2. Factors Influencing Properties MacroscaleNanoscale Surface area to volume ratioSmallVery large GravityVery importantLess important Electromagnetic forcesLess importantVery important Random Motion Insignificant compared with size Large influence

3. Surface Area

4. Gravity and Electromagnetic Forces Gravitational force –Depends on mass –Larger influence on heavier particles –Insignificant for very small particles Electromagnetic forces –Do not depend on mass Force due to gravity

5. Changing Properties Types of properties that often change –Optical (e.g. colour, transparency) –Electrical (e.g. conductivity) –Physical (e.g. hardness, boiling point) –Chemical (e.g. reactivity, reaction rates)

6. Electrical Conductivity Bulk MetalNanomaterials Negatively charged particles particles (electrons) move around a fixed arrangement of positively charged particles. Electrons can move so they can conduct electricity Less electrons to “share” Electrons tend to stick close to one positive charge and not move around. Not as good at conducting electricity.

7. Optical Properties Particles are so small that electrons are not free to move about. Because this movement is restricted, the particles react differently with light. Some particles are so small that visible light does not interact with them at all.

8. Melting Related to percentage of atoms on the surface (i.e. surface area to volume ratio)

9. Reactivity