View source for PhET-Simulations-for-Chemistry/C3/Models-of-Hydrogen-atom/English


{|border=1
||'''Visual Cue'''
||'''Narration'''
|-
|| '''Slide Number 1'''

'''Title slide'''
|| Welcome to the spoken tutorial on '''Models of the hydrogen atom'''.
|-
|| '''Slide Number 2'''

'''Learning objectives'''
|| In this tutorial we will, 

Demonstrate '''Models of the Hydrogen Atom''', '''PhET simulation'''.
|-
|| '''Slide Number 3'''

'''System Requirements'''
|| Here I am using-

Ubuntu Linux OS v 14.04

Java v 1.7.0
|-
|| '''Slide Number 4'''

'''Pre-requisites'''
|| To follow this tutorial,

Learner should be familiar with topics in high school science.
|-
|| '''Slide Number 5'''

'''Learning Goals'''
|| Using this '''simulation''' we will,

Visualize different models of the hydrogen atom.

Explain the experimental predictions of each model.

Discuss limitations of each model.
|-
|| '''Slide Number 6'''

'''Learning Goals'''
|| Explain the energy level diagram.

Determine the orbital shape and orientation from n, l and m values.
|-
|| 
|| Let us start the demonstration.
|-
|| '''Slide Number 7'''

'''Link for PhET simulation'''

[http://phet.colorado.edu/ http://phet.colorado.edu]
|| Use the given link to download the '''simulation'''.

[http://phet.colorado.edu/ http://phet.colorado.edu]
|-
|| Point to '''Models of the Hydrogen Atom'''.
|| I have already downloaded '''Models of the Hydrogen Atom simulation''' to my '''Downloads''' folder.
|-
|| To open java file,

Press '''Ctrl+Alt+T''' keys.

Type '''cd Downloads''' and press '''Enter'''.
|| To run the '''simulation''', open the terminal.

At the prompt type '''cd space Downloads''' and press '''Enter'''.
|-
|| Type '''java hyphen jar hydrogen-atom_en.jar''' and press '''Enter'''.

Point to the interface.
|| Then type, '''java space hyphen jar space hydrogen hyphen atom_en.jar''' and press '''Enter'''.

'''Models of the Hydrogen Atom simulation''' opens.
|-
|| Point to '''File''' and '''Help'''.

|| Top-left corner of the screen has a menu bar with menu items '''File''' and '''Help'''.
|-
|| Point to '''Experiment''' and '''Prediction'''.
|| Below the menu bar, there is a grey button with two options, 

'''Experiment''' and

'''Prediction'''.
|-
|| Point to '''Experiment'''.
|| By default '''Experiment''' mode opens.
|-
|| 
Point to light gun.
|| On the screen, 

we see an experimental setup with a light gun to emit beam of photons.
|-
|| Point to '''Box of Hydrogen'''.

Point to zoom-in box.
|| There is also a '''Box of Hydrogen'''.

This box is filled with hydrogen atoms. 

The zoom-in box represents a single hydrogen atom.
|-
|| Point to '''Turn on the gun''' message.
|| A message appears.

It prompts you to click on the red button to turn on the light beam.
|-
|| Point to '''White''' and '''Monochromatic''' radio buttons.

Point to '''White''' radio button.
|| The light gun has two light controls, '''White''' and '''Monochromatic'''.

By default '''White''' light is selected.
|-
|| Click on '''Prediction''' button.

Point to '''Atomic Model''' panel.

Point to '''Classical''' and '''Quantum Atomic Models'''.
|| Click on '''Prediction''' option on the grey button. 

'''Atomic Model''' panel opens on the left side of the screen.

It has a list of '''Classical''' and '''Quantum Atomic Models'''.
|-
|| Cursor on the interface.
|| Here we can check how the prediction of a model matches the experimental results.
|-
|| Point to '''Legend''' box.
|| '''Legend''' box on the right-side of the screen has a list of sub-atomic particles.
|-
|| Point to slider at the bottom.

Point to '''Play'''/'''Pause''' and '''Step''' buttons.
|| At the bottom of the screen we have, 

* Slider to control speed of animation

* '''Play'''/'''Pause''' and '''Step''' buttons.

|-
|| Point to '''Billiard Ball''' model.

Click on '''Billiard Ball''' from the list.
|| The first model of atom proposed, is the '''Billiard Ball''' model.

By default '''Billiard Ball''' is selected from the list.
|-
|| '''Slide Number 8'''

'''Billiard Ball Model'''
|| '''Billiard Ball''' Model

'''Billiard Ball''' model is also called as '''Dalton's''' atomic model. 

It was proposed by '''John Dalton'''.

According to this model,

individual atom is visualized as solid, hard spheres, like billiard balls.
|-
|| Click on the red button of the light gun.

Point to '''White''' light.
|| Click on the red button of the light gun.

Select '''White''' light.
|-
|| Point to photons in zoom in box.
|| A beam of photons having different wavelengths pass through box of hydrogen.
|-
|| Point to deflected photons in the path of hydrogen atom.
|| Observe that,
All photons in the path of hydrogen atoms are deflected.
|-
|| '''Slide Number 9'''

'''Limitations of Billiard Ball Model'''

Experiments showed that atoms are mostly made up of empty space. 

Presence of different kinds of sub-atomic particles was also established.

|| Limitations of '''Billiard Ball''' model.

|-
|| '''Slide Number 10'''

'''Limitations of Billiard Ball Model'''

Sub-atomic particles carry positive and negative charges.

Based on these observations, Plum Pudding Model was suggested.
||Here are the limitations of '''Billiard Ball''' model.
|-
|| Cursor on the interface.

Click on the red button of light gun.

Click on '''Plum Pudding''' model.
|| Back to the '''simulation'''.

Turn off the light beam.

Click on '''Plum Pudding''' from the '''Atomic Model''' list.
|-
|| Point to model in zoom in box.

Point to brown mass.

Point to blue color particle.
This model was proposed by '''J. J. Thomson''' in 1904.
|| The positive charge is uniformly distributed and electrons are embedded into it.

The brown mass is the positive charge.

Blue colour particle in the middle is the electron.
|-
|| Click on '''Show spectrometer''' check-box.

Click on the red button of light gun.

Select '''White''' light.
|| Click on '''Show spectrometer''' check-box.

Turn on the light beam.

Select '''White''' light.
|-
|| Point to electron and deflected photons.

Point to spectrum.
|| When photons strikes electron, the electron moves and photons deflected.

Notice that, spectrum consists of only emitted uv photons.
|-
|| Click on the red button of the spectrometer.
|| Turn off the light beam.
|-
|| '''Slide Number 11'''

'''Limitations of Plum Pudding model'''

Gold foil scattering experiments by '''Rutherford''' showed that,

Positive charge is not spread evenly over the entire atom.
|| Limitations of''' Plum Pudding model'''

Here are the limitations of '''Plum Pudding''' model.
|-
|| Point to '''Classical solar system''' model of atom.
|| Based on the above observations,
Rutherford proposed the '''Classical solar system''' model of atom.
|-
|| '''Slide Number 12'''

'''Solar System Model'''
|| '''Solar System''' Model

Rutherford nuclear model of an atom is like a small scale solar system.

Nucleus plays the role of sun and the electrons that of revolving planets.
|-
|| '''Slide Number 13'''

'''Solar System Model'''
|| The very small positive charge portion of the atom was called nucleus.

Electrons move around the nucleus.

They move with very high speed in circular paths called orbits.
|-
|| Cursor on the interface.

Click on '''Pause''' button.

Click on '''Classical Solar System'''.
|| Back to the '''simulation'''.

Pause the '''simulation'''.

Click on '''Classical Solar System''' from the list.
|-
|| Point to '''Show electron energy level diagram'''.

Click on the check box.

Point to '''Electron energy level''' diagram.
|| Screen has '''Show electron energy level diagram''' check-box at the top-right corner.

Click on the check box.

It shows the energy of the electron.
|-
|| Cursor on the interface.
|| If this model were true,

it should take an electron only a fraction of a second to spiral into the nucleus.
|-
|| Click on the red button of light gun.
|| Turn on the light beam.
|-
|| Drag the speed slider to '''slow'''.
|| Drag the speed slider to '''slow'''.
|-
|| Click on '''Pause''' button>>> click '''Step''' button.
|| Click on '''Step''' button to view the energy of the electron.

Energy of the electron goes from highest to lowest in a fraction of a second.
|-
|| Cursor on the interface.

Click on the red button of light gun.
|| We know that this does not happen.

Atom is known to be stable.

Turn off the light beam.
|-
|| '''Slide Number 14'''

'''Limitations of Solar System model'''
|| Limitations of '''Solar System model'''

'''Rutherford''' model cannot explain,

The stability of an atom and also,

distribution of electrons and their energies.
|-
|| Cursor on the interface.

Click on '''Bohr''' model.

Cursor on the interface.
|| Back to the '''simulation'''.

From the '''Atomic Model''' list, click on '''Bohr'''.

'''Neils Bohr''' proposed a model of hydrogen atom to improve upon '''Rutherford's''' model.
|-
|| Point to electron and orbits in the zoom in box.

Point to orbits in the zoom in box.

Point to '''n=1,2,3,4''' in the '''Electron energy level''' diagram.
|| According to this model, 

The electron moves around the nucleus in an orbit of fixed radius and energy.

The energy of an electron in the orbit does not change with time.

These orbits are called energy levels.

These orbits are represented by '''n = 1,2,3,4''' etc in the '''Electron energy level''' diagram.
|-
|| Click on the red button of light gun.

Click on '''Play''' button.
|| Turn on the light beam.

Click on '''Play''' button.
|-
|| Point to electron in the first orbit of atom.

Point electron at '''n =1''' in energy level diagram.

|| Initially there is an electron in the 1st orbit of an atom.

'''Electron energy level''' diagram shows electron at n =1<sup>st </sup>level.
|-
|| Point to '''Electron energy level''' diagram.

Point to '''Electron energy level''' diagram.

|| Observe the electronic transition in '''Electron energy level''' diagram. 

Electron absorbs photon and gets excited to higher level.

Energy is emitted when electron moves from higher level to lower level.
|-
|| Point to electron in 1<sup>st</sup> level.
|| This electron returns back to 1<sup>st</sup> level.
|-
|| Point to spectrometer.

Point to emitted photons in the spectrometer.
|| Observe the spectrometer.

Spectrometer shows emitted photons.
|-
|| Click on '''Monochromatic''' radiobutton.
|| Under '''Light controls''', click on '''Monochromatic''' radio button.
|-
|| Check '''Show absorption wavelengths''' checkbox.
|| Then check '''Show absorption wavelengths''' checkbox.
|-
|| Point to four vertical spectral lines.
|| You will see four vertical spectral lines.

These lines represent the wavelength of absorption. 
|-
|| Point to highlighted slider.

Point to '''94 nm''' wavelength in text box.
|| The slider is highlighted on the first line.

Wavelength, '''94 nm''' as shown in the text box.
|-
|| Point to '''Electron energy level''' diagram.
|| As the photon strikes the electron,

observe the electronic transition at '''94 nm''' in '''Electron energy level''' diagram.
|-
|| Point to electron at n= 6 level.

Point to electron at n=1 level.
|| The electron moves to n= 6<sup>th</sup> level.

After a while, it moves to lower level by emitting photon.
|-
|| Click on the red button of light gun.
|| Turn off the light beam.
|-
|| '''Slide Number 15'''

'''Assignment '''
|| As an assignment,

Select '''Bohr''' Atomic model.

Change the light beam to '''Monochromatic'''.

Observe the electronic transitions at 103 nm, 112 nm, and 122 nm absorption wavelengths.
|-
||'''Slide Number 16'''

'''Assignment '''
||Observe the energy level diagram and the spectrometer results.

Note the observation and give an explanation.
|-
|| '''Slide Number 17'''

'''Limitations of Bohr’s model'''

The spectrum of atoms other than hydrogen.

Finer details of the hydrogen atom spectrum.

Ability of atoms to form molecules by chemical bonds.

||Limitations of '''Bohr’s''' model


|-
|| '''Slide Number 18'''

'''Limitations of Bohr’s model'''

Splitting of spectral lines in the presence of, 
a '''Magnetic field (Zeeman effect)''' 
or an '''Electric field (Stark effect)'''.

||'''Bohr's''' model was unable to explain the following phenomena.


|-
|| Cursor on the interface.

Point to '''deBroglie Model'''.
|| Back to the '''simulation'''.

Another model based on dual behaviour of electrons was proposed.
|-
|| Click on '''deBroglie model'''.

Point to wave in zoom in box.
|| Click on '''de Broglie''' from the '''Atomic Model''' list.

Notice the wave which represents electron in zoom-in box.
|-
|| '''Slide Number 19'''

'''deBroglie Atomic Model'''
|| 
'''deBroglie''' Atomic Model

The French physicist, '''de Broglie''' in 1924 proposed dual behavior of electrons.

Like radiation, matter should also exhibit both particle and wavelike properties.


|-
|| '''Slide Number 20'''

'''deBroglie Atomic Model'''

||Electrons should also have momentum as well as wavelength.

|-
|| Click on the red button of light gun.
|| Turn on the light beam.
|-
|| Point to electron>>Point to electron at higher energy level orbit.

Point to electron at lower energy level orbit.

Point to energy level diagram.
|| Notice that the electron absorbs photon and moves to higher energy level orbit.

Electron at higher energy level emits energy.

It returns to the lower energy level orbit.

Observe the electronic transitions in '''energy level diagram'''.
|-
|| Point to '''radial view''' drop-down box.

Click on drop-down arrow.

Scroll to '''3D view'''>>click on '''3D view'''.
|| Top-left corner of the view box has '''radial view''' drop-down box.

Click on drop-down arrow.

Scroll to '''3D view''' and click on it.
|-
|| Point to wave nature of electron in '''3D view'''.

Click on the red button of light gun.
|| Now observe the wave nature of electron in '''3D view'''.

Turn off the light beam.
|-
|| Cursor on the interface.
|| In order to explain the spectrum of hydrogen atom,

theory of quantum mechanics came into existence. 
|-
|| '''Slide number 21'''

'''Schrödinger Model'''

|| '''Schrödinger''' Model

'''Erwin Schrödinger''' proposed the quantum mechanical model of the atom.

'''Schrödinger''' used mathematical equations to describe the probability of finding an electron.
|-
|| '''Slide Number 22'''

'''Quantum Numbers'''
|| '''Quantum''' Numbers

The three coordinates that come from '''Schrodinger's''' wave equations are '''quantum''' numbers,

'''Principal (n)''', '''Angular (l)''', and '''Magnetic (m)'''.

|-
|| '''Slide Number 23'''

'''Quantum Numbers'''

||'''Quantum''' numbers describe size, shape and orientation of the orbitals.

|-
|| Cursor on the interface.

Click on '''Schrödinger''' model.

Point to atom in the zoom in box.
|| Back to '''simulation'''. 

Click on '''Schrödinger''' from the list.

In the zoom in box, atom is shown with nucleus surrounded by electron cloud.
|-
|| Click on the '''White''' radio button.
|| Switch back to '''White''' light.
|-
|| Click on the red button of light gun.
|| Turn on the light beam.

|-
|| Point to electron in zoom in box.
|| Observe that electron absorbs photon and moves to different orbital.
|-
|| Point to shapes of orbitals.
|| Observe the shapes of orbitals as the electron moves.
|-
|| Point to '''Electron energy level''' diagram. 

Point to n, l, m in '''energy level''' diagram.
|| Notice the electronic transitions in '''Electron energy level''' diagram. 

In addition to value of '''n''', '''energy level''' diagram has values for '''l''' and '''m''' also.
|-
|| Point to '''n, l, m''' value at the bottom right corner of the view box.

Point to '''n, l, m''' value.
|| Note '''n''', ''' l''', '''m''' values at the bottom right corner of the view box.

Note the change in '''n''', '''l''', '''m''' values as the photons strike the electrons.
|-
|| Cursor on the interface.
|| All these models compare how the experimental results match with the prediction.
|-
|| '''Slide Number 24'''

'''Assignment'''
|| As an assignment,

For the '''Schrodinger's''' atomic model, select '''Monochromatic''' light beam.

Note '''n,l,m''' values for the electron at four absorption wavelengths.

Note the orbital shape and possible orientation for each wavelength.
|-
|| '''Slide Number 25'''

'''Summary'''
|| Let us summarize.

In this tutorial, we have demonstrated,

How to use '''Models of the Hydrogen Atom''', ''' PhET simulation'''.
|-
|| '''Slide Number 26'''

'''Summary'''
|| Using this '''simulation''' we have,

Visualized different models of the hydrogen atom.

Explained the experimental predictions of each model.

Discussed limitations of each model.
|-
|| '''Slide Number 27'''

'''Summary'''
|| Determined the orbital shape and orientation from '''n''', '''l''' and '''m''' values.

Explained the energy level diagram.
|-
|| '''Slide Number 28'''

'''About Spoken Tutorial project'''
|| The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.
|-
|| '''Slide Number 29'''

'''Spoken Tutorial workshops'''
|| The '''Spoken Tutorial Project''' team:

conducts workshops using spoken tutorials and gives certificates on passing online tests.

For more details, please write to us.
|-
|| '''Slide Number 30'''

'''Forum for specific questions:'''

Do you have questions in THIS '''Spoken Tutorial'''?

Please visit this site

Choose the minute and second where you have the question.

Explain your question briefly

Someone from our team will answer them.

|| Please post your timed queries in this forum.
|-
|| '''Slide Number 31'''

'''Acknowledgements'''

|| This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
|-
|| '''Slide Number 32'''

'''Acknowledgement'''
|| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.
|-
|| 
|| This is Meenal Ghoderao from IIT Bombay.

Thank you for joining.
|-
|}