atomic and nuclear physics Flashcards
the plum pudding model
JJ Thompson founded the electrons
atoms have a positive charge
electrons are dotted through the atom
positive charge is spread through the atom
rutherford alpha particle scattering experiment
it involved firing beams of alpha particles at a thin sheet of gold foil. the final location of the alpha particles could then be measured using an alpha detector placed in different positions around the gold foil
observations of alpha particle scattering experiment
make alpha particles traveled straight through
some were deflected by a small angle
a small number of alpha particles were back scattered
rutherford model of the atom
-atom has a central positively charged nucleus
-nucleus contains protons and electrons orbiting the nucleus
-all the mass of an atom is contained in the nucleus
why are atoms neutral
they have an equal number of protons and electrons
charge mass and position of proton
+1, 1, in the nucleus
charge mass and position of neutron
0, 1, in the nucleus
charge mass and position of electron
-1, 1/1840, orbiting nucleus in shells
what’s the mass number
the number of protons and neutrons
what’s the mass number symbol
A
atomic number definition
the number of protons
atomic number symbol
z
what’s an isotope
same atomic number different mass number
OR
in the nucleus there will be the same number of protons but different number of neutrons
what is radioactivity
some nuclei are unstable and will disintegrate by letting alpha beta or gamma radiation randomly and spontaneously
what’s the nature of an alpha particle
helium nucleus(2 protons and 2 neutrons)
charge of an alpha particle
+2
mass of an alpha particle
4
what’s an alpha particle stopped by
few cm of air
paper
alpha symbol
4
H
2
nature of a beta particle
electron