Studied by 3 people
plum- pudding model
ball of positive charge with negatively charged electrons distributed evenly throughout it
belief of atom before discovery of electron
tom believed to be indivisible
experiment which caused plum pudding model to be discarded
rutherford’s alpha- scattering experiment
current model of the atom
bohr nuclear model
three subatomic constituents of atom
proton, neutron, electron
arrangement of protons, neutrons and electrons in atom
protons and neutrons are found in nucleus and electrons found in discrete energy levels around the nucleus
charge of nucleus of atom
positive as it contains protons and neutrons. protons have a positive charge and neutrons have no charge
most of mass of atom
in nucleus
what proportion of total radius of atom is radius of nucleus
1/10,000
radius of atom
1×10^-10 metres
density
mass per unit volume of material
density equation
density = mass/ volume
particle arrangement of solid
tightly packed in regular arrangement. particles can only vibrate on spot
particle arrangement of liquid
close together but irregular arrangement. can flow past each other
particle arrangement of gas
separated with no regular arrangement. can move freely
states of matter in order of least to most density
gas, liquid, solid
what is conserved when substance undergoes change of state
mass
5 ways substance can change state
melt, freeze, evaporate, condense, sublimate
sublimation
when substance transitions from solid straight to gas without transitioning into liquid in between
difference between chemical change and change of state
in change of state, material can return to having previous properties if change reversed
what can heating substance do
raise temp, change state
definition of specific heat capacity
amount of energy needed to increase 1kg of substance by 1 degree celsius
what can be said about material if specific heat capacity is higher
for constant mass, substance will need more energy to acheive temp change
definition of specific latent heat
amount of energy needed to change state of 1kg of substance with no temp change
equation for energy required to change state
E = mL
what is internal energ of substance
energy stored by particles, sum of total kinetic + potential energies that make up system
describe motion of molecules in gas
in constant random motion
unit for pressure
Pa (pascal)
how can pressure of gas be increased while at constant tmep
volume decreased
how can pressure of gas be decreased whilst at constant temp
increase volume
effect of increasing temp on pressure of gas when held at constant volume
pressure of gas will increase as temp increases
why does pressure increase as temp increases at constant volume
kinetic energy of molecules increased therefore collisions between molecules more frequent. greater force therefore greater pressure
if gas a at low pressure and gas b at high pressure what can be said about rate of collision
more collisions per second in gas b than a. rate of collisions higher in b
describe force that pressure of gas exerts on walls of container
net force acts on right angles to container’s surface. magnitude of force increases as pressure increases
explain how increase in volume results in decrease of pressure
molecules become more spread out so collisions become less frequent reducing rate of collisions causing force on container to decrease. this decreases pressure
what can be said about product of pressure and volume for fixed mass of gas at constant temp
it is constant , pV = constant
what increases when work done on gas
internal energy of gas, can also lead to increase in temp
why does temp of air inside bicycle wheel increase when pumped
work is done on gas when compressed. doing work increases internal energy so increases average kinetic energy of molecules. temp increases with increase of average kinetic energy
why does atmospheric pressure decrease as height above earth’s surface increases
number of gas molecules in given volume of air decreases causing frequency of collisions to decrease, decreasing pressure
what does object in fluid experience as result of pressure
forces at right angles to all its surfaces
what happens to pressure in fluid with depth
pressure increases as the deeper you go, greater the weight of water above you therefore higher force resulting in higher pressure
equation used to calculate pressure at given depth of liquid
pressure = height × density × gravitational field strength
upthrust
upwards force an object experiences in fluid as result of greater pressure below object than above
under what circumstances will object float
when upthrust = weight
under what circumstances will object float
when upthrust less than weight
when object submerged in liquid what is upthrust acting on object equal to
weight of volume of liquid displaced as submerged
what can be said about density of object that sinks in water
density greater than density of water
boyle’s law
volume is inversely proportional to pressure
equation of boyle’s law
pv = constant
Note
Flashcard