You can gain access to the elf menu, for the quantum lab, by clicking on the bell in the stockroom. The general features of the inorganic simulation include 26 actions that cam be added to test tubes in any combinations, 11 reagents that can be added to the test tubes In any sequence and any number of times. The actions are located in the stockroom. You can gain access to the help menu, for the Inorganic lab, by clicking on the bell in the stockroom. Purpose You will learn to work in the Virtual Laboratory. Keep accurate records. Record your observation In the notes portion of the report.
Procedure Part 1: Once the program has loaded, enter the quantum lab. Enter the stockroom. Note the bell on the counter. Click on the bell to gain access to the help screens for this lab. Become aware of what the help screen has to offer. Exit the help screen. “Play-around” with the lab and learn the features available. Part 2: Exit quantum lab and enter Inorganic lab. Click on the TV handle in the top left side of the virtual lab. A screen will drop. This screen provide the current chemical status of what is contained in your selected test tube. Enter the stockroom.
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Note the bell on the counter. Click on the bell to gain access to the help screens for this lab. Become aware of what the help screen has to For this lab, record the most important concept that you learned in the Notes section: Notes: The lab allowed me to view what everything is and how to use them. The most important thing that I learned was how to use this lab. Knowing how to use this program will benefit me with the other lab that I need to work on. I didn’t think that I would understand how to use the lab and this help but I still don’t understand this completely. VS..) Assignment – Thomson Experiment As scientists began to examine atoms, their first discovery was that they could extract actively charged particles from atoms. They called these particles electrons. In order to understand the nature of these particles, they wanted to know how much they weighed, and how much charge they carried. Thompson showed that if you could measure how much a beam of electrons were bent in an electric and magnetic field, you could figure out the ratio of mass to charge for the particles. You will repeat some of Thomson experiments in this lab.
Procedure / Observations 2. Enter the Quantum Lab in VS… Set up the optics table for this experiment by selecting Thomson Experiment on he clipboard (in the stockroom). What source is used in this experiment Electron gun What type of charge do electrons have? Negative What detector is used in this experiment and what does it do? A Phosphor Screen Push the grid button on the phosphor screen, then turn on the magnetic field to 3. 30TH (micro-Taste, measurement of magnetism). What happens to the spot from the election gun? Which way did it shift) Moved to 4. Turn off the magnetic field, and turn on the voltage of the electric field to VIVO. What happens to the spot from the election gun? (which way did it shift) Moved to the left. In an electric field, the displacement of the electrons is related to their charge, mass, and velocity. The purpose of the Thomson experiment is to calculate the mass to charge ratio of the electron. The displacement of the electrons can be observed in this experiment, and the velocity can be calculated from the electric and magnetic fields.
The forces produced by the electric and magnetic fields are CEQ and q 0 Vs.. B, respectively (where q is the charge of the electron, V is its velocity, E is the electric field, and B is the magnetic field). If the electric and magnetic forces are equal, then he velocity of the electron can be calculated from E and B (V=E/B). What two fundamental properties of the electron does its displacement depend on? Mass and Velocity Where should the signal on the phosphor screen be if the electric and magnetic forces are balanced? In the dead center Increase the voltage of the electric field until the signal reaches the edge of the 5. Hockshop screen What voltage is required to deflect the electrons to the edge of the screen? 1 5. V Increase the magnetic field until the beam of electrons reaches the center of 6. The screen. What magnetic field creates a magnetic force that balances the electric force? 0. 0 When the electrical and magnetic forces are equal, what does the ratio of the electric field to magnetic field (E/B) give? 2. 48 x 105 Increase the electron gun energy to 500 eve 7. How does increasing the electron gun energy change the speed of the electrons?
It moves to the right 1. 5 CM What voltage is required to deflect the electrons to the edge of the screen? Move than 999 eve than seen in the earlier experiment? It required more voltage because of the starting point Discussion Thompson lab was successful in showing that the mass and velocity are directly elated and they show the correlation between the magnetic forces being equal. This lab showed us how to accurately calculate the electron displacement theory. To calculate this you use E & B with the formula V=E/B. In our lab we got 2. 48 x 105 .
Increasing our electron gun moved the electron speed to the right which showed the increasing electron speed. To increase the electrons completely to the edge of the screen which shows highest electron charge you’d need to increase it to 999. You need the increased voltage and eve because it needs all the positive charged electron and electricity to increase the speed and voltage. (VS..) Assignment – Milliken Experiment In the Thomson experiment, you discovered that you can use the deflection of an electron beam in electric and magnetic fields to measure the charge-to-mass ratio of an electron.
If you then want to know either the charge or the mass of an electron, you need to have a way of measuring one or the other independently. Milliken and his student Harvey Fletcher showed that they could make very small oil drops and deposit small numbers of electrons on these drops. (1 to 10 electrons). They would then measure the total charge on the oil drops. You will get chance to repeat their experiments. Set up the optics table for this experiment by selecting Milliken Oil Drop Experiment on the clipboard (in the stockroom).
Electron gun, oil mist and camera How does this source affect the oil droplets in the oil mist chamber? It doesn’t effect it What do you observe from the video camera screen? Do all the oil drops fall at the same speed? No some fall fast and some fall slow. What force causes the drops to fall? Gravity causing the drops to fall The oil drops fall at their terminal velocities. The terminal velocity depends on the radius of the drops. By measuring the velocity of a droplet, the radius can be calculated. Then the mass of the drop can be calculated from its radius and the density of the oil.
Why do the droplets fall at different velocities? Because of the radius of the droplets 3. Turn on the electric field to 400 V. What do you observe on the detector screen? That some of the oil droplets still fall and the other rise at a rapid speed What type of charge do the drops have? Negative charge The force exerted on an oil drop by the electric field depends on the amount of charge deposited on the drop, since the force on a charged particle is CEQ. Each drop has a certain number electrons attached to it, so the charge on each drop is an integral multiple of the charge of an electron.
By calculating the charge on several droplets, the charge of an electron can be determined. Besides the gravitational force, what other force affects the velocity of the charged oil drops. The voltage being increased began to exert more force upon the oil droplets which caused them to have an increased electron number attached increasing the droplets force exerting them up and down Will this force have more or less of an effect if the oil drop has more deposited electrons? Why? It will have more because it increases the electron charge causing them to go up and down.
We were able to successfully reenact Milliken and Harvey Fletcher ability to show the current between oil drops and the electron deposits on them. Upon misting of respond much at all. They were very slow and only fell down with gravity. There wasn’t enough to increase the electron charge within. Upon increasing of the veto 400 eve were able to see the positive charge that the oil drops obtained. This increasing the electron charge and causing the oil droplets to not only fall but also ounce back up due to their positive charges within. VS..) Assignment – Rutherford Backscattering Experiment A key experiment in understanding the nature of atomic structure was completed by Ernest Rutherford in 1911. He set up an experiment that directed a beam of alpha particles (helium nuclei) through a gold foil and then onto a detector screen. According to the “plum pudding” atomic model, electrons gloat around in a cloud of positive charge. Based on this model, Rutherford expected that almost all the alpha particles should not be deflected, but he expected a few to be slightly fleeted by electrons.
However, he observed that alpha particles emerged at all angles, even straight backwards. He described the as “. … Almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. ” He suggested that the experiment could be understood if almost all of the mass of an atom was concentrated in a small, positively charged central nucleus. In this experiment, you will make observations similar to those of Professor Rutherford. Set up this experiment by selecting Rutherford Backscattering on the clipboard (in the stockroom). Phosphor screen What are alpha particles?
Helium nuclei, which each have two protons, and two neutrons with a charge of +2 What detector is used in this experiment and what does it do? Phosphor screen detects charged particles like electrons and it glows momentarily at the positions where the particles impact the screen What is the signal in the middle of the screen? The alpha particles coming straight through the gold foil UN deflected or only slightly deflected What do the other signals on the screen mean? There are other momentarily spots of light these represent hits from alpha particles being deflected at small angles
Are most of the alpha particles undetected or deflected? Undetected According to the “plum pudding” model, what causes the slight deflection of some of the alpha particles? As the positively charged alpha particles pass through the gold atom, they are attracted to negative electrons and their path is slightly bent. 3. Now move the phosphor screen to the front left of the optics table in order to detect backwards scattering. What causes alpha particles to deflect backwards? A large mass in the center of the atom. How do the results of this experiment contradict the “plum pudding” atomic model?
The mass of the gold atom is not spread over the full atomic volume but concentrated in a central atomic nucleus. Are the atoms of the fold foil composed mostly of matter or empty space Empty space How does this experiment show that almost all the mass of an atom is concentrated in a small, positively charged central nucleus? Most of the alpha particles came straight through with little or no deflections, but there was the occasional large deflection. Electrons, the path being slightly bent Why did Rutherford conclude that almost all the mass of an atom must be concentrated in a small, positively charged central nucleus?
Most of the alpha particles came straight through with little or no deflections, but there was the occasional large deflection. If the mass of an atom were not concentrated, the number of deflections would be smaller and there would be no appearance of large deflections. The lab was to prove that particles are UN deflected and controlled by electrons. We were able to show how particles move, and we were able to describe them and incur that with the gold foil it actually deflected the atoms, causing their shapes to be seen. This proves that the atoms must be positively charged electrons