Modern View of the Atom

The law of conservation of matter states that matter is neither lost nor 

A 64 g sample of pure SOg was found to be composed of 32 g of sulfur combined with 32 g of oxygen. What is the percentage of sulfur in SO2  

Hydrogen peroxide, H2O2, is always 94.12% O. What is the percentage of H in hydrogen peroxide  

According to Dalton s atomic theory, a compound has a definite per- 

If the law of definite proportion is true, will the percent mass of silver, Ag, in silver sulfide be the same for aU lumps or pieces of Ag2S Explain your answer. 

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In 1907, Rutherford moved from Canada to Manchester University in England, and there he performed the experiments that gave us the modern view of the atom. In 1919, he moved back to Cambridge and assumed the position formerly held by J.J. Thomson. Not only was Rutherford responsible for very important work in physics and chemistry, but he also guided the work of no fewer than ten future recipients of the Nobel Prize. 

Once the modern conception of the atom, as outlined above, had been accepted, it became clear that the earlier views as to the mechanism of valency required x-evision. 

Atom The smallest portion of an element that can enter into chemical change, and cannot be further subdivided without destroying its identity. The modern view of an atom is of a positively charged nucleus (made up of electrically neutral neutrons and positive protons) surrounded by a cloud of negatively charged electrons. 

This illustration shows the modern view of an atom. Notice that a fuzzy, cloud-like region surrounds the atomic nucleus. Electrons move rapidly throughout this region, which represents most of the atom s volume. 

This picture—the modern picture of the atom—is hard to accept. Electrons can act as wave or particle, and their positions in an atom are governed by probabilities. The quantum mechanical view of the atom seems weird—because it is weird. But quantum mechanics beautifully explains the behavior of atoms. For example, chemists can now use quantum mechanics to predict the nature of the chemical bond that forms when atoms combine. 

The modern view of the periodic table explains its structure in terms of an Aufbau procedure based on the wave-mechanical model of the hydrogen atom. Although seductive at first glance, the model is totally inadequate to account for details of the observed electronic configurations of atoms, and makes no distinction between isotopes of the same element. The attractive part of the wave-mechanical model is that it predicts a periodic sequence of electronic configurations readily specified as a function of atomic number. The periodicity follows from the progressive increase of four quantum numbers n, l, mi and s, such that... 

How did Bohr s view of energy levels differ from the way energy levels are depicted in the modern model of the atom ... 

The key word in modern theory is evolution . The impressive consistency of the astro-nuclear view of the heavens has established the idea of an evolution of nuclear species which has the same significance for astrophysics as the evolution of living species for biology, it is itself preceded by an evolution of particle or corpuscular species, which would have been very short, lasting iess than i second. This process was of a quite crucial nature in determining the components available to buM up atoms, that is, those stable particles, protons and neutrons, that serve as the buMing-blocks, and the forces that bind them together. 

The modern view of HX addition is that H+ is transferred from HX to the alkene to give a carbocation. The major product is the one derived from the more stable carbocation. Compare the energies of 1-propyl and 2-propyl cations (protonated propene), 2-methyl-1-propyl and 2-methyl-2-propyl cations (protonated 2-methylpropene), and 2-methyl-2-butyl and 3-methyl-2-butyl cations (protonated 2-methyl-2-butene). Identify the more stable cation in each pair. Is the product derived from this cation the same product predicted by Markovnikov s rule Is the more stable carbocation also the one for which the positive charge is more delocalized Compare atomic charges and electrostatic potential maps for one or more pairs of carbocations. 

The Rutherford Experiment movie (eChapter 2.4) shows alpha particles impinging on a thin gold foil. Describe what happens to the alpha particles and discuss how the results of this experiment shaped the modern view of atomic structure. 

Inumph of abstract reasoning. The determination of the structures of molecules and extended structures is fundamental to the understanding of inorganic chemistry. It IS not possible to think of modern inorganic chemistry I n terms of simple equations such as Eq. 1.1 to IJ A three-dimensional view of the arrangement of atoms is... 

Explain the Impact of de Broglie s wave-particle duality and the Heisenberg uncertainty principle on the modern view of electrons in atoms. 

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