CHEM101 Lecture Notes - Lecture 5: Matter Wave, Electromagnetic Spectrum, Photon

20 views3 pages

raspberryminnow639

19 Sep 2015

School

University of Alberta

Department

Chemistry

Course

CHEM101

Professor

Sai Yiu

For unlimited access to Class Notes, a Class+ subscription is required.

robinyellowson and 40146 others unlocked

CHEM101 Full Course Notes

Verified Note

77 documents

Document Summary

Chem 101 lecture #5 electrons as particles and waves. Let einitial = energy at initial stage n=3 n=2. E = ? n=1: e = ef - ei = (-2. 178 10-18 j) z2( z2. For hydrogen, when n = 1 the electron is at its ground state: when (n= 2,3,4 ) the electron is at its excited state. Work example: calculate the energy of the photo absorbed or emitted in the transition n = 4 to n = 2 for a hydrogen atom. E = -2. 18 10-18 j 12. = -2. 18 10-18 j (0. 1875) = -4. 09 10-19 j = energy is emitted. E = hc (6. 626 10 34 j s) (3. 00 109) (6. 626 10 34 j s) (3. 00 109 m/ s) The bohr"s equation can be used for finding the ionization fo an atom. What is the ionization energy involved when one mole of hydrogen atom at its ground state was excited to infinity? (avogadro"s number = 6. 022 1023 mol)

Related Questions

1. An atom, X, has a ground state binding energy(energy necessary to eject electron from the ground state) of 2.179e-18 J. The line(emission) spectrum for atom X is shown with n=2 to n=1(121.57 nm), n=3 to n=1(102.57 nm), n=4 to n=1(97.254 nm), n=5 to n=1(94.974 nm),and n=6 to n=1(93.780 nm). For each of the emission lines(given as wavelengths in nm), the final state is the ground state, or lowest energy state, of the atom.

a. What is the energy of the third excited state of X?

b. What is the energy of the highest energy state of X that is necessary to account for the emission spectrum?

c. Is it possible for an electron in the ground state of atom X to absorb light of energy 3.03e-19 J? Why or why not?

d. Can atom X emit light of energy 3.03e-19 J? If so, what are the initial and final states of such a transition?

e. Is it possible for X to absorb light of energy 2.5e-18 J? Why or why not?

Help please

1. Theabsorption spectra of ions have been used to identify the presenceof the elements in the atmospheres of the sun and other stars. Whatis the wavelength of light (in nm) that is absorbed byHe⁺ ions, when an electron is excited from the Bohrorbit with n = 2 to the n = 7 state? The energy of an electron inthe nth level is

E_n =

BZ²

n²

where B = 2.18 x 10^-18 J and Z = charge onnucleus (number of protons).

2. Anelectron in the 4^th energy level of the H atom drops tothe 1^st energy level. In other words an excited electrondrops to the ground state. What is the energy (in J) of the emittedphoton)? The energy of an electron in the nth level is

E_n =

n²

2.18 x 10^-18 J

n²

3.The photoelectric effect for a certain alloy has a thresholdfrequency of 8.40 x 10¹⁴ Hz. For light of thisfrequency, find the energy of one mole of photons (inkJ).