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Atomic Theory and Its Applications
Sep 10, 2024
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Lecture Notes on Atomic Theory and Related Topics
Topics Covered
Atomic Theory
Mass Spectroscopy
Mole Conversions
Electron Configuration
Photoelectron Spectroscopy
Periodic Trends
Atomic Theory
Focus on tungsten (W), atomic number 74.
Atomic mass: 183.84 amu.
Molar mass: 183.84 g/mol.
Atomic Number
: Number of protons; does not change.
Tungsten has 74 protons.
Average Atomic Mass vs. Molar Mass
:
AMU measures mass of a single atom.
Molar mass measures mass of one mole.
1 mole = Avogadro's number (6.02 x 10^23 atoms).
Isotopes
:
Stable isotopes of tungsten: 182, 183, 184, 186.
Example problem: Finding protons, neutrons, and electrons in W-183.
Protons = 74, Electrons = 74, Neutrons = 109 (since 183 - 74 = 109).
Mass Spectroscopy
Analyzes the atomic structure by looking at protons, neutrons, and electrons.
Example using tungsten isotopes.
Remainder percentage calculation for isotopes.
Graphing mass-to-charge ratio vs. abundance.
Mole Conversions
Discussion on determining which compound has more tungsten atoms.
Compare WO3 vs. WO2.
Molar mass is key to determining the number of moles (atoms).
Empirical Formula
Example: Combustion of tungsten with oxygen.
Determine formula from mass data: W + O2 -> WO2.
Empirical formula calculation based on mole ratios.
Electron Configuration
Key Vocabulary
:
Orbital: Region in space with up to two electrons.
Energy Level: Distance of electron from nucleus.
Sublevel: Shape of the orbital (s, p, d, f).
Electron Spin: Opposite spins in same orbital.
Sublevel Shapes
:
s: Sphere
p: Dumbbell
d: Four-leaf clover
f: Complex (flower-like)
Block Method
: Using periodic table blocks to determine electron configuration.
Example: Nitrogen (N) - 1sĀ² 2sĀ² 2pĀ³.
Photoelectron Spectroscopy
:
Graphs showing electron configurations.
Peaks represent electron amounts in sublevels.
Closer peaks have higher ionization energy.
Periodic Trends
Atomic Radius: Half the distance between two identical nuclei.
Ionization Energy: Energy to remove an electron.
Higher energy means harder to remove.
Electron Affinity: Energy released when atom gains electron.
Smaller atoms release more energy.
Electronegativity: Atom's ability to attract electrons in a bond.
Critical for understanding bond types.
Trends Summary
Atomic Radius increases down and to the left.
Ionization Energy, Electron Affinity, Electronegativity increase up and to the right.
Trends depend on electron distance and nuclear charge.
Q&A Highlights
Discussion on reading and interpreting photoelectron spectroscopy graphs.
Isoelectronic elements and their spectral similarities.
Conclusion
Overview of unit structure on these topics and transition into quantum mechanics and electron behavior.
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