First to propose idea of atom
Democritus
Wrote out the first four point atomic theory
Dalton
Found the e-
Thomson
Experimented with cathode ray tubes
Thomson and Goldstein
Thomson’s plum pudding
Found the electrical charge of the e-
Millikan
Did the oil drop experiment
Millikan
Did the gold foil experiment
Rutherford
Found the proton
Goldstein
Found the nucleus
Rutherford
Found the neutron
Chadwick
Atomic Theory Polka
• Dalton, Thomson, Rutherford and Bohr. Schrödinger and Heisenberg, and many, many more. Used their brains to venture in the realm of inner space and found the world of the atom was a weird and wondrous place.
• Dalton did experiments and said, “I think it’s clear, atoms are tiny indestructible spheres.”
• Thomson worked with cathode rays and said, “I disagree. A plum-pudding model makes much more sense to me.” A new chapter in atomic theory started to unfold.
• When Rutherford played around with atoms made of gold. When a few of his alpha particles came bounding back, he hypothesized a nucleus had knocked them off the track.
• Dalton, Thomson, Rutherford and Bohr. Schrödinger and Heisenberg, and many, many more. Used their brains to venture in the realm of inner space and found the world of the atom was a weird and wondrous place.
• Bohr saw spectral lines for hydrogen and said, “It seems to me.. Electrons move in orbits with specific energies.”
electron
neutron
proton
• Heisenberg said, “Forget it, there’s no way to know the orbit or a path, where the electron’s gonna go.”
• Schrödinger used lots and lots of fancy mathematics, and made a model of the atom based on quantum mechanics. It has orbitals and those are based on probability. The atom is a fuzzy blob of pure uncertainty.
• Dalton, Thomson, Rutherford and Bohr. Schrödinger and Heisenberg, and many, many more. Used their brains to venture in the realm of inner space and found the world of the atom was a weird and wondrous place.
What do you know about What do you know about atom?atom?
How Atoms DifferHow Atoms Differ
Date:Date:
Subatomic ParticlesSubatomic Particles PROTONSPROTONS pp++
In the nucleusIn the nucleus +1 charge+1 charge 1 amu1 amu
ELECTRONELECTRON ee--
In electron cloudIn electron cloud -1 charge-1 charge 11//18401840 amu amu
NEUTRONNEUTRON nnoo
In the nucleusIn the nucleus No chargeNo charge 1 amu1 amu
Atomic numberAtomic number
Used to arrange elements in PT by Used to arrange elements in PT by MosleyMosley
# of PROTONS# of PROTONS
# of ELECTRONS # of ELECTRONS IFIF an ATOM an ATOM
IsotopesIsotopes
Atoms of the same element that differ in Atoms of the same element that differ in the # of neutronsthe # of neutrons
Atomic MassAtomic Mass
The The weightedweighted average of all isotopes. average of all isotopes. Always a decimal (unless a man-made Always a decimal (unless a man-made
element)element)
Mass numberMass number
Mass of an isotopeMass of an isotope AlwaysAlways a whole number – a whole number – not on PTnot on PT # of PROTONS + NEUTRONS# of PROTONS + NEUTRONS
NuclideNuclide Tells atomic # and mass # of an atomTells atomic # and mass # of an atom
23231111NaNa
Sodium-23 has ____ protons, ___ electrons Sodium-23 has ____ protons, ___ electrons and ____ neutronsand ____ neutrons
PracticePractice
32321616SS
28281414SiSi
141466CC
IonsIons Atoms with a chargeAtoms with a charge
CATIONSCATIONS
Cations are pawsitive and are written Cations are pawsitive and are written with a plus charge on the upper right.with a plus charge on the upper right. LOST an e-, have more protons; therefore LOST an e-, have more protons; therefore
positive.positive. Charge indicates the number of electrons Charge indicates the number of electrons lostlost..
Hint: cation has a Hint: cation has a tt which looks like which looks like ++
ANIONSANIONS
Anions are negative and written with a Anions are negative and written with a negative charge on the upper right.negative charge on the upper right. GAINED an e-, have more electrons; GAINED an e-, have more electrons;
therefore negative.therefore negative. Charge indicates number of electrons Charge indicates number of electrons gained.gained.
36361717ClCl--
_____ protons _____ neutrons _____ protons _____ neutrons _____ electrons_____ electrons
PracticePractice
161688OO-2-2
1081084747AgAg++
80803535Br Br --
2072078282PbPb+4+4