particles and radiation Flashcards
what’s the relative mass of an electron?
0.0005
what’s the atomic number?
number of protons in the nucleus, has the symbol Z.
the number that defines the element
what’s the nucleon number?
also called the mass number
has the symbol A
tells you how many protons and neutrons there are in the nucleus.
what’s the specific charge of a particle?
the ratio of its charge to its mass
what are isotopes?
atoms with the same number of protons but different number of neutrons
what’s isotopic data?
the relative amounts of the different isotopes of an element present in a substance.
what are all the forces that act on the nucleons in a nucleus.
electromagnetic
gravitational
strong nuclear
what does the electromagnetic force do in the nucleus of atoms?
causes the positively charged protons to repel from each other
what does the gravitational force do in the nucleus of atoms?
causes all the nucleons in the nucleus to attract each other due to their masses
why is the strong nuclear force needed to act on nucleons in the nucleus?
the repulsion from the electromagnetic force is much bigger than the gravitational attraction so there must be another force to hold the nucleus together.
what have experiments shown of how the strong nuclear force changes with distance and between different nucleons?
it has a very short range
it’s repulsive at distances smaller than 0.5fm to stop it crushing the nucleus.
becomes attractive past 0.5fm
it then reaches maximum attractive value and then falls rapidly towards 0 after 3fm
it works equally between all nucleons
what is nuclear decay?
when unstable nuclei emit particles to become more stable
what size atoms does alpha decay occur in?
very big atoms, more than 82 protons.
because they are too big for the strong nuclear force to keep them stable
how far can alpha particles travel in air?
only a few cm
how could you test the range of an alpha particle?
observing the tracks left behind in a cloud chamber
or use a Geiger counter or a spark counter by changing the distance it is from the alpha source
what is beta decay?
the emission of an electron from the nucleus along with an antineutrino
when does beta decay occur?
if isotopes are neutron rich. when a nucleus ejects a beta particle, one neutron is turned into a proton
how far can a beta particle travel in air?
several metres
name the 7 types of electromagnetic radiation in order of increasing frequency
radio waves, microwaves, infrared, visible light, UV, X-rays, gamma rays
name the 7 types of electromagnetic radiation in order of increasing wavelength
gamma rays, X-rays, UV, visible light, infrared, microwaves, radio waves
what happens to the energy of electromagnetic radiation as frequency increases?
energy increases
what is an antiparticle?
a particle with the same mass and rest energy but with opposite charge
what’s pair production?
when energy is converted into mass, you get equal amounts of matter and antimatter.
only occurs if there’s enough energy to produce the masses of the particles
always produces a particle and its corresponding antiparticle
what’s the minimum energy needed for pair production?
the total rest energy of the particles that are produced.
this is all the energy that would be produced if all its mass was transformed into energy