1. The Elements and The Periodic Table
元素和周期表
The number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, Z. The numbers 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 of the number, A. The number of neutrons in an atom, the neutron number, is given by the quantity A-Z.
refer to sb. [sth.] as 称某人（物）为
be determined by 由…确定
原子核中质子的数目称为原子序数，或者质子数，以Z表示。电中性原子中电子的数目也等于原子序数Z。经测定，原子的总质量与原子核中质子与中子的总数差不多。（几乎相同）（或者说原子的总质量几乎可以由原子核中质子与中子的总数确定。）这个总数叫质量数，以A表示。因此，原子中的质子的数目，质子数，可以定量地由A-Z给出。即原子中质子数=A-Z
The term element refers to a pure substance with atoms all kinds of a single kind. To the chemist the “kin
d” of an 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:
元素这个术语指的是仅仅由同一种类的原子组成的物质。对化学家（化学工作者）来说，原子的种类由原子序数决定（表示），因为这是决定它的化学表现（行为）的性质。现在已经发现了原子序数Z=1到Z=107的所有原子；这些是107种化学元素。每一种化学元素都被赋予了一个名字和一个特有的（与众不同的）符号。对大部分元素来说，这个含有一个或两个字母的符号仅仅是英文名字的缩写形式，例如：
specify by 用…说明（表示）
Oxygen=O nitrogen=N neon=Ne magnesium=Mg
Some elements; which have been known for a long time, have symbols based on their Latin names, for example:
另外有些早已为人所知的元素的符号是拉丁文名字的缩写（是建立在拉丁文名字的基础上的），例如：
Iron（英文名字）=Fe（缩写）(ferrum)（拉丁文名字）copper=Cu(cuprum) lead=Pb(plumbum) A complete listing of the elements may be found in Table 1.
更完整的元素列表（清单）见表1。
Beginning in the late seventeenth century with the work of Robert Boyle （罗伯特 波义耳，英国化学家，物理学家）, who proposed the presently accepted concept of an element, numerous investigations produced a considerable knowledge of the properties of elements and their compounds. 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 columns. Such an arrangement is called a periodic table.
早在17世纪末期，罗伯特 波义耳就开始了这项工作，他提出了现在公认的元素概念，大量的研究使我们
对元素极其化合物的性质有了相当的了解。1869年，D. Mendeleev 和L. Meyer 在各自工作的基础上，分别提出了元素周期律。用现代的话说，这个规律叙述了元素的性质是它们的原子序数的周期性函数。换句话说，当元素按照原子序数逐渐递增的顺序列表（排列时），性质非常接近的元素将占据表格中具有一定间隔的位置。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。这样的排列形式就叫做元素周期表。
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 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.
It shoud be noted that.应当注意的是
（在元素周期表中），水平的每一排元素组成了一个周期。应当注意的是，周期的长短
是有变化的。首先是一个含有2种元素的极短周期，接着是两个短周期，每一周期含有8种元素，然后是
各有18种元素的两个长周期，再下一个周期含有32种元素，最后一个周期显然是不完整的（尚未完全发现）。在这种排列下，处于同一纵列的元素具有相似的性质。这些纵列就组成了元素周期表中的族。由两个8元素周期中的元素开头的族被指定为主族元素，其它族的元素叫过度元素或内过度元素。
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 characteristics of both metals and nonmetals. It may be seen that most of the elements, including all the transition and inner transition elements, are metals.
在周期表中，一条粗的阶梯状的线把元素划分为金属元素和非金属元素。处于线左边的元素（H元素除外）是金属元素，而处于线右边的元素是非金属元素。这种分法仅仅是为了方便。靠近线两边的元素-准金属元素-同时具有金属和非金属元素的性质特征。可以看出，大部分元素，包括过度元素和内过度元素，都是金属元素。
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 element 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 cont
reactive substancerast, 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，一种气体之外，IA元素构成了碱金属家族。它们是极其活泼的金属，在自然界中从来没有发现它们的单质状态。但是，它们的化合物却分布广泛。碱金属家族的所有成员都仅仅形成带1个正电荷的离子。相反，IB的元素-铜，银和金却相对惰性。与碱金属相似，它们也以1+离子形式存在于许多化合物中。但是，象许多过度元素所具有的特点一样，它们也形成具有其它电荷的离子。
The elements of group IIA are known as alkaline earth metals. Their characteristic 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-zinc, cadmium, and mercury are less reactive than are those of group IIA, but are more reactive than the neighboring elements of group IB. The characteristic charge on their ions is also 2+.
IIA元素被称为碱土金属元素。它们的特征离子电荷为2+。这些金属，尤其是这一族的最后两个成员，几乎和碱金属一样活泼。IIB元素-锌，镉，汞不如IIA元素活泼，但是比相邻的IB的元素活泼得多。它们的离子的特征电荷也是2+。
With the exception of boron，group IIIA elements are a1so fairly reactive metals．Aluminum appears to be inert toward reaction with air，but this behavior stems from（来源于，起源于）the fact that the metal forms a thin, invisible film of aluminum oxide on the surface, which protects the bulk of（大量，大多数）the metal from further oxidation．The metals of group IIIA form ions of 3+ charge. Group IIIB consists of the metals

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