chp 1

Question 1

material

Answer 1

substances that make other objects. often mixtures of many substances. can be pure (elements and compounds)

Question 2

pure substances

Answer 2

Pure substances are defined as substances that are made of only one type of atom or molecule.

Question 3

pure substance vs homogeneous mixture

Answer 3

homogeneous mixture: components can be separated

pure substances: can’t be separated

Question 4

elements

Answer 4

substances made of one type of atom

Question 5

compounds

Answer 5

pure substance made up of more than one type of atoms

Question 6

pure substances

Answer 6

properties cannot be altered. properties are distinct and measurable for any given arrangement of atoms or molecules

Question 7

mixtures

Answer 7

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

Question 8

alloy

Answer 8

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

Question 9

polymer

Answer 9

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

Question 10

ceramic

Answer 10

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

Question 11

composite material

Answer 11

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

Question 12

heterogeneous mixtures

Answer 12

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

Question 13

homogeneous material

Answer 13

materials that have uniform composition throughout

breaking it smaller = would be identical

Question 14

homogeneous solution

Answer 14

consists of solute and solvent, solute is distributed throughout the solvent as very small particles, so it appears uniform

Question 15

nanoscale

Answer 15

structure between 1 and 100 nm

nanometer = 10 ^-9

Question 16

nanomaterial

Answer 16

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

Question 17

adsorption

Answer 17

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

Question 18

transportation

Answer 18

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

Question 19

catalysts

Answer 19

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

Question 20

gold as nanoparticles

Answer 20

properties can change as nanoparticles

gold changes its colour
melt at lower temperatures and appear red in solution

Question 21

zinc oxide in sunscreen

Answer 21

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

Question 22

nanoparticles in medicine

Answer 22

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

Question 23

safety nanoparticles

Answer 23

can travel through air, bloodstream, skin, cells

can interact with inside body (biomolecules) to cause unwanted reactions

Question 24

composite nanomaterial

Answer 24

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

Question 25

fullerenes

Answer 25

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

Question 26

top down

Answer 26

size of material is progressively reduced , by grinding until size is achieved.

+: large quantities produced, cheap, uniform

-: limited to simple structures

Question 27

sieving

Answer 27

based on particle size

separates mixtures of different particles, smaller particles pass through holes, large ones are trapped

Question 28

filtration

Answer 28

particles not dissolved in solvent

separates suspended solid from a liquid using a filter funnel and paper.

Question 29

evaporisation

Answer 29

particles dissolved in liquid

boiling/evaporating solvent away from solute

Question 30

distillation

Answer 30

differences in boiling point
separates two liquids with different boiling points or a soluble solid and the solvent

distillation flask, condenser, receiving flask

Question 31

fractional distillation

Answer 31

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

Question 32

separating funnel

Answer 32

difference in density
immiscible liquids separate into layers due to density

tap is opened to let the more dense component out of the mixture