P3 key questions
How much mass a substance contains compared to it's volume is… density
State the equation which links density, mass and volume ρ=m/v
Name the change of state when a liquid becomes a solid freezing
Name the change of state when a solid becomes a liquid melting
Name the change of state when a liquid becomes a gas evaporation
Name the change of state when a gas becomes a liquid condensation
Name the change of state when a solid becomes a gas (without passing through liquid form) sublimation
Changes of state are caused by the amount of _________ a substance has energy
State changes are examples of ___________ change physical
Physical changes are ones which can be _____________ reversed
A change which creates new products and cannot be reversed is _________ change chemical
The energy stored inside a system by the particles which make it up is known as ____________ energy internal
What is internal energy? The total kinetic energy and potential energy of all the particles in a system
Energy stored within moving objects is __________ kinetic
Energy stored in particles because of their position is…? potential energy
Particles wich are further apart have _________ potential energy more
The energy needed to raise the temperature 1 kg of a material by 1ᵒC is the __________ specific heat capacity
The average kinetic energy of particles is known as the ___________ temperature
The amount of energy required to change the state of one kilogram of a substance with no change in temperature is the …? specific latent heat
Latent heat of fusion is for changing…? solid to liquid
Latent heat of vaporisation is for changing….? liquid to vapour (gas)
Increasing temperature ______________ pressure in a gas if volume is constant increases
The force exerted by gas on a surface as the particles collide with it is known as….? gas pressure
State the units of density kg/m3
State the units of volume m3
Sketch the heating curve for water teacher to draw on board…
Draw a particle diagram for a solid teacher to draw on board…
Draw a particle diagram for a liquid teacher to draw on board…
Draw a particle diagram for a gas teacher to draw on board…
Why doesn't temperature increase during melting? Energy is being used to weaken forces between particles
Why doesn't temperature increase during evaporation Energy is being used to weaken forces between particles
Why does temperature of a substance increase as it is heated? Particles gain more kinetic energy and temperature is a measure of kinetic energy
Particles are arranged regularly in a ….? solid
Particles are arranged randomly, but touching in a …? liquid
Particles move around randomly in a ….? gas
Define atom The smallest part of an element that can exist.
All substances are made up of…? atoms
The radius of an atom is …? 0.1 nm (1 x 1010 m)
The overall charge on an atom is… zero/neutral
Define element Contains only one type of atom
Substances found in the periodic table are…? elements
Approximately how many elements are there? 100
Define isotope An atom of the same element with different numbers of neutrons
Define radioactive decay An unstable nucleus changes to become more stabe and gives out radiation
We cannot predict when a given atom will decay, this means that radioactive deacy is ….? random
Define activity Rate at which decay occurs
What are the units of activity? Becquerels (Bq)
Define count rate Number of decays recorded each second by a Geiger-Muller tube
Defne half life The time taken for number of radioactive nuclei in a sample to halve OR time taken for count rate (or activity) from a sample to fall to half its initial value
Define contamination The unwanted presence of materials containing radioactive atoms
Define irradiation When an object is exposed to radiation
Does an irradiatied object become radioactive itself? no
The process of radiation removing electrons from atoms to form ions is called…? ionisation
If ionisation happens in DNA it can cause ___________ which may result in ____________ mutations, cancer
Define peer review Checking of scientific results by other scientific experts
Define mass number The total number of protons and neutrons in an atom
Define atomic number The number of protons in an atom (number of electrons is the same in a neutral atom)
Electrons in atoms are located in ___________ energy levels
Absorption of radiation by an atom may result in ____________ moving to a ________________ energy level electrons, higher
Emission of radiation from an atom may lead to _____________ moving to a ______________ energy level electrons, lower
Who came up with the Plumb Pudding model of the atom J J Thompson
Describe the Plumb Pudding model of the atom A ball of positive charge with negative electrons embedded in it
Was the Plumb Pudding model correct? no
What experiment did Rutherford do? Alpha particle scattering
What did Rutherford's experiment reveal? Atoms have a central area of positive charge with electrons surrounding it
Who discovered that electrons are located in energy levels? Niels Bohr
What did Jame Chadwick discover about the atom? That the nucleus contains neutrons as well as protons
What did John Dalton contribute to our understanding of atomic theory? Matter is made up of descrete, spherical particles, known as atoms
Name the three subatomic particles proton, neutron, electron
Which particles are located in the atoms nucleus protons, neutrons
What is the charge of each subatomic particle? proton +1, neutron 0, electron -1
What is the mass of each subatomic particle? proton 1, neutron 1, elecrton ≈ 0
Name the three types of radiation alpha, beta and gamma
What is an alpha particle? two protons and two neutrons
What is a beta particle? an electron
What is gamma radiation? electromagnetic wave (NOT a particle)
What is the range of alpha radiation in air? short - 5 cm in air
What is the range of gamma radiation in air? unlimited in air
What's the range of beta radiation in air? medium - about 1 m
What will absorb (stop) alpha radiation? paper/skin
What will absorb (stop) beta radiation? about 5 mm aluminium
What will absorb (stop) gamma radiation? several centimetres of lead
What is the ionising power of alpha radiation? very high
What is the ionising power of beta radiation? medium
What is the ionising power of gamma radiation? low
What is meant by the ionising power of radiation? how likely it is to ionise atoms which it comes into contact with
How does alpha decay alter the mass number of the parent nucleus? decreases by 4
How does alpha decay alter the atomic number of the parent nucleus? decreases by 2
How does beta decay alter the mass number of the parent nucleus? stays the same
How does beta decay alter the atomic number of the parent nucleus? increases by 1
How does gamma radiation alter the mass and atomic number of the parent nucleus unchanged (energy is released as the particles in the nucleus reorganise to a lower energy arrangement)