Absolutely Small - Michael D. Fayer [145]
probability amplitude wave—Quantum mechanical wave (wavefunction) that describes the probability of finding a particle in some region of space. A probability amplitude wave can go positive and negative. The probability of finding a particle in some region of space is related to the square (actually the absolute value squared) of the probability amplitude wave. The greater the probability in some region of space, the more likely the particle will be found there.
proton—A subatomic particle that has a positive charge. It is one of the basic constituents of atoms and molecules. Its positive charge is the same size but opposite in sign from the negative charge of an electron. An atom has the same number of electrons and protons, so it has no overall charge. The number of protons in an atomic nucleus, called the atomic number, determines the charge of the nucleus. Different atoms have different numbers of protons in their nuclei.
quantized energy levels—Energy levels that come in discreet steps. The energy is not continuous. Atoms and molecules have quantized energy levels.
quantum number—A number that defines the state of a quantum mechanical system. There can be more than one quantum number to fully specify the state. In an atom, each electron has four quantum numbers, n, l, m, and s, which can only take on certain values. Quantum numbers arise from the mathematical description of quantum mechanical systems.
radial distribution function—The mathematical function that describes the probability of finding an electron a certain distance from the nucleus of an atom independent of the direction. It is obtained from the wavefunction for the electron in the atom.
Rydberg formula—The early empirical formula that gave the colors of light emitted or absorbed by hydrogen atoms.
Schrödinger Equation—A fundamental equation of quantum theory. Solution of the Schrödinger Equation for an atom or molecule gives the quantized energy levels and the wavefunctions that describe the probability amplitude of finding electrons in regions of space in an atom or molecule.
single bond—A chemical bond that holds two atoms together through the sharing of one pair of electrons.
size, absolute—An object is large or small depending on whether the intrinsic minimum disturbance that accompanies a measurement is negligible or nonnegligible. If the minimum disturbance is negligible, the object is large in an absolute sense. If it is nonnegligible, it is absolutely small. Absolutely small objects can be described by quantum mechanics, but not by classical mechanics.
size, relative—Size is determined by comparing one object to another. An object is big or small only in relation to another object. In classical mechanics it is assumed that size is relative. Classical mechanics cannot describe objects that are small in an absolute sense.
spatial probability distribution—The probability of finding a particle, such as an electron, in different regions of space. The spatial probability distribution can be calculated from the quantum mechanical wavefunction for a particle.
spectroscopy—The experimental measurement of the amount and colors of light that are absorbed or emitted by a system of atoms or molecules.
Superposition Principle—“Whenever a system is in one state, it can always be considered to be partly in each of two or more states.” This quantum mechanical principle says that a system in a particular quantum state can also be described by the superposition (addition) of two or more