Paper 1 Flashcards
(55 cards)
why was the plum pudding theory disproved
in 1909 Rutherford and Marsden tired firing a beam of alpha particles at thing gold foil and they excepted particles to pass straight through the gold sheet or to be only slightly deflected but somewhere deflected lots and in the same way they came in which disproved the theory showing that most of the mass of an atom was a nucleus and it must be positive since in repelled the positive alpha particles and most of the atom is empty space
what is the overall size of an atom
1 x10 to the -1
what is an energy level
shells
electrons are held in orbit because they are attracted to the positive nucleus
how can an electron move to a different shell
if it absorbs EM radiation with the right amount of energy
when it moves up it is said to be excited
the electron will then quickly fall back to its original energy level and in doing so will emit the same amount of energy it absorbed
the energy is carried away by EM radiation
discuss alpha particles
helium nucleus
two protons and two neutrons
they don’t penetrate far into materials and are stopped quickly - they can only travel a few cm in air and are absorbed by a thin sheet of paper or skin
because of their size they are strongly ionising
discuss a beta- particle
a fast moving electron released by the nucleus have virtually no mass they are very tiny stopped by aluminium medium ionising
discuss gamma rays
EM wave not a particle speed is 3x10 to the power of 8 m/s penetrate km stopped by lead or concrete least ionising
what happens to an atom when it emits a alpha particle
mass number decrease by 4
atomic number decreases by 2
what happens to an atom when it emits a beta minus particle
mass number doesn’t change
atomic number increases by 1
what happens to an atom when it emits a beta plus - position
mass number doesn’t change
atomic number decreases by 1
what happens to an atom when it emits a gamma ray
mass and atomic number don’t change
what is half life
how long it takes for half of the radioactive atom to decay
what is contamination
when a radioactive particle gets into an object
what is irradiation
exposure to radiation
write the nuclear equation from
600
X
100
596 4
Y + alpha (α)
98 2
this is alpha decay
write the nuclear equation for beta minus decay
596
Y
95
596 0
Z + e
99 -1
the e may also be written with a B because a beta minus and electron are the same
write the nuclear equation for beta positive decay
18
F
9
18 0
O + B
8 1
the eight at the bottom makes it oxygen even if the top number isn’t 16
write the nuclear equation for neutron emission
13
Be
4
12 1
Be + n
4 0
when a neutron leaves the nucleus
what is the nuclear equation for gamma emission/radiation
60
A
30
60
B + gamma
30
the mass and charge stay the same because gamma isn’t a particle
why is alpha the most ionising
because it is 2+ charge and is big and slow so when it moves past an atom it will easily attract the electrons pull out of orbit
why is beta the middle amount of ionising
will push the electrons out of orbit because it is negative like the electron so It will repel the electrons and push them off the shell
but it has to be more precise than alpha because it is smaller and faster
why is gamma the least ionising
because it needs a lot of energy to give the electron enough energy to leave the shell and orbit
displacement
the distance from start to finish in a straight line in the most direct route
what is newtons first law
an object will remain stationary until it is affected by an external force
