问题 填空题

(8分)现有部分短周期元素的性质或原子结构如下表:

元素编号元素性质或原子结构
TM层上有2对成对电子
X最外层电子数是次外层电子数的2倍
Y常温下单质为双原子分子,其氢化物水溶液呈碱性
Z元素最高正价是+7价
(1)元素T的原子最外层共有______种不同运动状态的电子。元素X的一种同位素可测定文物年代,这种同位素的符号是_________。

(2)元素Y与氢元素可形成离子YH,YH离子的结构式为     

(3)元素Z与T相比,非金属性较强的是_______(填元素名称),下列表述中能证明这一事实的是________。

a.常温下Z的单质和T的单质状态不同   

b.Z的氢化物比T的氢化物稳定

c.一定条件下Z和T的单质都能与氢氧化钠溶液反应

d.Z更易与H2化合

e.Z和T均可与铁化合,但Fe在与Z生成的化合物中价态更高

(4)写出两种由上述某两种元素组成的非极性分子的结构式     

                             

答案

(8分)(1)6  C   (2)   

(3)氯    bde   (4)S=C=S   

根据元素的结构及应该性质可知,T是S,X是C,Y是N,Z是Cl。

(1)硫元素的最外层电子数是6个,所以有6种不同运动状态的电子。用于测定文物年代的是

(2)该离子是NH4,含有配位键,其结构式为

(3)非金属性的比较规律:

1、由元素原子的氧化性判断:一般情况下,氧化性越强,对应非金属性越强。

2、由单质和酸或者和水的反应程度判断:反应越剧烈,非金属性越强。

3、由对应氢化物的稳定性判断:氢化物越稳定,非金属性越强。

4、由和氢气化合的难易程度判断:化合越容易,非金属性越强。

5、由最高价氧化物对应水化物的酸性来判断:酸性越强,非金属越强。(除氟元素之外)

6、由对应阴离子的还原性判断:还原性越强,对应非金属性越弱。

7、由置换反应判断:强置弱。〔若依据置换反应来说明元素的非金属性强弱,则非金属单质应做氧化剂,非金属单质做还原剂的置换反应不能作为比较非金属性强弱的依据〕

值得注意的是:氟元素没有正价态,故没有氟的含氧酸,所以最高价氧化物对应水合物的酸性最强的是高氯酸,而不是非金属性高于氯的氟元素!故规律5只适用于氟元素之外的非金属元素。

8、按元素周期律,同周期元素由左到右,随核电荷数的增加,非金属性增强;同主族元素由上到下,随核电荷数的增加,非金属性减弱。

9. 非金属单质与具有可变价金属的反应。能生成高价金属化合物的,其非金属性强。

据此可判断选项bde是正确的。

(4)由上述某两种元素组成的非极性分子分别是CS2和CCl4,其结构式为S=C=S、   

单项选择题

In 1998 consumers could purchase virtually anything over the Internet. Books, compact discs, and even stocks were (1) from World Wide Websites that seemed to (2) almost daily a few years earlier, some people had predicted that consuners accustomed to shopping in stores would be (3) to buy things that they could not see or touch (4) . For a growing number of time-starved consumers, however, shopping from their home computer was proving to be a convenient (5) to driving to the store.

A research estimated that in 1998 US consumers could purchase $ 7.3 billion of goods over the Internet, double the 1997 total. Finding a bargain was getting easier, (6) the rise of online auctions and Websites that did comparison shopping on the Internet for the best (7) .

For all the consumer interest, (8) in eyberspaee was still a largely (9) business, however. Internet pioneer Amazon. eom, which began selling books in 1995 and later (10) into recorded music and videos, posted (11) of $ 153.7 million in the third quarter, up from $ 37.9 million in the same period of 1997. Overall, (12) , the company’ s loss widened to $ 45.2 million from $9.6 million, and analysts did not expect the company to turn a profit (13) 2001. (14) the great loss, Amazon. tom had a stock market value of many billions, reflecting investors’ (15) about the future of the industry.

Internet retailing appealed (16) investors because it provided an efficient means for reaching millions of consumers without having the cost of operating (17) stores with their armies of salespeople. Selling online carried its own risks, however, (18) so many companies competing tor consumers’ attention, price competition was (19) and profit (20) thin or nonexistent.

6()

A. in spite of

B. owing to

C. according to

D. in the light of

单项选择题