electronic behavior of atoms. lo describe how light is created. explain how wavelengths of light...

Chapter 1 Section 5

Electronic Behavior of Atoms

January 27, 2012HW: 1.4 CTG p. 43 #1-11 (Due Wed)

LODescribe how light is created.Explain how wavelengths of light

relate to energy levels in the atom.

SCView the spectrum of hydrogen.Interpret changes in electron

energies in the hydrogen atom to develop an explanation for where the colored light in the hydrogen spectrum comes from.

Use Bohr’s model of the atom to predict parts of the hydrogen-atom spectrum.

Compare the wavelengths, energies, and frequencies of light of different colors.

Identify regions in the electromagnetic spectrum.

Explain the photoelectric effect.

Do NowGrade 1.4 QuizCopy LO and SCWDYS, WDYT p. 35

AgendaWDYS, WDYTInvestigationChem TalkSummary

Investigate

Read through and complete numbers 1 and 2You MUST draw diagrams with what you see that include the colors

Investigation

Complete numbers 3 and 4 on pg. 36Be ready to discuss as a class!

Investigation

Complete numbers 5-9, reading through each of the explanations and answering the questions.Pay close attention to the diagram on p. 38

Date:HW: CTG p. 43 #1-11

LODescribe how light is created.Explain how wavelengths of light

relate to energy levels in the atom.

SCView the spectrum of hydrogen.Interpret changes in electron

energies in the hydrogen atom to develop an explanation for where the colored light in the hydrogen spectrum comes from.

Use Bohr’s model of the atom to predict parts of the hydrogen-atom spectrum.

Compare the wavelengths, energies, and frequencies of light of different colors.

Identify regions in the electromagnetic spectrum.

Explain the photoelectric effect.

Do NowCopy LO and SCWDYS, WDYT p. 35

AgendaWDYS, WDYTInvestigationChem TalkSummary

Chem Talk

Skim through the chem talk on p. 39Do not take notes!

http://player.discoveryeducation.com/index.cfm?guidAssetId=0D2CCF17-8C4E-4101-A1FF-D11305F6878C

Watch first 5 minutes

Chem Notes

Who was Niels Bohr?

What did he discover?

Chem Notes

Who was Niels Bohr?

What did he discover?

A Danish Physicist

He thought that electrons took a circular orbit around an atom and that they jump between energy levels while taking in energy and forming light

From Bohr’s Model

Chem Notes

What is light

What is frequency?

Chem Notes

What is light

What is frequency?

Photons, or packets of energy, that travel in waves.Come from energy level transfers

Chem Notes

What is light

What is frequency?

Photons, or packets of energy, that travel in waves.Come from energy level transfers

The number of cycles per second, measured in Hz usually

Chem Notes

What is wavelength

What is the speed of light?

Chem Notes

What is wavelength

What is the speed of light?

The distance from crest to crest in a wave.

Chem Notes

What is wavelength

What is the speed of light?

The distance from crest to crest in a wave.

3x108 m/s, and it is constant!

Wave Diagram

Chem Notes

How do we calculate frequency using wavelength?

Chem Notes

How are wavelength and energy related?

Chem Notes

How are wavelength and energy related?

They are inversely related!

As E increases, the wavelength gets smaller!

Chem Notes

What are photons?

How can we calculate frequency from energy?

Chem Notes

What are photons?

How can we calculate frequency from energy?

Fixed packets of energy with a specific wavelength.

Chem Notes

What are photons?

How can we calculate frequency from energy?

Fixed packets of energy with a specific wavelength.

Where h is plancks constant: 6.63x10-

34 Js

Chem Notes

What is the photoelectric effect?

Chem Notes

What is the photoelectric effect?

When light collides with an atom, it interacts with an electron, causing it to be thrown off of the atom due to the fixed amount of energy of the photon.

Chem Notes

What were the weaknesses of the Bohr Model?

Chem Notes

What were the weaknesses of the Bohr Model?

1. It could only account for the light transitions of the Hydrogen atom

2. Could not explain why some transitions were allowed while others were not.

Practice Problem

What is the frequency of light that has a wavelength of 432.4nm?

Practice Problem

Using Planck’s constant, what is the energy of red light?

Practice ProblemIn hydrogen the energy change of an electron jumping from E3 to E2 is 3.03 x 10-19 J

What is the frequency?

What is the wavelength? (and therefore color)

Chem Talk

Complete the checking up questions.

Summary

Essential Questions, p. 42--How do you know?--Why do you believe--Why should you care

LO and SC reflection