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Chem unit 4
Question | Answer |
---|---|
Democritus | Ancient Greek who first came up with idea of atoms, derived from atomos which means indivisible |
John Dalton | All elements composed of atoms (indivisible), atoms of same element the same, atoms of different element different, compounds contain atoms of more than 1 element, compounds always form the same way |
Why was John Dalton's theory accepted? | had experiments and data to support theory |
J.J. Thomson | cathode ray tube experiment, discovered electron, plum pudding theory |
Ernest Rutherford | gold foil experiment, discovered the nucleus, the nuclear atom |
Niels Bohr | electrons exist at certain energy lvls, live in orbitals |
electron cloud theory/model | electrons move in less predictable manner, electron cloud represents most likely electron locations, describes possible locations |
energy levels (how can electrons move between them?) | add energy = electron move up lvl, take away energy = electron move down lvl |
ground state | electron configuration when all electrons have lowest possible energies, most stable configuration |
excited state | when electrons temporarily occupies energy state greater than ground state, eventually returns to ground state |
orbitals | region of space around nucleus where electron is likely to be found |
# of electrons each orbital can hold | lvl 1=2; lvl 2=8; lvl 3=18; lvl 4=32 |
parts of atom | nucleus, proton, electron |
parts of atom charges | nucleus=none; proton=positive; electron=negative |
isotope | atoms of same element that have diff # of neutrons/different mass numbers |
avg atomic mass | [% (in decimal) x mass] + [% (in decimal) x mass] |