where is the atomic mass of an element found
the top number
where is the atomic number of an element found
the bottom number
protons charge?
+1
neutrons charge?
0
electrons charge?
-1
what is an ion
an atom that has gained or lost electrons
what did dalton discover
all elements are composed of indivisible, small particles(atoms)
what did jj thompson discover
the electron
what did rutherford discover
alpha and beta rays
what did bohr discover
that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element