Particles wave nature

The miderstanding of molecular motions is necessarily based on quaiitum mechanics, the theory of microscopic physical behaviour worked out in the first quarter of the 20th century. This is because molecules are microscopic systems in which it is impossible—or at least very dangerous —to ignore the dual wave-particle nature of matter first recognized in quaiitum theory by Einstein (in the case of classical waves) and de Broglie (in the case of classical particles). 

Quantum mechanics began with a daring hypothesis by Louis de Broglie (he was a student at the time) if light has a dualistic wave/particle nature, why not matter His reasoning led to the prediction that a particle of mass m and velocity V would exhibit wavelike properties with wavelength... 

De Broglies insight into the wave-particle nature of matter had a profound effect on scientists picture of the atom. The solution to the wave equation led to a new way of looking at the atom. The old certainties of a solid electron circling a nucleus were gone. No longer could one say the electron is here or there. An electron in an atom could be anywhere, although some locations are more likely than others. 

The creation of quantum mechanics in 1925 by Heisenberg and in 1926 by Schrodinger did provide a firm theoretical basis for the quantum nature of the hydrogen atom. Bohr s quantum condition was no longer ad hoc quantization became a natural consequence of the wave-particle nature of the electron and all other subatomic particles. But neither Heisenberg s nor Schro-dinger s quantum mechanics provided an adequate account of the details of the hydrogen spectrum. 

Light is said to have a dual wave-particle nature. What does this statement mean (5.3)... 

Line spectra for multi-electron atoms are more complex than the hydrogen line spectrum, and thus are less easily explained in an explicit fashion at a middle school, high school, or even first year undergraduate level. However, discussions of this topic with respect to the hydrogen atom allow for the instructor to point out many important features of rudimentary quantum mechanics. Among these are the quantized nature of the electrons in atoms, the Bohr model of one-electron atoms, the dual wave-particle nature of light, the... 

What is the exact nature of light Does it consist of waves or is it a stream of particles of energy It seems to be both (see Figure 11.5). This situation is often referred to as the wave-particle nature of light. 

What is meant by the wave-particle nature of light ... 

The wave-particle nature of light refers to the fact that a beam of electromagnetic energy can be considered not only as a continuous wave, but also as a stream of discrete packets of energy moving through space. 

The solution, proposed by Einstein, was that the discrete energy units, identified by Planck, correspond to quanta of light, called photons, which interact with electrons in the metal surface during direct collision. This dual wave/particle nature of light inspired de Broglie to postulate a similar behaviour for electrons. Experimental observation of electron diffraction confirmed the wave nature of electrons and firmly estabUshed the dual character of all quantum objects as mysterious reality. As the logical pictme of an entity, which is wave as well as particle, is hard to swallow, it has become fashionable to avoid all physical models of quantum events it is considered poor taste to contaminate the quantmn world with classical concepts. This noble idea of the so-called Copenhagen interpretation of quantmn theory has resulted in a probabilistic computational model that, not only defies, but denies comprehension. 

Although Einstein s theory of light as a stream of photons rather than a wave explains the photoelectric effect and a great many other observations, it also poses a dilemma. Is light a wave, or does it consist of particles The only way to resolve this dilemma is to adopt what might seem to be a bizarre position We must consider that light possesses both wave-like and particle-like characteristics and, depending on the situation, will behave more like waves or more like particles. We will soon see that this dual wave-particle nature is also a characteristic trait of matter. 

This dual wave/particle nature is the basis of the quantum theory of electromagnetic radiation, which states that radiant energy can be absorbed or emitted only in discrete packets called quanta or photons. The energy E of each photon is given by... 

Although shown to have some serious flaws and long since abandoned, the Bohr model laid the groundwork for the more sophisticated theories of atomic structure that are accepted today and introduced the all-important concept that only specific energy states are allowed for an electron in an atom. Like electromagnetic radiation, electrons in atoms are now visualized as having a dual wave/particle nature. 

In 1905, Albert Einstein expanded on Planck s theory by introducing the radical idea that electromagnetic radiation has a dual wave-particle nature. Light exhibits many wavelike properties, but it can also be thought of as a stream of particles. Each particle carries a quantum of energy. 

The investigations into the photoelectric effect and hydrogen s emission line spectrum revealed that light could behave as both a wave and a particle. Could electrons have a dual wave-particle nature as well In 1924, the French scientist Louis de BrogUe asked himself this very question. And the answer that he proposed led to a revolution in our basic understanding of matter. 

The idea of electrons having a dual wave-particle nature troubled scientists. If electrons are both particles and waves, then where are they in the atom To answer this question, we must consider a proposal first made in 1927 by the German theoretical physicist Werner Heisenberg. 

In 1926, the Austrian physicist Erwin Schrodinger used the hypothesis that electrons have a dual wave-particle nature to develop an equation that treated electrons in atoms as waves. Unlike Bohr s theory, which assumed quantization as a fact, quantization of electron energies was a natural outcome of Schrodinger s equation. Only waves of specific energies, and therefore frequencies, provided solutions to the equation. Along with the uncertainty principle, the Schrodinger wave equation laid the foundation for modem quantum theory. Quantum theory describes mathematically the wave properties of electrons and other very small particles. 

The speed of electromagnetic radiation represents how fast energy is transferred through space, whereas the frequency of the radiation tells us how many waves pass a given point per time unit. 8. wave-particle nature (duality)... 

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