01 元素和元素周期表
The number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, Z. The number of electrons in an electrically neutral atom is also equal to the atomic number, Z. The total mass of an atom is determined very nearly by the total number of protons and neutrons in its nucleus. This total is called the mass number, A. The number of neutrons in an atom, the neutron number, is given by the quantity A-Z.
原子核内的质子数被称为原子序数,或质子数，Z。一个电中性原子的电子数量也等于原子序数，Z。原子的总质量接近核内质子数和中子数之和。这个总数被称为质量数A。中子在一个原子中的数量,中子数,给出了的数量为A-Z。
The term element refers to, a pure substance with atoms all of a single kind. To the chemist the "kind" of atom is specified by its atomic number, since this is the property that determines its chemical behavior. At present all the atoms from Z = 1 to Z = 107 are known; there are 107 chemical elements. Each chemical element has been given a
name and a distinctive symbol. For most elements the symbol is simply the abbreviated form of the English name consisting of one or two letters, for example:
单质是指,一个纯物质由一种原子组成的。化学家认为这种原子由它的原子数决定,因为它的性质决定了其化学行为。目前所有被知道的原子是Z = 1 到Z = 107的的原子，有107种化学元素。每一种化学元素被给以一个名字和一个独特的符号。对于大多数元素符号都仅仅是英文名称缩写为一个或两个字母,例如:
oxygen==O nitrogen == N neon==Ne magnesium == Mg
氧=O  氮=N  氖=Ne  镁=Mg
Some elements,which have been known for a long time,have symbols based on their Latin names, for example:
一些元素,很久以前就被知道的,它们的符号根据他们的拉丁名字符号,例如:
iron==Fe(ferrum)   copper==Cu(cuprum)  lead==Pb(plumbum)
铁= =Fe(ferrum)  铜= =Cu(cuprum)  铅= =Pb(plumbum)
A complete listing of the elements may be found in Table 1.reactive substance
一个完整的元素表可以被发现于表1。
Beginning in the late seventeenth century with the work of Robert Boyle, who proposed the presently accepted concept of an element, numerous investigations produced a considerable knowledge of the properties of elements and their compounds1. In 1869,D.Mendeleev and L. Meyer, working independently, proposed the periodic law. In modern form, the law states that the properties of the elements are periodic functions of their atomic numbers. In other words, when the elements are listed in order of increasing atomic number, elements having closely similar properties will fall at definite intervals along the list. Thus it is possible to arrange the list of elements in tabular form with elements having similar properties placed in vertical columns2. Such an arrangement is called a periodic table。
在十七世纪后期开始,在工作罗伯特·波以耳,提出当前公认的元素概念,大量的研究产生元素性质及其化合物的知识。在1869年,D.Mendeleev和L. Meyer,独立工作,提出了周期性的律法。在现代形式,法律规定的元素的性质是原子序数的周期函数。换句话说,当元素的按原子序数增加列清单，有相近的特性的元素落在了明确的间隔在清单上有明确间隔。于是，将具有类似性质的元素排成纵列，从而把元素排成表格形式是可能的。这样的安排被称为一个周期表。
Each horizontal row of elements constitutes a period. It should be noted that the lengths of the periods vary. There is a very short period containing only 2 elements, followed by two short periods of 8 elements each, and then two long periods of 18 elements each. The next period includes 32 elements, and the last period is apparently incomplete. With this arrangement, elements in the same vertical column have similar characteristics. These columns constitute the chemical families or groups. The groups headed by the members of the two 8-element periods are designated as main group elements, and the members of the other groups are called transition or inner transition elements.
每个水平排的横列元素构成一个周期。但应该注意的是周期不同长度的。非常短的周期只包含两种元素,后面跟着两个短周期每个含8元素,然后两个长周期每个由18个元素组成。下一个周期包含32元素,最后一个周期明显不完整的。这样的安排，元素在同一纵列有相似的特性。这些纵列构成化学家庭或组。为首的两个8元素周期的成员被选定作为主族元素，其他组的成员被称为过渡或内在过渡元素。
In the periodic table, a heavy stepped line divides the elements into metals and nonmetals. Elements to the left of this line (with the exception of hydrogen) are metals, while those to the right are nonmetals. This division is for convenience only; elements bordering the line—the metalloids-have properties characteristic of - both metals and nonmetals. It may be seen that most of the elements, including all the transition and inner transition elements, are metals.
在元素周期表中,沉重的阶梯的线把元素分为金属和非金属元素。那条线的左边(除氢)是金属,而那些右边是非金属矿物等。这条线划分只是为了方便。那些与分隔线相临近的元素——准金属，既有金属的性质，又有非金属的性质。可以看出，大部分的元素，是金属元素。
Except for hydrogen, a gas, the elements of group IA make up the alkali metal family. They are very reactive metals, and they are never found in the elemental state in nature. However, their compounds are widespread. All the members of the alkali metal family, form ions having a charge of 1+ only. In contrast, the elements of group IB —copper, silver, and gold—are comparatively inert. They are similar to the alkali metals in that they exist as 1+ ions in many of their compounds. However, as is characteristic of most transition elements, they form ions having other charges as well.
除了氢元素——一种气体元素外，ⅠA族的元素组成了碱金属。它们是非常活泼的金属，它们从未在自然界中以单质状态被发现。然而，它们的化合物是广泛分布的。碱金属的所有成员具有正一价的离子。与此相反，ⅠB族的元素铜、银、和金相对来说是惰性的。它们和碱金属的相似的，因为它们在化合物中以1+离子存在。但是和大多数过渡元素具有的特性一样，它们也能形成其它价的离子。
The elements of group IIA are known as the alkaline earth metals. Their characteristi
c ionic charge is 2+. These metals, particularly the last two members of the group, are almost as reactive as the alkali metals. The group IIB elements—zinc, cadmium, and mercury are less reactive than are those of group II A5, but are more reactive than the neighboring elements of group IB. The characteristic charge on their ions is also 2+.
ⅡA族的元素就是通常所说的碱土金属。它们离子的特征价是2+。这些金属，尤其是族中最后两个元素，几乎和碱金属一样活泼。ⅡB 族元素，锌、镉、和汞比那些ⅡA的元素活性低，但比临近的ⅠB族元素活泼。它们的特征价态也是2+。
With the exception of boron, group IIIA elements are also fairly reactive metals. Aluminum appears to be inert toward reaction with air, but this behavior stems from the fact that the metal forms a thin, invisible film of aluminum oxide on the surface, which protects the bulk of the metal from further oxidation. The metals of group IIIA form ions of 3+ charge. Group IIIB consists of the metals scandium, yttrium, lanthanum, and actinium.

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