Nanotechnology Flashcards
Allotype
one or more forms of a chemical element that can exist in the same physical state
Nanometre
one billionth of a metre
Nanoscale
structures that are between 1-100 nanometres across
Nanotechnology
branch of materials that investigates the design, properties and applications of materials produced on this scale
Nanomaterials
substances (natural and synthetic) that are composed of single units that exist in the nanoscale
Nanomaterials can differ from bulk materials
by surface area, size and quantum effects
Carbon - s,p,a,ad,d
Structure – carbon nanotubes
Properties – high electrical and thermal conductivity
Applications – electronics (transistors, interconnects)
Advantages – versality
Disadvantages – health risks (toxicity)
Metallic - s,p,a,ad,d
Structure - gold
Properties – high surface area
Advantages- tailored properties – control size, shape, surface chemistry
Applications – catalysis for chemical reactions
Disadvantages – stability issues
Carbon links to electronic devices
electrical conductivity makes them suitable for use in electronic devices due to their delocalized electrons
Metallic links to catalysis
large surface area enhances reactabilty and makes them ideal for catalysis for surface interactions due to their small size (large surface area relative to volume)
Comparison of carbon to silicon and metal
Silicon – has electrical properties but is rigid and has limitations to miniaturization due to its size
Metal (copper) - highly conduction but lack flexibility and is too bulky for smaller devices
Comparison of metallic to bulk metals and metal oxides
Bulk metals – have lower surface areas which limits catalytic activity
Metal oxides – can have catalytic activity influenced by surface structure and oxygen vacancies
Why are other materials used in favor of nanomaterials?
All of these materials are used in favor of nanomaterials due to them being cheaper, more environmentally and health friendly and offering more stability
Health risks involved in carbon
CNTs can cause lung damage / inflammation due to inhalation exposure as small particles allows them to penetrate respiratory system
Health risks involved in metallic
causes toxicity to aquatic animals and impacts our health through consumption of contaminated seafood due to their small size (bioaccumulation)
Health risk in nanomaterial
can lead to oxidative stress, tissue damage and physiological damage
Regulations to combat health risks for carbon
control measures like enclosed systems, ventilations and PPE
Regulations to combat health risks for metallic
waste management like special collection and treatment processes for safe disposal
John Dalton
Theory –
Matter is made up of invisible atoms
Atoms and elements have different mass and properties
Atoms combine in a simple whole number ratios to form compounds
Experiments –
gas pressure studies and analysis of compound composition
Thompson
Theory -
Created the plum pudding model = sphere of positive charge with electrons embedded in the sphere with an overall neutral charge because charges balanced
Experiment –
cathode ray tube = studied behavior of rays emitted when a high voltage was applied
Rutherford
Theory –
Atoms have a positively charged nucleus (center) surrounded by empty space
Electrons orbit in the empty space
Experiment –
Gold foil experiment = most positively charged particles passed through but some deflected
Alpha particle scattering
Bohr
Theory –
Electrons exist in energy levels
Further electrons orbit the less energy
Electrons cannot exist between levels
Size of electrons orbit increases with energy level
Experiment –
observed emission spectra of hydrogen atoms
Chadwick
Theory –
Neutron with similar mass to protons in the atomic nucleus – discovered existence of neutron
Experiment –
Used polonium source to emit alpha particles directed at beryllium target to produce unknown radiation then into wax (hydrogen) as protons ejected
