Rutherford’s experiment

C02-0042. Describe the scattering pattern that would have been observed in Rutherford s experiment if atoms were like chocolate chip cookies. 

The volume of an atom is determined by the size of its electron cloud. Example demonstrates that atomic dimensions are a little over 10 m, whereas Rutherford s experiments showed that nuclear dimensions are only about 10 m. This is 100,000 times smaller than atomic dimensions, so the nucleus is buried deep within the electron cloud. If an atom were the size of a sports stadium, its nucleus would be the size of a pea. Figure 7 1 shows a schematic view of two atoms with their electron clouds in contact with each other. 

Rutherford s experiment on alpha particle bombardment of gold foil... 

Figure 1.3 (a) Schematic of Rutherford s experiment to characterize the atom. 

The diagram above shows the results of Rutherford s experiment in which he used a radioactive source to shoot alpha particles at a thin sheet of gold foil. Based on these results, what were Rutherford s conclusions ... 

The third experiment that is crucial to understanding atomic structure was carried out by Ernest Rutherford in 1911 and is known as Rutherford s experiment. It consists of bombarding a thin metal foil with alpha (a) particles. Thin foils of metals, especially gold, can be made so thin that the thickness of the foil represents only a few atomic diameters. The experiment is shown diagrammatically in Figure 1.2. 

Rutherford s experiment demonstrated that the total positive charge in an atom is localized in a very small region of space (the nucleus). The majority of a particles simply passed through the gold foil, indicating that they did not come near a nucleus. In other words, most of the atom is empty space. The diffuse cloud of electrons (which has a size on the order of 10 8cm) did not exert enough force on the a particles to deflect them. The plum pudding model simply did not explain the observations from the experiment with a particles. 

Following Rutherford s experiments in 1911, Niels Bohr proposed in 1913 a dynamic model of the hydrogen atom that was based on certain assumptions. The first of these assumptions was that there were certain "allowed" orbits in which the electron could move without radiating electromagnetic energy. Further, these were orbits in which the angular momentum of the electron (which for a rotating object is expressed as mvr) is a multiple of h/2ir (which is also written as fi),... 

Rutherford s model of the atom was an analogy to the sun and the planets. A small positively charged nucleus is surrounded by circling electrons and mostly by empty space. Rutherford s experiment is explained in greater detail in this flash animation ... 

The structure of the atom and the organization of the periodic table are so inextricably intertwined as to be inseparable. We will examine the structure of the atom first and then see how this structure determines the arrangement and function of the periodic table. The twentieth century was the setting for the unraveling of many secrets of the atom, with the remainder of its secrets on the scientific horizon. At the beginning of the century, the atom was viewed as a small, solid unit. Early in that century, Ernest Rutherford s experiments showed it to be mostly empty space—a truly startling idea said to be the shot heard round the scientific world. His work led to the conclusion that the atom has a dense, positive center, called the nucleus that is quite small compared to the entire atom. An analogy can be drawn about this size comparison If the whole atom were the size of Yankee Stadium, the nucleus would be the size of the baseball held by the pitcher. 

Also in the early 1900s Ernest Rutherford performed his famous Gold Foil Experiment. Rutherford set up an experiment in which a radioactive substance released alpha particles. These particles were aimed at a thin sheet of gold foil. A screen coated with zinc sulfide was set up around the gold foil to detect the alpha particles when they hit the screen. Rutherford s experiment... 

The number 12, shown as a superscript, is called the mass number for the element. The mass number is the sum of the protons and neutrons in the nucleus of the atom. Recall from Rutherford s experiment that the nucleus contains the atom s mass. Because protons and neutrons are the particles in the nucleus of the atom, they make up the mass of the atom because the masses of the electrons are minimal in comparison. The number 6, shown as a subscript, is called the atomic number. This can be defined as the number of protons in the nucleus, the nuclear charge (protons are the only nucleons with a charge), or the number of electrons in a neutral atom. How many neutrons are in carbon-12 To find the number of neutrons in the atom, subtract the atomic number from the mass number. In this case there are 6 neutrons in this atom. 

Rutherford s experiment on a-partide bombardment of metal foil. (Gold foil was used in the original experiments because it can be hammered into extremely thin sheets.)... 

Refer to the "Atoms and Moles" chapter for a discussion of Rutherford s experiment... 

We do not know whether seemingly objective scientific witnesses ever saw a real transmutation in an alchemists laboratory, but we do know that transmutation is possible. It goes on naturally all the time as radioactive elements decay and give off" radiation—and the end-product of this "putrefaction" is lead. Transmutation is also possible in a modem laboratory. Apart from the changes from one known element to another, as in Rutherford s experiment, there are more than a dozen new elements known to science which do not occur naturally at all, but which have been made in the course of experiments in nuclear energy. The only limitation to laboratory transmutation at the moment is that subatomic particles that travel at high speeds and with immense energies are needed. 

In the first place, Rutherford s experiments show definitely (1913)... 

Figure 2.6 (on the next page) is a three-part representation of Rutherford s experiment. Tiny, dense, positively charged alpha (a) particles emitted from radium were aimed, like minute projectiles, at thin gold foil. The figure illustrates... 

Animation Rutherford s Experiment Online Learning Center... 

Rutherford s experiment on a particle bombardment of metal foil... 

How does Rutherford s experiment support the existence of a positively charged, dense nucleus ... 

Recall Rutherford s experiment from Chapter 3. What was the experiment and what did it show ... 

Remember that in Chapter 3 we discussed the idea that an atom has a small positive core (called the nucleus) with negatively charged electrons moving around the nucleus in some way (see Figure 11.1). This concept of a nuclear atom resulted from Ernest Rutherford s experiments in which he bombarded metal foil with a particles. 

Rutherford s experiment In the experiment, a narrow beam of alpha particles was aimed at a thin sheet of gold foil. A zinc-sulfide-coated screen surrounding the gold foil produced a flash of light when struck by an alpha particle. By noting where the flashes occurred, the scientists could determine if the atoms in the gold foil deflected the alpha particles. 

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