first to propose idea of atom

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

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