chp 1 Flashcards
material
substances that make other objects. often mixtures of many substances. can be pure (elements and compounds)
pure substances
Pure substances are defined as substances that are made of only one type of atom or molecule.
pure substance vs homogeneous mixture
homogeneous mixture: components can be separated
pure substances: can’t be separated
elements
substances made of one type of atom
compounds
pure substance made up of more than one type of atoms
pure substances
properties cannot be altered. properties are distinct and measurable for any given arrangement of atoms or molecules
mixtures
properties can be changed depending on how much of each component is added mixture.this useful as properties can be controlled.
individual components keep their properties
alloy
mixture of metal with other metals or small amount of non metals
e.g. iron is soft an sprone to corrosion. but adding some carbon creates steel which is stronger and corrosion resistant
polymer
material with a molecular structure that is composed of many repeating smaller units bonded together.
compared to metals, they are less dense, electrical insulator, corrosion resistant
natural: wool, silk, paper
synthetic: polystyrene
ceramic
inorganic, non metallic solid. composed of metals, nonmetals, metalloids held together by ionic and covalent bonds.
natural: kaolinite (makes porcelain)
synthetic: silicon carbide (used as an abrasive)
properties: hard, high compressive strength, able to withstand high temperatures. most are good insulators, but some have semi/super conducting properties
composite material
combination of two or more distinct materials with significantly different chemical and physical properties.
creates a range of properties that would be unobtainable with using one of the individual components.
e.g. reinforce concrete = concrete matrix +embedded steel bars
low tensile strength of concrete counteracted with steel
maintains high compressive strength of concrete
heterogeneous mixtures
non uniform mixtures that contain physically separate materials
not pure or uniform
mixtures can have different proportions of the same components .
eg. granite has 3 different minerals, each piece has a different amount but it is still granite
homogeneous material
materials that have uniform composition throughout
breaking it smaller = would be identical
homogeneous solution
consists of solute and solvent, solute is distributed throughout the solvent as very small particles, so it appears uniform
nanoscale
structure between 1 and 100 nm
nanometer = 10 ^-9
nanomaterial
substances (natural and synthetic) that are composed of single units that exist in ten nanoscale
very large surface area compared to the volume they occupy
adsorption
where molecules stick to surface of of a solid or liquid
can be used to remove unwanted chemicals and gases
large surface area means that a small volume of nanoparticles can adsorption a large number of molecules
transportation
can transport molecules that are adsorbed
small size and large surface area mean that they can transport chemicals through air, skin and even cells
used in chemotherapy treatments for cancer as it can transport drugs to specific cells
catalysts
can speed up rate of reaction without being altered or destroyed in the process. provide surface for reaction to occur
reactant molecules absorb onto the surface of the nanoparticles which allows reactant molecules to combine to form the product
large sa means many reactions can occur at once. ->increases rate of reaction
gold as nanoparticles
properties can change as nanoparticles
gold changes its colour
melt at lower temperatures and appear red in solution
zinc oxide in sunscreen
good absorbers of uv radiation and appear transparent because the particle size is much smaller than the wavelength of visible light, so light can go through it with very little being affected
other metal oxides tend to be milky white
having nanoparticles means that it’s distributed evenly so uv radiation is absorbed/scattered by zinc oxide. if they were bigger it means that it wouldn’t be evenly distributed and up rays could pass through
nanoparticles in medicine
colloidal gold: labeling antigens, optimises distribution of drugs to cells in difficult areas (brain, retina, tumours), targets tumors and provides detection
silver: antibacterial and antifungal properties, due realease of silver ion from surface of metal
sa enhances antibacterial effectiveness
safety nanoparticles
can travel through air, bloodstream, skin, cells
can interact with inside body (biomolecules) to cause unwanted reactions
composite nanomaterial
small size and unique properties are useful for them to be composite nanoparticles
stain resistant cotton: cotton fibres covered with water resistant nanoparticles
tyres: added carbon improved resistance and abrasion. increase electrical conductivity, prevents build up of static electricity
fullerenes
3d structures formed by networks or carbon atoms
nanotube: cylindrical tube, reinforcement in composite nanomaterial
graphene: flat 2d layer of carbon atoms arranged in hexagons
buckyball: soccer ball shaped 3d structure
top down
size of material is progressively reduced , by grinding until size is achieved.
+: large quantities produced, cheap, uniform
-: limited to simple structures
sieving
based on particle size
separates mixtures of different particles, smaller particles pass through holes, large ones are trapped
filtration
particles not dissolved in solvent
separates suspended solid from a liquid using a filter funnel and paper.
evaporisation
particles dissolved in liquid
boiling/evaporating solvent away from solute
distillation
differences in boiling point
separates two liquids with different boiling points or a soluble solid and the solvent
distillation flask, condenser, receiving flask
fractional distillation
vapour passes through a column packed with glass beads. less volatile component component condenses on the glass beads and drips back to distillation flask
can be used to separate miscible liquids
separating funnel
difference in density
immiscible liquids separate into layers due to density
tap is opened to let the more dense component out of the mixture
