C2.3 - p1 Flashcards
what is an allotrope? (2)
- a form of an element in the same state (1)
- but with different atomic arrangements (1)
(ie. diamond, graphite)
state uses of graphene (1 layer thick, very strong and conducts electricity)
- solar panels
- batteries
- increases a material’s strength without adding much weight (composite materials)
what are fullerenes?
structures that have hollow shapes
describe the shape of fullerenes
- shaped as tubes/balls
what can spherical fullerenes be used for? (3)
- catalysts
- lubricants
- vectors for drugs into body (can pass through cell membranes)
what happens when chemical bonds form? (in terms of energy)
stored chemical energy is transferred to the surroundings
what are the bonds in simple molecules?
covalent forces between atoms, intermolecular forces between molecules
give examples of ionic compounds
sodium chloride
give examples of giant covalent structures
silica, diamond
give examples of simple molecules
oxygen, water,
what forces break when simple molecules boil/melt
the weak forces between the molecules, not the strong covalent bonds between each atom
(H20-H20) becomes H20 H20
what is the word used to describe when substances go directly from a solid to a gas?
sublimation
what is the word used to describe when substances go directly from a gas to a solid?
deposition
what determines whether a substance is brittle or malleable? (particles) (2)
how easily the particles in the substance can change (1) their positions in the lattice structure (1)
Evaluate why metals are malleable. (3)
attracting force between electrons and metal ions remain strong (1)
so bonds do not break (1)
instead layers of ions only slide over each other (1)
are giant covalent structure brittle?
yes
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Explain why ionic compounds are brittle. (3)
- in a giant ionic lattice, ions are arranged alternating with charges (1)
- when a force is applied, ions slide over each other (1)
- so new arrangement has like charges together, and so they repel (1) (pushing either side apart, and therefore breaking)
what allows a substance to conduct electricity?
whether or not it has delocalised electrons that can move
why do metals conduct electricity? (1)
it has delocalised electrons that are free to move (1) (through the lattice to carry the charge)
when do ionic compounds conduct electricity, and why?
- when molten/in the liquid state/ dissolved in water (1)
- ions are then free to move (1)
what are the size of nanoparticles?
between 1 and 100nm long
what are the size of coarse particles?
2,500 and 10,000nm long
disadvantages of using nanoparticles? (3)
- so small can be breathed in/absorbed
- may take a long time to break down
- difficult to predict (not much information known)
what are properties of nanoparticles because of a large surface area to volume ratio?
- efficient (less quantity used to make product)
what can nanoparticles be used for? (3)
- catalysts (larger surface area)
- medicine/drugs (deliver to a specific area of body)
- self-cleaning windows
- cosmetics (so small they are transparent)
why are nanoparticles good for cosmetics?
- so small that light passes through
(transparent)
why are nanoparticles good for cosmetics? (1)
They can be absorbed much deeper into the skin
