Chemistry

1. How does the electron cross the node in the p cloud
    Observing electrons on a quantum scale can lead to seemingly nonsensical answers. Up is down and left is right when dealing with quantum mechanics, and the valid, correct answer defies common sense. Consider how the electron can pass through the node in a p-orbital to jump from one lobe to another without the input of energy. Accordingly, the node is off-limits to the electron, as the node is the place where the probability of finding an electron is zero, basing on its wave function. In the case of a p-orbital electron, the node is located at the nucleus, thus the electron couldnt possibly be found at the node, and so couldnt pass nodes when it transfers to the opposite lobe.

    Another principle of quantum mechanics that bears significance in this dilemma is the so-called Heisenberg uncertainty principle, which states  It is impossible to specify simultaneously, with arbitrary precision, both the momentum and the position of a particle.  The angular momentum of an electron at the 2p orbital is pretty much given by the equation Ln(h2) by Bohr, but according to the uncertainty principle the distance r of the electron from the nucleus cannot be known or even approximated. The electron can be located anywhere along the second energy level at any point in time. We should also bear in mind that the surface of the p orbital is only an approximation of where the electron can be found more than 90 of the time, so 10 of the time it can be located outside this surface. Therefore the electron does not need to pass through the node to transfer from one lobe to another.

2. Discuss your wave-ness (your wave nature vs. your particle nature).
    Another postulate that goes against common sense but is time and time again invoked to explain various phenomena is the wave-particle duality. One particular phenomena that supports the validity of this theory is the diffraction of electrons, such as in electron microscopes. We know that electrons are particles, and yet its ability to go around corners like waves on water, even when interference by other electrons is eliminated by firing one electron at a time, encountering a block implies that it must have a wave-like quality. This theory is put in mathematical form by de Broglies relationship,   hm. This relationship applies to all objects with a mass m and moving at a speed , regardless of how massive the object is or how fast or slow it is moving. For instance, an electron (mass 9.11  10-31 kg) moving at 6  106 m s-1 by an electric potential of 100 V will have a wavelength of about 120 pm, which makes it suitable for electron diffraction techniques.

    Ordinary objects, because of the inverse relation of wavelength to mass, should have much smaller wavelengths according to the de Broglie relation. A 1 kilogram box moving at 1  m s-1 will then have a wavelength of 6.63  10-34 m, which corresponds to a very high energy wave. However, as classical physics hold more sway over ordinary objects than quantum mechanical effects such as the wave-particle theory the wave property of ordinary objects is mostly overridden, although any particle should still exhibit wave properties. Thus your every movement still  generates  quantum mechanical waves, although these waves are negligible in a macroscopic scale.

3. Discuss The act of observation changes the observed.
    Looking back at the Heisenberg uncertainty principle, the observer effect can be used to get some grasp of this difficult topic. The observer effect, wherein the act of observing changes the state of the quantity being observed, occurs quite often. One good example of an observer effect is the measurement of the temperature of a sample using a thermometer. As the thermometer does not actually measure the temperature of the sample but rather its own temperature (equal to the temperature of the sample when some time is allowed to pass), the measured temperature of the sample is not its actual temperature but rather the mean of its temperature and that of the thermometer, which may be hotter or colder than the sample. When Heisenberg first introduced his principle in his thesis, he envisioned a sort of microscope with which the electron can be directly observed. In this microscope, a beam of gamma rays is sent through an atom so that it hits an electron in the atom and rebound. This  observation , according to his thought experiment, of the electron changes its trajectory and motion, so that at the moment the position of the electron is measured its momentum changes. Like the thermometer and the temperature of the sample being measured, the act of measurement using the light from the  microscope  changes the state of the observed, so that the actual information  sought about the electron is lost. He designed this thought experiment in order to explain his proposal to his classically inclined colleagues, who still didnt understand his postulate and its implications. However this view of the uncertainty principle is somewhat questionable, as several loopholes (things like depth of field) can be found regarding the  experiment  that undermines its point. Nonetheless this thought experiment is useful in understanding the uncertainty principle at a basic level.