PhET-Simulations-for-Chemistry/C3/Rutherford-Scattering/English-timed

Time	Narration
00:01	Welcome to this tutorial on Rutherford Scattering simulation.
00:06	In this tutorial, we will demonstrate Rutherford Scattering, PhET simulation.
00:13	Here I am using- Ubuntu Linux OS version 14.04,
00:20	Java version 1.7.0,
00:25	Firefox Web Browser version 53.02.2
00:31	To follow this tutorial, learner should be familiar with topics in high school science.
00:39	Using this simulation, we will learn: about Plum pudding and Rutherford atomic models,
00:48	to visualize the Rutherford gold foil experiment,
00:52	about behavior of alpha particles,
00:56	to identify the factors that affect the deflection of alpha particles.
01:02	Now let us start the demonstration.
01:06	Use the given link to download the simulation.
01:11	I have already downloaded Rutherford Scattering simulation to my Downloads folder.
01:18	To open the simulation, right click on Rutherford Scattering html file.
01:26	Select Open with Firefox Web Browser option.
01:30	File opens in the browser.
01:33	This is the interface of Rutherford Scattering simulation.
01:38	The interface has 2 screens- Rutherford Atom, Plum Pudding Atom.
01:45	Let's begin with Plum Pudding Atom screen.
01:49	J. J. Thomson proposed Plum Pudding atomic model.
01:53	This model was proposed before Rutherford's atomic model.
01:58	Click on Plum Pudding Atom screen to open it.
02:02	Left side of the screen has experimental set up for Plum Pudding atomic model.
02:09	It consists of thin sheet of a metal above the Alpha Particles source.
02:15	Center of the screen has view box.
02:19	It shows a single atom with 3 into 10 to the power of -10 meter atomic scale.
02:26	In the atom, red portion represents the positive charge which is uniformly distributed.
02:33	Small blue spheres represent electrons which are embedded in the atom.
02:39	There is no separation between positive charge and electrons in the atom.
02:44	Screen on the right side shows 2 boxes, Legend and Alpha particle.
02:53	Legend box helps to identify the key components of the atom.
02:58	Alpha Particle box consists of- an Energy slider to change the energy of incoming alpha particles,
03:06	Traces check-box to show an alpha particle's trajectory.
03:11	Check the Traces check-box.
03:14	Bottom of the screen we have, Play/Pause button,
03:19	Step button and Reset button.
03:23	To turn on the Alpha Particles source, click on the blue button.
03:28	Notice that alpha particles beam strikes the thin metal foil.
03:33	Observe the path of alpha particles inside the atom.
03:37	All the alpha particles pass through the atom un-deflected.
03:42	This is because electrons are distributed evenly throughout the atom.
03:47	The magnitude of negative and positive charges inside the atom is equal.
03:53	This gives the most stable electrostatic arrangement.
03:57	Therefore it makes an atom electrically neutral.
04:01	Plum Pudding model was able to explain overall neutrality of the atom.
04:07	Plum Pudding model of an atom failed to explain: the stability of an atom,
04:15	position of the nucleus in an atom.
04:19	Plum Pudding model could not account for the atomic structure.
04:24	But it provided the base for the development of other atomic structure models.
04:31	Let's move on to Rutherford Atom screen.
04:35	Click on Rutherford Atom screen to open it.
04:39	Rutherford Atom screen helps to visualise the rutherford's gold foil experiment.
04:45	Rutherford Atom screen has same tools as that of Plum Pudding atom screen.
04:51	Additionally, there is an Atom box below Alpha Particle box.
04:56	Atom box consists of Protons and Neutrons sliders to change the composition of the nucleus.
05:04	Here, number of protons and neutrons is equal to that of gold atom.
05:09	At the centre of the screen, you will see a box.
05:13	It represents a zoom in view of different atoms in the gold foil.
05:19	Left side of the screen has 2 model views.
05:23	They are atomic view and nuclear view.
05:27	By default, atomic view is selected.
05:31	Atomic view gives an idea about the behavior of alpha particles as they travel through the atom.
05:38	Click on blue button to turn on the Alpha particles source.
05:43	Notice that alpha particles beam strikes the thin gold foil.
05:48	Check the Traces check-box to see the trajectories of alpha particles.
05:54	Observe the traces of alpha particles as they approach the nuclei of the atoms.
06:00	Now, pause the simulation and click on Step button.
06:06	Here, Most alpha particles are undeflected.
06:11	Some of the alpha particles are slightly deflected.
06:15	A very few alpha particles bounce back, that is, deflected by nearly 180°.
06:22	Let's see the behaviour of alpha particles in nuclear view.
06:27	Click on nuclear view.
06:29	Notice that in zoom in view, atoms are replaced by a single nucleus.
06:35	Now play the simulation.
06:38	Observe the deflections of alpha particles as they approach the nucleus.
06:44	Here n/p ratio for the gold atom is 1.5. Therefore alpha particles show a large deflection.
06:53	Let's study the factors that affect the scattering of alpha particles.
06:59	Drag the Energy slider towards minimum.
07:03	Observe that angles of deflection increases with the decrease in energy.
07:09	Next we will see, how change in composition of nucleus affects scattering of alpha particles.
07:16	Let's start with small nucleus with few number of protons and neutrons.
07:22	Drag the Energy slider back to its default position.
07:27	Then drag the Protons and Neutrons sliders towards 20.
07:32	Size of the nucleus becomes small.
07:35	Observe the angles of deflection of alpha particles.
07:39	Angle of deflection decreases with the decrease in protons and neutrons number.
07:45	Here atom is stable as n /p ratio is 1.
07:50	Observe that alpha particles far from the nucleus have almost no detectable deflection.
07:57	While the alpha particles that are close to the nucleus are deflected.
08:02	As an assignment, try various combinations of protons and neutrons and check the deflections.
08:10	Give an explanation for the change in the behaviour of the alpha particles.
08:16	Let us summarise.
08:19	In this tutorial, we have demonstrated how to use Rutherford Scattering, PhET simulation.
08:28	Using this simulation, we have learnt: about Plum pudding and Rutherford atomic models,
08:37	to visualize the Rutherford gold foil experiment,
08:41	about behavior of alpha particles,
08:45	to identify the factors that affect the deflection of alpha particles.
08:51	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
09:00	The Spoken Tutorial Project team conducts workshops using spoken tutorials and gives certificates on passing online tests.
09:09	For more details, please write to us.
09:13	Please post your timed queries on this forum.
09:17	This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
09:25	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
09:38	This is Meenal Ghoderao from IIT Bombay. Thank you for joining.

Contributors and Content Editors

Nancyvarkey