I. Structure of the Atom The Early Models of the Atom.

I. Structure of the AtomI. Structure of the Atom

The Early Models of the AtomThe Early Models of the Atom

LawsLaws Law of Conservation of MassLaw of Conservation of Mass Law of Definite /Constant Proportion-Law of Definite /Constant Proportion- compounds have a compounds have a

________ composition.________ composition.

Carbon tetrachloride is always 1 atom carbon per 4 Carbon tetrachloride is always 1 atom carbon per 4 atoms chlorine.atoms chlorine.

They react in specific ratios by mass.They react in specific ratios by mass. Law of Multiple Proportions-Law of Multiple Proportions- When two elements form When two elements form

more than ______compound, the ratios of the masses of more than ______compound, the ratios of the masses of the second element that combine with one gram of the first the second element that combine with one gram of the first can be ______ to small whole numbers.can be ______ to small whole numbers. The ratio of the masses of oxygen in HThe ratio of the masses of oxygen in H22O and HO and H22OO22 will will

be a small whole number (“2”).be a small whole number (“2”).

Dalton’s Atomic TheoryDalton’s Atomic Theory1)1) Elements are made up of _________Elements are made up of _________

2)2) Atoms of each element are _______. Atoms of each element are _______. Atoms of different elements are different.Atoms of different elements are different.

3)3) Compounds are formed when atoms Compounds are formed when atoms combine. Each compound has a specific combine. Each compound has a specific _______ and ______ of atom._______ and ______ of atom.

4)4) Chemical reactions are ________ of Chemical reactions are ________ of atoms. Atoms are not _____ or destroyed.atoms. Atoms are not _____ or destroyed.

Plum Pudding ModelPlum Pudding Model J.J. Thomson is credited with the discovery J.J. Thomson is credited with the discovery

of the electronof the electron

_______ Experimentation→ e-/m _______ Experimentation→ e-/m ratioratio

_______ Experimentation→e- Charge_______ Experimentation→e- Charge

Thomson’s ExperimentThomson’s Experiment

Voltage source

+-

Thomson’s ExperimentThomson’s Experiment

Voltage source

+-

Passing an electric current makes a beam Passing an electric current makes a beam appear to move from the _____ to the appear to move from the _____ to the _____ end._____ end.

Thomson’s ExperimentThomson’s Experiment

Voltage source

+-

Voltage source

Thomson’s ExperimentThomson’s Experiment

By adding an electric field By adding an electric field

Voltage source

Thomson’s ExperimentThomson’s Experiment

By adding an electric field, he found that By adding an electric field, he found that the moving pieces were __________the moving pieces were __________

+

-

Thomson’s ModelThomson’s Model Found the electron.Found the electron. Couldn’t find positive Couldn’t find positive

(for a while). (for a while). Said the atom was like Said the atom was like

---------.---------. A bunch of positive A bunch of positive

stuff, with the ______ stuff, with the ______ able to be removed. able to be removed.

Millikan’s ExperimentMillikan’s Experiment

Oil

Atomizer

Oil droplets

Telescope

-

+

Millikan’s ExperimentMillikan’s Experiment

X-rays

_______ give some electrons a charge.

Millikan’s ExperimentMillikan’s Experiment

Some drops would hover

From the m of the drop and the charge on the plates, he calculated the ___________

Rutherford’s ExperimentRutherford’s Experiment Used------- to produce alpha particles (+ Used------- to produce alpha particles (+

charged particles).charged particles). Aimed alpha particles at gold foil by Aimed alpha particles at gold foil by

drilling hole in ----- block.drilling hole in ----- block. Since the mass is evenly distributed in Since the mass is evenly distributed in

gold atoms alpha particles should go ------- gold atoms alpha particles should go ------- through.through.

Used gold foil because it could be made Used gold foil because it could be made atoms thin.atoms thin.

Lead block

Uranium

Gold Foil

Florescent Screen

What he expected

Because

Because, he thought the mass was evenly distributed in the atom.

What he got

How he explained it

+

Atom is mostly _____Atom is mostly _____ Small dense,Small dense,

_______ piece_______ pieceat center.at center.

Alpha particlesAlpha particlesare ______ byare ______ by

it if they get closeit if they get close enough.enough.

+

Modern ViewModern View The atom is mostly empty space.The atom is mostly empty space. ------ regions------ regions Nucleus- protons and neutrons.Nucleus- protons and neutrons. Electron cloud- region where you might Electron cloud- region where you might

find an -------.find an -------.

The Mass and Change of the The Mass and Change of the Electron, Proton, and NeutronElectron, Proton, and Neutron

Particle Mass (kg) Charge

Electron 9.11 10 31 1

Proton 1.67 10 27 1+

Neutron 1.67 10 27 0

Sub-atomic ParticlesSub-atomic Particles ___- atomic number = number of protons ___- atomic number = number of protons

determines type of atom.determines type of atom. ___ - mass number = number of protons + ___ - mass number = number of protons +

neutrons.neutrons. __________ = number of electrons if __________ = number of electrons if

neutral.neutral.

SymbolsSymbols

XA

Z

Na23

11

Niels Bohr Atomic ModelNiels Bohr Atomic ModelFixed Orbits, Predictable PathsFixed Orbits, Predictable Paths

Derived from Max Planck’s description of light packets or quanta called Derived from Max Planck’s description of light packets or quanta called photonsphotons

THE QUANTUM MECHANICAL MODELTHE QUANTUM MECHANICAL MODEL1924-Louis DeBroglie applied ____________to model1924-Louis DeBroglie applied ____________to model1927-Erwin Schrodinger applied wave equation to model1927-Erwin Schrodinger applied wave equation to model Heinsberg’s Principle said speed and position cannot be calculated at same timeHeinsberg’s Principle said speed and position cannot be calculated at same time

TOO MUCH BRAINPOWER IN ONE PLACETOO MUCH BRAINPOWER IN ONE PLACEThe Atomic TheoristsThe Atomic Theorists