何謂電子密度(electron density) ?
Thanks 麻煩一下XD .
- 天戒Lv 69 年前最佳解答
在電磁學裏，電荷密度是一種度量，描述電荷分佈的密度。電荷密度又可以分類為線電荷密度、面電荷密度、體電荷密度。假設電荷分佈於一條曲線或一根直棒子，則其線電荷密度是每單位長度的電荷密度，單位為庫侖／公尺 (coulomb/meter) 。假設電荷分佈於一個平面或一個物體的表面，則其面電荷密度是每單位面積的電荷密度，單位為庫侖／公尺2 (coulomb/meter2) 。假設電荷分佈於一個三維空間的某區域或物體內部，則其體電荷密度是每單位體積的電荷密度，單位為庫侖／公尺3 (coulomb/meter3) 。由於在大自然裏，有兩種電荷，正電荷和負電荷，所以，電荷密度可能會是負值。電荷密度也可能會相依於位置。特別注意，不要將電荷密度與電荷載子密度(charge carrier density) 搞混了。電荷密度與電荷載子的體積有關。例如，由於鋰陽離子的半徑比較小，它的體電荷密度大於鈉陽離子的體電荷密度。
- 9 年前
Electron density is the measure of the probability of an electron being present at a specific location.
In molecules, regions of electron density are usually found around the atom, and its bonds. In de-localized or conjugated systems, such as phenol, benzene and compounds such as hemoglobin and chlorophyll, the electron density covers an entire region, i.e., in benzene they are found above and below the planar ring. This is sometimes shown diagrammatically as a series of alternating single and double bonds. In the case of phenol and benzene, a circle inside a hexagon shows the de-localized nature of the compound.
What is electron density? The theory of quantum mechanics says that an electron's position can only be described statistically. It also describes a method for calculating the probability of finding an electron at one point or another. This calculation produce a quantity called electron density, a number that tells us the relative probability of finding an electron at a particular point in space.Quantum mechanics also says that an electron can be viewed as a stationary wave, or, cloud of negative charge. According to this point of view, the electron density is a number that tells us how much charge is located at each point in the cloud.The following sections describe these ideas in more detail, beginning with the mathematical connection between wave functions (orbitals) and electron density.