化学专业英语翻译2

02.

THE NONMETAL ELEMENTS

We noted earlier. that -nonmetals exhibit properties that are greatly

different

from

those

of

the

metals.

As

a

rule,

the

nonmetals

are

poor

conductors of electricity (graphitic carbon is an exception) and heat; they

are brittle, are often intensely colored, and show an unusually wide range

of

melting

and

boiling

points.

Their

molecular

structures,

usually

involving

ordinary

covalent

bonds,

vary

from

the

simple

diatomic

molecules of H

2

, Cl

2

, I

2

, and N

2

to the giant molecules of diamond, silicon

and boron.

我们前面提到的。

-

非金属表现出的性 质有很大的不同，

这

些金属。作为一项规则，非金属都是热的不 良导体电（石墨碳是个例

外）和热；他们是脆的，往往是强烈的色彩，并显示一个非常广 泛的

熔点和沸点。其分子结构，

通常涉及一般共价键，从简单的 双原子分

子氢，氯，碘，和氮气的大分子的金刚石，硅和硼。

The

nonmetals

that

are

gases

at

room

temperature

are

the

low- molecular weight diatomic molecules and the noble gases that exert

very small intermolecular forces. As the molecular weight increases, we

encounter

a

liquid

(Br

2

)

and

a

solid

(I

2

)

whose

vapor

pressures

also

indicate

small

intermolecular

forces.

Certain

properties

of

a

few

nonmetals are listed in Table 2

非金属，

在室温下是气体的分子量和双原子分子的惰性气体，

< br>施加很

小的分子间力。

随着分子量增大，

我们遇到一个液体

（溴）

和固体

（碘）

的蒸气压力也表明小分子间力。某些性能的几个非列于表

2

Simple diatomic molecules are not formed by the heavier members of

Groups V and VI at ordinary conditions. This is in direct contrast to the

first members of these groups, N

2

and O

2

. The difference arises because of

the lower stability of

π

bonds formed from

p

orbitals of the third and higher

main energy levels as opposed to the second main energy level

2

. The larger

atomic

radii

and

more

dense

electron

clouds

of

elements

of

the

third

period

and

higher

do

not

allow

good

parallel

overlap

of

p

orbitals

necessary for a strong

π

bond. This is a general phenomenon

—

strong

π

bonds

are

formed

only

between

elements

of

the

second

period.

Thus,

elemental nitrogen and oxygen form stable molecules with both

σ

and

π

bonds,

but

other

members

of

their

groups

form

more

stable

structures

based

on

σ

bonds

only

at

ordinary

conditions.

Note

3

that

Group

VII

elements

form

diatomic

molecules,

but

π

bonds

are

not

required

for

saturation of valence.

简单的双原 子分子没有形成较重的群体成员的第五和第六在普通条

件。这是在直接对比的第一个成员 的这些群体，氮气和氧气。差异是

因为较低的稳定的

π

债券形成轨道的第三个及以上的主要能量水平

相对于第二主要能源。

较大的原子半径和更密集的电子云的第三周期

元素和较高的不允许平 行重叠的轨道需要一个强大的

π

债券。这是

一个普遍现象的

π

债券形成的唯一的元素之间的二期。因此 ，氮元

素和氧形成稳定的分子与

σ

和< /p>

π

债券，但其他成员的团体形成更稳

定的结构的基础上

σ

债券只在普通条件。

注

3

，< /p>

第七族元素形成双原

子分子，但

π

债券不需要饱和价。

Sulfur

exhibits

allotropic

forms.

Solid

sulfur

exists

in

two

crystalline forms and in an amorphous form. Rhombic sulfur is obtained

by

crystallization

from

a

suitable

solution,

such

as

CS

2

,

and

it

melts

at

112°

C. Monoclinic sulfur is formed by cooling melted sulfur and it melts at

119°

C.

Both

forms

of

crystalline

sulfur

melt

into

S-gamma,

which

is

composed

of

S

8

molecules.

The

S

8

molecules

are

puckered

rings

and

survive heating to about 160°

C. Above 160°

C, the S

8

rings break open, and

some of these fragments combine with each other to form a highly viscous

mixture of irregularly shaped coils. At a range of higher temperatures the

liquid sulfur becomes so viscous that it will not pour from its container.

The color also changes from straw yellow at sulfur's melting point to a

deep reddish-brown as it becomes more viscous.

硫展品同素异形体。

固硫存在

2

晶体形式和非晶态形式。

正交硫是通

过结晶从一个合适的解决方案，如二硫化碳，它融化在

112

摄氏

°

单

斜硫是由冷却熔化的 硫和它融化在

119°

C

两种形式的结 晶硫磺熔化

成

s-gamma

，由

8

分子。级分子折叠环和生存加热至约

16 0°

C .160

以上

°

，级环打开，其中一些片段相互结合，形成高粘度混合物的不

规则形线圈。< /p>

在一系列的温度较高的液体硫成为粘性，

它不会从容器。