm sides:
  - Surface area: 6 × (100 nm × 100 nm) = 60,000 nm²
  - Volume: 100 nm × 100 nm × 100 nm = 1,000,000 nm³
  - Ratio: 60,000 nm² ÷ 1,000,000 nm³ = 0.06 nm^-1
- Cube with 10 nm sides:
  - Surface area: 6 × (10 nm × 10 nm) = 600 nm²
  - Volume: 10 nm × 10 nm × 10 nm = 1,000 nm³
  - Ratio: 600 nm² ÷ 1,000 nm³ = 0.6 nm^-1
Implications: Nanoparticles have a very high surface area to volume ratio, meaning their surface area is much larger compared to their volume, leading to different properties compared to bulk materials.

The unique properties of nanoparticles can make them more effective than bulk materials, such as needing less of a nanoparticle-based catalyst to achieve the same effect as larger particles.