first to propose idea of atom democritus. wrote out the first four point atomic theory dalton

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.

• 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.

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

first to propose idea of atom democritus. wrote out the first four point atomic theory dalton

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