atomic structure

Cards (17)

What did John Dalton think an atom was ?
a simple sphere of charge
what did JJ Thompson discover ?
electrons are embedded in the atom - plum pudding model
what did Rutherford's alpha scattering experiment discover ?
most atoms past through the gold sheet but some deflected meaning there had to be a positive charged nucleus.
what di Neil's Bohr discover ?
that electrons orbit the nucleus on shells set distances away
what did James Chadwick discover ?
the neutron
what is an isotope ?
an element with the same number of protons but different neutrons
what happens to unstable isotopes ?
they decay into other elements and become radioactive.
describe alpha radiation
-emitted from nucleus
-have 2 neutrons and 2 protons (helium nucleus)
-absorbed by paper
-strongly ionising
describe beta radiation
-fast moving electron
-absorbed by aluminium
-a neutron turns into a proton
describe gamma radiation 
-wave of radiation
-absorbed by lead and concrete
-weakly ionising
what is a half life ?
the time taken for the amount of radiationto half
what is decay like ? 
random
what is irradiation ?
exposure to radiation
does irradiation something make it radioactive ?
no
what causes contamination ?
radioactive particles get onto something
which radiation is most dangerous ?
beta and gamma
when is alpha the most dangerous ?
inside the body