Oil-drop experiments

Microwave spectroscopy, 249 Millikan, Robert, 241 oil drop experiment, 241 Minerals, 373, 385 Miscible, 176 Model... 

OH molecules, reaction between, 282 Oil-drop experiment, 241 Oil of wintergreen, 346 Oleomargarine, 407 Open hearth furnace, 404 Operational definition, 195 Orbital representation of chemical bonding, 278 Orbitals atomic, 262, 263 dand/, 262... 

C02-0041. In Millikan s oil drop experiment, some droplets have negative charges, so others must have... 

If any oil droplets in Millikan s oil drop experiment had possessed a deficiency of electrons, the droplets would have been positively charged and would have been attracted to, not repelled by, the negatively charged plate. There would have been no voltage setting possible where the electrical and gravitational forces on the drop would have balanced. 

The first modern atomic theory was developed by John Dalton and first presented in 1808. Dalton used the term atom (first used by Democritus) to describe the tiny, indivisible particles of an element. Dalton also thought that atoms of an element are the same and atoms of different elements are different. In 1897, J. J. Thompson discovered the existence of the first subatomic particle, the electron, by using magnetic and electric fields. In 1909, Robert Millikan measured the charge on the electron in his oil drop experiment (electron charge = -1.6022 x 10-19 coulombs), and from that he calculated the mass of the electron. 

Extremely stringent lower limits were reported by Rank (29) in 1968. A spectroscopic detection of the Lyman a(2 p - 1 s) emission line of the quarkonium atom (u-quark plus electron) at 2733 A was expected to be able to show less than 3 108 positive quarks, to be compared with 1010 lithium atoms detected by 2 p - 2 s emission at 6708 A. With certain assumptions (the reader is referred to the original article), less than one quark was found per 1018 nucleons in sea water and 1017 nucleons in seaweed, plankton and oysters. Classical oil-drop experiments (with four kinds of oil light mineral, soya-bean, peanut and cod-liver) were interpreted as less than one quark per 1020 nucleons. Whereas a recent value (18) for deep ocean sediments was below 10 21 per nucleon, much more severe limits were reported (30) in 1966 for sea water (quark/nucleon ratio below 3 10-29) and air (below 5 10-27) with certain assumptions about concentration before entrance in the mass spectrometer. At the same time, the ratio was shown to be below 10 17 for a meteorite. Cook etal. (31) attempted to concentrate quarks by ion-exchange columns in aqueous solution, assuming a position of elution between Na+ and Li+. As discussed in the next section, cations with charge + 2/3 may be more similar to Cs+. Anyhow, values below 10 23 for the quark to nucleon ratio were found for several rocks (e.g., volcanic lava) and minerals. It is clear that if such values below a quark per gramme are accurate, we have a very hard time to find the object but it needs a considerably sophisticated technique to be certain that available quarks are not lost before detection. 

The classical electrostatic balance is the Millikan condenser, which was first used to measure the charge on the electron in the famous Millikan oil-drop experiment. In principle, the device can be used to levitate a small charged mass by using the electrical field generated by two flat plates to... 

Millikan determined the charge of an electron with this oil-drop experiment. 

Robert Millikan Mass of an electron His famous oil-drop experiment established the charge on an electron. 

The best proof of the validity of Stokes law (although indirect) was the Millikan oil drop experiment. Stokes law has been shown to give... 

Mass 1 atomic mass unit (AMU) 1 AMU 1/1836 AMU (discovered by Millikan in his oil drop experiment)... 

A chemist in a galaxy far, far away performed the Millikan oil drop experiment and got the following results for the charge on various drops. What is the charge of the electron in zirkombs ... 

Note that the electrical charge of an electron (Chap. 8) is —1.602 X 10 coulombs, as determined by the X-ray method, the Millikan oil-drop experiment, and other methods. Avogadro s number is 0.6023 X 10-. The product of these numbers is —96,500 coulombs of electricity. This is accordingly the electrical charge, the quantity of electricity, on Avogadro s number of electrons, 1 mole of electrons. It is customary to define the faraday as this quantity of positive electricity, rather than of negative electricity. 

In a reproduction of the Millikan oil-drop experiment, a student obtains the following values for the charges on nine different oil droplets. 

Once the charge-to-mass ratio for the electron had been determined, additional experiments were necessary to determine the value of either its mass or its charge, so that the other could be calculated. In 1909, Robert Millikan (1868-1953) solved this dilemma with the famous oil-drop experiment, in which he determined the charge of the electron. This experiment is described in Figure 5-2. All of the charges measured by Millikan turned... 

This is only about 1/1836 the mass of a hydrogen atom, the lightest of all atoms. Millikan s simple oil-drop experiment stands as one of the cleverest, yet most fundamental, of all classic scientific experiments. It was the first experiment to suggest that atoms contain integral numbers of electrons we now know this to be true. 

Another of Thomson s significant contributions was the determination of the charge-to-mass ratio of the electron. This bit of evidence aided physicist Robert Millikan, in 1909, to determine the mass of the electron in his famous oil-drop experiment. 

The Milliken oil-drop experiment amply demonstrates that multiply charged droplets can exist as stable entities. Accepting this fact, we pose the question, How small can the droplet be i.e., can an atom or molecule become multiply negatively charged In an attempt to address this... 

Figure 2.5 Millikan s oil-drop experiment for measuring an electron s charge. The motion of a given oil droplet depends on the variation in electric field and the total charge on the droplet, which depends in turn on the number of attached electrons. Mi Ilikan reasoned that the total charge must be some whole-number multiple of the charge of the electron.

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