Tag: Particle physics
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Basic Properties of Nuclei
All nuclei are made up of two types of particles, namely: protons and neutrons. The only exception is the ordinary hydrogen nucleus, which is a single proton. Atomic Number, Neutron Number, Mass Number and Isotopes The following quantities are used to describe the atomic nucleus: The symbol used to show how many protons and neutrons…
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Spin Quantum Number
This property of atomic electrons was discovered through experimentation. The close observation of spectral lines revealed that each line was actually a pair of very closely-spaced lines, and what is referred to as fine structure was hypothesized to result from each electron “spinning” on an axis as if a planet. Electrons with different “spins” would…
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Bohr’s Correspondence Principle
Bohr’s correspondence principle states that predictions of quantum theory must correspond to the predictions of classical physics in the region of sizes where classical theory is known to hold. The classical sizes for length, mass, and time are on the order of centimeters, grams, and seconds and typically involve very large quantum numbers like can…
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Magnetic Quantum Number
The magnetic quantum number for an electron classifies which orientation its subshell shape is pointed. The “lobes” for subshells point in multiple directions. These different orientations are called orbitals. For the first subshell (s; l=0), which look like a sphere pointing in no “direction”, so there is only one orbital. For the second (p; l=1)…
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The Exclusion Principle
The exclusion principle states that no two electrons in an atom can have the same set of quantum numbers i.e. be in the same quantum state. Note, if this principle wasn’t valid, every electron would occupy the 1st atomic state (state of lowest energy), the chemical behaviour of the electrons would be significantly different and…
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Angular Momentum Quantum Number
A shell is made up of subshells. Subshells are regions of space where electron “clouds” are allowed to exist, and different subshells actually have different shapes. The first subshell is shaped like a sphere as illustrated in Fig 1.0(s) i.e. you can visualize it as a cloud of electrons surrounding the atomic nucleus in three…
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Principal Quantum Number
Symbolized by the letter n, this number describes the shell that an electron resides in. An electron “shell” is a region of space around an atom’s nucleus that electrons are allowed to exist, corresponding to the stable “standing wave” patterns of de Broglie and Bohr. Electrons may “leap” from shell to shell, but cannot exist…
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Yukawa Meson Theory of Nuclear Forces
In 1935 Yukawa proposed in his paper that there exist a meson field, that is, a field that is different from the electromagnetic field, whose quanta, the mesons have a finite mass, which is coupled to protons and neutrons in a manner analogous to the coupling of photons to charged particles. The exchange of these…