Basics Flashcards
solids
- fixed shape/ volume
- can’t be compressed
- least KE
- regular arrangement
- vibrates in place
- strong intermolecular forces
liquids
- no fixed shape
- takes shape of bottom of container
- flows
- can’t be compressed
- no regular arrangement
- moves randomly
gases
- no fixed shape
- takes shape of whole container
- can be compressed
- no fixed volume
- weakest intermolecular forces
- no regular arrangement
- moves randomly quickly
solid to liquid
melting
liquid to gas
boiling/ evaporating
gas to liquid
condensation
liquid to solid
freezing
kinetic particle theory
- more kinetic energy= weakest forces
- higher temp. = more kinetic energy
pressure in gases decreases
volume increases
concentration
measure of a number of particles in a given volume
diffusion
net movement of particles from a region of high conc. to a region of low conc. down the conc. gradient
concentration gradient
difference in conc. of a fluid between 2 areas
greater molecular mass
particles move slower
effect of temperature on rate of diffusion
- higher temp. = more kinetic energy = move faster = increases rate of diffusion
element
substances made up of only one type of atom
compound
elements chemically bonded together (not easily separated)
mixture
substances found together, not chemically bonded (easily separated)
electrical conductivity in metals
- good electrical conductors
(they have delocalised electrons and are free to carry the charge)
thermal conductivity in metals
- good thermal conductors
malleability in metals
- very malleable
(easy to shape and bend)
ductility in metals
- very ductile
(easily stretched into wires)
melting/ boiling point of metals
- high melting/ boiling points
solvent
liquid in which a solute dissolves in
solute
substance that is dissolved in a solvent
solution
mixture of (1 or more) solutes dissolved in a solvent
saturated solution
solution with maximum conc. of a solute dissolved
filtrate
liquid/ solution that passed through a filter
residue
substance that remains after evap./ distillation/ filtration
Rf formula
distance travelled by solvent
mass number
larger number
proton number
smaller number
number of outershell electrons
group number
number of shells
period number
isotopes
atoms with the same proton number but different neutron number
group 7 (halogens)
- diatomic
- non-metals
- density increases going down
- melting point increases going down
- reactivity decreases going down
-iodine= grey-black solid - bromine= red-brown liquid
- chlorine= yellow-green gas
transition elements
- high density
- high melting point
- unreactive
- catalysts
- forms coloured compounds
- ions with variable oxidation numbers
group 8 (noble gases)
- colourless gases
- monoatomic
- very unreactive (inert)
collision theory
- particles must collide with correct orientation and sufficient energy (activation energy)
activation energy
minimum energy needed to create a reaction
effect of catalysts in activation energy
lowers it
cations
positive ions
anions
negative ions
ionic bond
strong electrostatic attraction between oppositely charged ions
properties of ionic compounds
- high melting/ boiling point
- good conductor when aqueous/ molten
- poor conductor when solid
- giant ionic lattice
- regular arrangement of alternating positive and negative ions
properties of covalent bonds
- low melting/ boiling point
-poor electrical conductor
covalent bonds
pair of electrons is shared between 2 atoms leading to a noble gas electronic configuration
diamond
- giant covalent
- carbon atoms only
- each carbon bonded to 4 others
- no delocalised electrons
- can’t conduct
- very hard, used for cutting tools
- high melting point
- doesn’t dissolve in water
graphite
- only carbon
- each carbon boded to 3 other
- organised in hexagons, making layers
- conducts electricity
- layers can slide over eachother (soft and slippery) (weak forces between layers)
- used as lubricant and electrode
silicon (IV) dioxide (SiO2)
- silicon bonded with 4 oxygens, oxygen bonded with 2 silicons
- high melting point
- doesn’t conduct
- doesn’t dissolve
- hard
metals and dilute acid
make salt and hydrogen
metals and water
make metal hydroxide and hydrogen
metals and oxygen
makes metal oxides
aluminium properties
- very low density
- strong
- good conductor
- corrosion resistant
used to make:
- aircrafts (low den.)
- overhead electrical cables (low den.)(good cond.)
- food containers (corrosion resistant)
copper use
- electrical wiring (ductile/ elec. cond.)
reactivity series order
potassium
sodium
calcium
magnesium
aluminium
carbon
zinc
iron
hydrogen
copper
silver
gold
potassium and water
- violent
- potassium floats , melts, catches fire
- burns with lilac flame
- hydrogen gas released
sodium and water
- floats, moves rapidly
- heat melts it
- hydrogen gas released
calcium and water
- water becomes milky white
- hydrogen gas released
aluminium’s unreactivity
- surface atoms react with oxygen in the air to form a protective aluminium oxide layer
- barrier to prevent inner metal from corroding
displacement reactions
- more reactive metal elements displace less reactive metal ions
- less reactive= reduced= gains electrons
- more reactive= oxidised= loses electrons
metallic bonding
electrostatic attraction between the positive metal ions in a giant metallic lattice and a sea of delocalised electrons
alloys
mixture of a metal with other elements
brass
mixture of copper and zinc
stainless steel
mixture of iron and chromium, nickel and carbon
used for cutlery (hard + resistant to rusting)
redox reactions
involving oxidation and reduction reactions and loss and gain of electrons and loss and gain of oxygen
oxidation
- gain of oxygen
- loss of electrons
- increase in oxidation number
reduction
- loss of oxygen
- gain of electrons
- decrease in oxidation number
oxidising agent
oxidises another substance and reduces itself
reducing agent
reduces another substance and oxidises itself
rusting
oxidation of iron
- conditions: air and moisture
iron + water + oxygen –> hydrated iron (iii) oxide
barrier methods
painting, coating with plastic, greasing, galvanising, sacrificial protection, greasing
sacrificial protection
- placing iron/ steel in contact with a more reactive metal (ie zinc)
galvanising
- coating iron/ steel with zinc
- barrier formed and if it is scratched, it is more reactive, so it corrodes instead of iron