141 原子的化学性质
Chemical Properties of Atoms
（https://www.nuclear-power.com/）
原子的化学性质
Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. The chemical properties of the atom are determined by the number of protons, in fact, by number and arrangement of electrons. The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.
每一种固体、液体、气体和等离子体都是由中性或电离原子组成的。原子的化学性质是由质子的数量决定的，事实上，是由电子的数量和排列决定的。这些电子的配置遵循量子力学的原理。每个元素的电子壳层，特别是最外层的价电子壳层中的电子数是决定其化学键行为的主要因素。在元素周期表中，元素是按照原子序数Z递增的顺序排列的。
The total number of protons in the nucleus of an atom is called the atomic number (or the proton number) of the atom and is given the symbol Z. The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19coulombs. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom.
原子核中的质子总数被称为原子的原子序数（或质子数），并用符号Z表示。电中性原子中的电子数与原子核中的质子数相同。因此原子核的总电荷是+Ze，其中e（基本电荷）等于1602 x 10^-19库仑。每个电子都受到原子核正电荷和原子中另一个（Z - 1）负电子所产生的电场的影响。
It is the Pauli exclusion principle that requires the electrons in an atom to occupy different energy levels instead of them all condensing in the ground state. The ordering of the electrons in the ground state of multielectron atoms, starts with the lowest energy state (ground state) and moves progressively from there up the energy scale until each of the atom’s electrons has been assigned a unique set of quantum numbers. This fact has key implications for the building up of the periodic table of elements.
这就是泡利不相容原理，它要求原子中的电子占据不同的能级，而不是它们都凝聚在基态。在多电子原子的基态中，电子的排列顺序从能量最低的状态（基态）开始，并从那里逐步向上移动，直到原子的每个电子都被分配了一组独特的量子数。这一事实对元素周期表的建立有着重要的意义。
（待续）