7 - Atomic, nuclear and particle Flashcards
What did Rutherford’s experiment show?
the atom is mostly empty space
the mass of the atom is within the nucleus
deflected beam of particles must have approached positively charged region - the nucleus
volume of nucleus is very small
What are electron energy levels?
specific energies electrons in an atom can have
What causes an electron to be excited?
absorption of energy
What causes an electron to be relaxed?
emission of energy
What is the ground state?
13.6eV - the lowest energy level
What is the first excited state?
3.4eV
What is the second excited state?
1.5eV
What is the ionisation level?
0eV - the highest energy level, at which, the electron can escape the atom, forming an ion
What is activity?
the number of nuclear disintegrations per second
What is activity measured in?
Bequerels, Bq
What is alpha decay?
an element decays to produce a different element and an alpha particle, consisting of two protons and two neutrons
What is gamma radiation?
an EM wave emitted due to transitions in the nucleus
often accompanies alpha and beta decay
What is beta + decay?
a proton decays into a neutron, a positron and a neutrino
What is beta - decay?
a neutron decays into a proton, an electron and an anti-neutrino
What is beta?
a fast moving electron
What is an electron volt?
a unit of energy
KE electron gains by travelling across a pd of 1 volt
1eV = 1.6x10^-19C
What is the equation for energy gain?
energy gain = voltage x charge
What is half-life?
the time for half the radioactive isotopes to decay
What are quanta?
discrete packets of the EM spectrum
measurement of quantity
What are photons?
the smallest discrete amount of EM radiation
elementary particle
What is the energy carried by quantum?
E = hf h = Planck's constant 6.63 x 10^-34Js f = frequency
What is an electronvolt?
an alternative unit of energy
the KE electron gains travelling across a pd of 1 volt
What is the equation for energy gain?
E = VQ
What is strong force?
the force which exists within the nucleus to hold protons and neutrons together
What is the mass defect?
the difference between mass of the nucleus and mass of the individual particles