Rutherford-Bohr model

In the early part of the twentieth century, then, a simple model of atomic structure became accepted, now known as the Rutherford nuclear model of the atom, or, subsequently, the Bohr-Rutherford model. This supposed that most of the mass of the atom is concentrated in the nucleus, which consists of protons (positively charged particles) and neutrons (electrically neutral particles, of approximately the same mass). The number of protons in the nucleus is called the atomic number, which essentially defines the nature of... 

For nearly half a century, Mendeleev s periodic table remained an empirical compilation of the relationship of the elements. Only after the first atomic model was developed by the physicists of the early twentieth century, which took form in Bohr s model, was it possible to reconcile the involved general concepts with the specificity of the chemical elements. Bohr indeed expanded Rutherford s model of the atom, which tried to connect the chemical specificity of the elements grouped in Mendeleev s table with the behavior of electrons spinning around the nucleus. Bohr hit upon the idea that Mendeleev s periodicity could... 

Scientists of the nineteenth century lacked the concepts necessary to explain line spectra. Even in the first decade of the twentieth century, a suitable explanation proved elusive. This changed in 1913 when Niels Bohr, a Danish physicist and student of Rutherford, proposed a new model for the hydrogen atom. This model retained some of the features of Rutherford s model. More importantly, it was able to explain the line spectrum for hydrogen because it incorporated several new ideas about energy. As you can see in Figure 3.8, Bohr s atomic model pictures electrons in orbit around a central nucleus. Unlike Rutherford s model, however, in which electrons may move anywhere within the volume of space around the nucleus, Bohr s model imposes certain restrictions. 

Explain how the Bohr atomic model differs from the Rutherford atomic model, and explain the observations and inferences that led Bohr to propose his model. 

Both the Rutherford and Bohr atomic models have been described as planetary models. In what ways is this comparison appropriate In what ways is this comparison misleading ... 

The Bohr model of the atom took shape in 1913. Niels Bohr (1885-1962), a Danish physicist, started with the classic Rutherford model and applied a new theory of quantum mechanics to develop a new model that is still in use, but with many enhancements. His assumptions are based on several aspects of quantum theory. One assumption is that light is emitted in tiny bunches (packets) of energy call photons (quanta of light energy). 

The 3rd Solvay Conference in Physics took place in 1921, after a long interruption due to the First World War. Its theme was Atoms and Electrons. 20 It was centered on the Rutherford model of the atom and Niels Bohr s atomic theory. Bohr, however, was not able to attend the conference because of illness. 

Just as the Rutherford model of the atom developed in 1911 was scientifically startling with its revelation of the atom as mostly empty space, so was the Bohr model of the atom introduced in 1913 with its definition of the location of the electron within the atom. As Bohr and others realized that the atomic spectrum of each element is caused by electrons changing energy levels, a different picture of the atom emerged. The new picture of the atom had electrons at various energy levels within the empty space of Rutherford s model (Figure 8.6). This space can still be said to be empty because the mass of the electrons is extraordinarily small in comparison with that of the whole atom. 

The Rutherford model of the atom, in turn, was replaced only two years later by a model developed by Niels Bohr, a Danish physicist. The Bohr model, which is shown in Figure 16, describes electrons in terms of their energy levels. 

How does Bohr s model of the atom differ from Rutherford s ... 

Although there is no detector that allows us to see the inside of an atom, scientists infer its structure from the properties of its components. Rutherford s model shows electrons orbiting the nucleus like planets around the sun. In Bohr s model the electrons travel around the nucleus in specific energy levels. According to the current model, electron orbitals do not have sharp boundaries and the electrons are portrayed as a cloud. 

Recall that hydrogen s atomic emission spectrum is discontinuous that is, it is made up of only certain frequencies of light. Why are elements atomic emission spectra discontinuous rather than continuous Niels Bohr, a young Danish physicist working in Rutherford s laboratory in 1913, proposed a quantum model for the hydrogen atom that seemed to answer this question. Impressively, Bohr s model also correctly predicted the frequencies of the lines in hydrogen s atomic emission spectrum. 

In Rutherford s model the electron falls on the nucleus. In Bohr s model the electron does not fall on the nucleus. 

The "orbital" concept is not precisely defined and according to Coulson [4] is a relic from the Bohr-Rutherford planetary model of the atom ... 

TheoreticThomson model (a mix of peirticles with positive md negative charges), B— the Rutherford model (a positive nucleus surroimded by electrons), C—the Bohr model (stating that electrons follow defined orbits around a nucleus), [Pg.14]

Bohr first proposed an electron motion model to solve the problems of the Rutherford model. For the electron in a hydrogen atom, Bohr presented an atomistic model, in which the periodic orbits of electrons are quantized, and proposed the following hypothesis, known as the Bohr hypothesis (Bohr 1913) ... 

Rutherford had discovered that the volume of a nucleus was very small compared with the total volume of an atom. In fact, if the nucleus were the size of a marble, then the size of the atom would be about the size of a football field. But where were the electrons This question was not answered until Rutherford s student, Niels Bohr, proposed a model in which electrons surrounded the positively charged nucleus as the planets surround the sun. Bohr s model is discussed in a later chapter. 

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