CM-UY 1004 Lecture Notes - Lecture 11: Pauli Exclusion Principle, Hmu Language, Magnetic Quantum Number

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23 Oct 2017

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Planck: energy can only be absorbed or released from atoms in certain amounts called. Photoelectric effect: electrons are ejected from the surface of certain metals exposed to light of at least a minimum frequency called threshold frequency. Light has wave nature and particle nature. All elements have different line spectrums (mix of lines -- colors) Can only have specific (quantized energy values. Heisenburg"s uncertainty principle: on the mass scale of atomic particles, we can"t. For electrons: we cant determine momentum and position simultaneously. If x is the uncertainty in position and mv is the uncertainty in momentum then x mv h. Shrodinger proposed equation containing both wave and particle terms. Solving equation wave functions shape of electronic structures. Size and energy of the orbital/distance of e - . No 2 electrons in an atom can have the same 4 quantum numbers. Shell: electrons with same value of n.

Related Questions

Background:

Electrons are emitted from the surface of a metal when it's exposedto light. This is called the photoelectric effect. Each metal has acertain threshold frequency of light, below which nothing happens.Right at this threshold frequency, an electron is emitted. Abovethis frequency, the electron is emitted and the extra energy istransferred to the electron.

The equation for this phenomenon is

KE = hv - hv_0

where KE is the kinetic energy of the emitted electron, h= 6.63times 10^{-34}J * s is Planck's constant, v is the frequency of thelight, and v_0 is the threshold frequency of the metal.

Also, since E = hv, the equation can also be written as

KE = E - E_0

where E is the energy of the light and E_0 is the threshold energyof the metal.

Question:

Here are some data collected on a sample of cesium exposed tovarious energies of light.

Light energy
eV Electron emitted? Electron KE
eV
3.87 no â
3.88 no â
3.89 yes 0
3.90 yes 0.01
3.91 yes 0.02

Part A
What is the threshold frequency v_0 of cesium?

Note that 1eV (electron volt) = 1.60\times 10^{-19}~J.
Express your answer in hertz. v_0 = ___________Hz

LIGHT LAB SPRING 2018 CHEM 1430 Ill. Quantization of Electromagnetic Radiation In 1894, the German physidist, Max Plank, was working for a utility company to maximize visible light output from incandescent lamps using minimum power. Based on theoretical considerations, Planck postulated that electromagnetic energy could only be emitted at discrete values, rather than the continuum of predicted by classical physics, as multiples of the frequency of the radiation. Planck's Postulate took the mathematical form: EÂ·hv where the energy emitted, in Joules, is the product of a constant, h, known as Planck's Constant, and the frequency of the radiation, v. Planck's Postulate was experimentally verified and h found to have the value of 6.626 x 1034 Js(Joule seconds). The idea that electromagnetic radiation energy had specific frequency dependent energy was termed a "quantum of action," a distressing finding for the dlassically trained Planck. Despite his objections, Planck adopted this quantization of energy as a last resort to reconcile experiment with theory. This discovery set the stage for the early understanding of atomic structure, led to the term "photon" to describe the packet of energy carried by light waves, led to an understanding of the photoelectric effect, eventually leading to the development of general quantum theory Planck's Relationship, in combination with the tight equation, c the energy of a photon from frequency or wavelength. Î» w, allow expressions to be written to calculate ACTIVITY 4: QUANTIZATION OF THE ENERGY OF RADIATION To practice cakculations with Planck's Relationship, complete the following table, showing work with units in the right mest column, Convert given frequency to energy or given wavelength to energy. Take the value for Planck's Constant, h, to be 6.626 x 10"Js, show a calculation string include dimensions, reporting the final value to the proper number of significant figures Spectral Region Wavelength Frequency Energy in J/photon Show Calculation String Î» in meters v in s or cps X-ray 6.0 x 10"m Blue light 4.5 x 10m Infrared 4.1 x 10" cps Microwave 7.3 x 101 cps Radio Wave 3.0x 10 m IV. Bohr's Quantum Model for the Hydrogen Atom Ernest Rutherford's Gold Foil Experiment of 1911 demonstrated the nuclear structure of the atom. Questions remained as to how electrons were arranged in the atom. The most common belief called for the negatively charged the late 19h century recognized a particle (an electron) traveling around a body (the positively charged nucleus) would continuously radiate energy, slowing over time, eventually falling into the nucleus. Matter would collapse. Page 8 of 12

CM-UY 1004 Lecture Notes - Lecture 11: Pauli Exclusion Principle, Hmu Language, Magnetic Quantum Number

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