问题 填空题

下表是元素周期表的一部分,请回答以下问题:

    主  族

周期

IAIIAIIIAIVAVAVIAVIIA0
      
   
      
(1)在这些元素中,最活泼的非金属元素是    (元素符号),原子最外层达到稳定结构的元素是(元素符号);

(2)元素的最高价氧化物对应的水化物中酸性最强的是        (填化学式);

(3)写出③、④的最高价氧化物对应的水化物相互反应的化学方程式

                                             

(4)③、⑥、⑧的原子半径由大到小为             (填元素符号),

①、⑤的最高价含氧酸酸性                 (均填化学式);

(5)写出证明非金属性⑥比⑨强(用置换反应证明)的化学方程式             

(6)写出工业上制备⑤单质的化学方程式                                  

答案

(16分)(1) F  Ar   (2) HClO4  (本题每空2分)

(3)    Al(OH)+ NaOH  = Na[Al(OH)4]

(4) K  ﹥Na﹥Cl; H2CO3 ﹥ H2SiO3或H4SiO4

(5)   2NaBr+Cl2=2NaCl+Br2      (6) SiO2 + 2CSi + 2CO ↑。

题目分析:①为C元素;②为F元素;③为Na元素;④为Al元素;⑤为Si元素;⑥为Cl元素;⑦为Ar元素;⑧为K元素;⑨为Br元素。

(1)(2)同周期,金属性自左向右金属性逐渐减弱,非金属性逐渐增强;同主族,金属性自上向下金属性逐渐增强,非金属性逐渐减弱。最活泼的非金属元素是F,原子最外层达到稳定结构的元素是Ar。元素的最高价氧化物对应的水化物中酸性最强的是HClO4

(3)③、④的最高价氧化物对应的水化物分别为NaOH、 Al(OH)3 ,其发生反应方程式为Al(OH)+ NaOH  = Na[Al(OH)4]。

(4)③、⑥属于同一周期,从左到右核电荷数依次增多,原子半径逐渐减小,即原子半径③>⑥;③、⑧属于同一主族,从左到右核电荷数依次增多,原子半径逐渐增大,即原子半径⑧>③,故原子半径大小数序为K ﹥Na﹥Cl。①、⑤的最高价含氧酸分别为H2CO3、H2SiO3或H4SiO4,因为C的非金属性大于Si的非金属性,故酸性强弱为H2CO3﹥ H2SiO3或H4SiO4

(5)比较非金属性的强弱,可以根据氢化物的稳定性、和氢气反应难易程度、最高价氧化物的水化物酸性的强弱、单质之间互相置换来比较。⑥为Cl元素,⑨为Br元素,可以通过置换反应来证明,方程式为2NaBr+Cl2=2NaCl+Br2

(6)⑤为Si元素,工业制取Si单质的化学方程式为SiO2 + 2CSi + 2CO ↑。

点评:本题考查学生根据元素周期表知识进行综合分析解题的能力,解题的关键是掌握有关元素周期表的规律。

名词解释
单项选择题

Remember the days when companies such as Microsoft and Mc-Kinsey took immense satisfaction from subjecting job candidates to mind-crunching strategy sessions If you thought that was rough, imagine an interview in which no amount of research or questioning of insiders will help. Imagine instead that all you can do is have a healthy breakfast, pick out your nicest suit, and hope for the best. In the new interview, they’re not just testing what you know. They’re also testing who you are.

It’s called the situational interview, and it’s quickly becoming a must in the job-seeking world. In the post-Enron culture of caution, corporations are focusing on an obvious insight: that a gold-plated resume and winning personality are about as accurate in determining job performance as Wall Street analysts are in picking stocks. Now, with shareholder scrutiny, hiring slowdowns, and expense-reducing, no manager can afford to hire the wrong person. Hundreds of companies are switching to the new methods. Whereas the conventional interview has been found to be only 7% accurate in predicting job performance, situational interviews deliver a rating of 54%—the most of any interviewing tool.

The situational technique’s superiority stems from its ability to trip up even the wittiest of interviewees. Of course, every applicant must display a healthy dose of occupational know-how, but behavior and ethical backbone play a big role. For example, a prospective analyst at a Wall Street bank might have to face, say, a customer with an account argument. It’s not happening on paper, but in real time—with managers and experts watching nearby. The interviewer plays the role of a fierce customer on the phone, angry about money lost when a trade wasn’t executed on time. It’s set up as an obvious mistake on the banker’s part.

Interviewers watch the candidates’ reactions: how they process the complex account information, their ability to talk the client down, what their body language displays about their own shortcomings, and which words they choose. In this instance, not being honest about the mistake or showing anger or frustration—no matter how glowing your resume—means you’re out.

Behavioral interviews are also being rounded out by other tools that, until recently, had been reserved for elite hires. Personality-testing outfit Caliper, for example, which probes candidates for emotional-intelligence skills and job ability, has seen its business jump 20% this year.

Clearly, the new interview isn’t without its drawbacks. Companies run the risk of arousing hostility in candidates, who may feel as if some line has been crossed into personal territory. Moreover, sortie companies worry about the fairness of personality tests. They have to make sure there are no inherent gender or racial biases in the test.

The advantages of behavioral interview include all of the following EXCEPT ().

A.it helps avoid employing the wrong personnel

B.it urges examinees on fully displaying expertise

C.it drives most candidates into feeling enmity

D.it stimulates testees to handle real-time problems