View
224
Download
0
Category
Preview:
Citation preview
Metallic and Ionic Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
2
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
3
Think
Coordination Numbers!
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
4
Attracted to lots of nearest neighbors
High Coordination Numbers
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
5
Low Coordination Numbers
Nanoparticles
Attracted to few nearest neighbors
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
6
E (surface
atoms)
- E (interior
atoms)
Surface Energy!
= E (surface)
Nanoparticles
Higher energy!Surface atoms have
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
7
Smaller Sample Larger Sample
Metallic CrystalNanoparticle
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
8
…is where the interactions that result in changes in physical and chemical properties occur.
…is where chemical reactions take place.
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
9
Factors that affect the RATE of chemical reactions
1. Size of reaction particles and increasing surface area 2. Concentrations of reactants3. Temperature
4. Presence of a catalyst
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
10
As the size of nanoscale particles decreases,
the surface area to volume ratio increases.
Therefore, the surface energy increases!
What factors account for the increase in reaction rates of chemical processes at the nanoscale level?
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
11
Adsorption takes place at the surface.
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
12
7 grams of nanoparticles (four nm) have a surface area equivalent to a football
field
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
13
Catalytic reactions takes place at the surface.
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
14
Scanning Electron Microscop (SEM) showing the vertical growth of nanowires on a gold catalytic surface for electronic
devices (Stanford Nanofabrication Facility)
Gold Catalytic Surface
Nanowires
Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
15
Increase the rates of some chemical reactions
Decreases in the size of particles
Increases in surface area
Metallic and Ionic Nanoparticles
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
16
Iron nanoparticles in YOUR backyard?
Nanoparticles
http://www.phschool.com/science/science_news/articles/special_treatment.html
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
17
1. What chemical properties were most effected by surface energy?
2. How were the chemical properties affected by surface energy?
3. What physical properties might be affected by surface energy?
Making Connections
Extendable Structures: Reactivity, Catalysis, Adsorption© McREL 2009
18
Lesson 1.2 What Makes Nanoscience so Different?
What makes Nanoscience so different?Compare Newtonian and Quantum Chemistry Regimes as they relate to nanoscale science
Lesson 1.3 What Makes Nanoscience so Important?
Interdisciplinary science The development of new technologies and instrumentation applications whose risk and benefits have yet to be determined
Lesson 3.1Carbon Chemistry
Lesson 1.1 What is Nanoscience?
What is Nanoscience? Examine and Compare size: macro, micro, sub-micro (nano)SI prefixes
Lesson 2.2 Extendable Solids: Reactivity, Catalysis, Adsorption
The difference between the energy at the surface atoms and energy of the interior atoms results in increased surface energy at the nanoscale
Higher surface energy allowing for increased reactivity, adsorption, and catalysis at the nanoscale
Lesson 2.3Extendable Structures: Melting Point, Color Conductivity
Lesson 3.2Fullerenes and Nanotubes
Lesson 2.1 Extendable Solids
As the size of the sample decreases the ratio of surface particles to interior particles increases in ionic and metallic solids
Poster Assessment
Students will further investigate the essential question that they have considered throughout the module: How and why do the chemical and physical properties of nanosamples differ from those of macrosamples?
Module Flow Chart
Recommended