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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