molecule●The addition of hydrogen is a type of reaction known as hydrogenation, and results in the hydrocarbon becoming saturatedChem Unit #2: Structure and Properties of MatterEarly Atomic Theories and the Origins of the Quantum TheoryEarly Atomic TheoriesDalton -> Thomson’s -> Rutherford’s -> Bohr’s -> Quantum MechanicalDalton - described matter as being composed of small spheres called atomsThomson - cathode ray tube experiment
- atoms are + charged masses with - charged particles - plum pudding modelRutherford- gold foil experiment- large deflection of particle lead Rutherford to believe that an atom has a + charged nucleusLimitations of Rutherford’s Model-Since he predicts that electrons are constantly orbiting the nucleus, they should be accelerating, and therefore emit photons of electromagnetic radiation-Because the atom emits a photon, it should be losing energy, therefore the orbit of the electron would quickly decay into the nucleus and the atom would be unstableThe Bohr Model Spectroscopy- studies atomic spectra-You can tell a lot about atoms by their light spectra-Electrons jump between energy levels and release energy (in the form of photons) as they fall back down to ground state-Electrons release packets of light (not a continuous stream) - we see the colours in distinct linesBohr’s Model-Bohr studied the line spectra of hydrogen and, based on his observations, came up with his model-His model calculated the wavelengths of the possible energies of photons that could be emitted from an excited hydrogen atom-Limitations: it could only explain single-electron systems-Bohr wanted to prove his model wrong, which is why we acknowledge him - he focused on what worked and what didn’t work with his modelThe Quantum Mechanical ModelQuantum mechanical model of the atom-Incorporates an electron acting as a standing “wave” not just a “particle”Heisenberg’s Uncertainty Principle-It is impossible to know, with perfect accuracy, both the location and speed of an electron. It is impossible to determine accurately both the position and the direction and the speed of a particle at the same instantOrbitals●An atomic orbital is the region of space where an electron spends 90% of its time; depicted by a sphere●An atomic orbital is a framework with no defined boundary●The higher the density of the cloud, the greater the possibility of finding an electron at that point●How electrons move within an orbital is a mysteryElectrons are Described Using 4 Quantum NumbersNameSymbolAllowed ValuesPropertiesPrincipal Quantum Numbern0 to ∞-Energy level. -Larger the n value, larger the sizeOrbital Angular Momentum Number l0 to (n-1)Orbital shapeI=o (orbital s)
(Orbital Shape)I=1 (orbital p)I=2 (orbital d) I=3 (orbital f)Magnetic Quantum Numberml-l to +lOrbital orientationElectron Spin Quantum Numberms+½ or -½ SpinPauli Exclusion Principle - no two electrons can have the same 4 quantum numbers-This is due to the spin of the electronElectron Configuration
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