问题 填空题

氯化硼(BN)晶体是一种新型无机合成材料。用硼砂(Na2B4O7)和尿素反应可以得到氮化硼:Na2B4O7+ 2CO(NH2)2=4BN+Na2O +4H2O+2CO2↑,根据要求回答下列问题:

(1)组成反应物的所有元素中,第一电离能最大的是___________________。

(2)尿素分子()中键与键数目之比为__________;尿素分子中处于同一平面的原子最多有_______个。

(3)尿素分子一定条件下形成六角形“超分子”(结构如图)。“超分子”中尿素分子间主要通过什么作用力结合。答:________________(填1种)。

(4)图示“超分子”的纵轴方向有一“通道”。直链烷烃分子刚好能进人通道,并形成“超分子”的包台物;支链烷烃因含有测链,空间体积较大而无法进入“通道”。利用这一性质可以实现直链烷烃和支链烷烃的分离。

①直链烷烃分子能进人通道时,通过什么作用力与“超分子”结合,从而形成 “超分子”包合物?答:___________________。

②下列物质可以通过尿素“超分子”进行分离的是____________。

A.乙烷和丁烷    B.丁烷和异丁烷    C.异戊烷和新戊烷    D氯化钠和氯化钾

(5)BN晶体有a、B两种类型,且a—BN结构与石墨相似、B—BN结构与金刚石相似。

①a一BN晶体中N原子杂化方式是____________________;

②B—BN晶体中,每个硼原予形成________个共价键。这些共价键中,有________个为配位键。

答案

(1)N(2分)

(2)1︰7(2分)   6(2分)

(3)氢键(2分)

(4)①范德华力(1分) ②B(1分)

(5)①sp2(1分)   ②4    1(各1分,共2分)

题目分析:(1)组成反应物的所有元素Na、B、O、C、N、H,非金属性越强第一电离能越大。但由于氮元素的2p轨道电子处于半充满状态,稳定性强,所以氮元素的第一电离能大于氧元素的,即组成反应物的所有元素中,第一电离能最大的是N。

(2)单键都是键,双键是由1个键和1个键构成的,所以根据尿素分子的结构简式可知,分子中键与键数目之比为1︰7;由于碳氧双键是平面形结构,2个氮原子位于这个平面上。由于氨气是三角锥形结构,因此氨基中的2个氢原子最多有1个位于这个平面上,因此尿素分子中处于同一平面的原子最多有6个。

(3)尿素形成的晶体是分子晶体,而氧元素与氮元素均能形成氢键,所以“超分子”中尿素分子间主要通过氢键作用力结合。

(4)①烷烃形成的晶体类型是分子晶体,因此通过分子间作用力即范德华力与“超分子”结合,从而形成 “超分子”包合物。

②关节炎题意可知,可以实现直链烷烃和支链烷烃的分离,而乙烷和丁烷都不带支链,异戊烷和新戊烷均带支链,氯化钠和氯化钾不是烷烃,因此不能实现分离,丁烷和异丁烷分别是直链烷烃和支链烷烃,可以实现分离,答案选B。

(5)①a—BN结构与石墨相似,而石墨是层状结构,碳原子是sp2杂化,所以a一BN晶体中N原子杂化方式是sp2杂化。

②B—BN结构与金刚石相似,金刚石中每个碳原子形成4个共价键,所以B—BN晶体中,每个硼原予也形成4个共价键。由于B原子的最外层电子数是3个,只能形成3个共价键,因此这些共价键中,有1个为配位键。

选择题
阅读理解

“Racism (种族歧视) is a grown-up disease,” declares the saying on Ruby Bridge’s website along with a photo of Mrs. Bridge today, a 6-year-old girl four decades ago. In the photo, she is walking up the steps of the William Frantz Public School in New Orleans, a little black girl accompanied by two officers who protect her on her way to school.

Her name then was Ruby Nell. It was Nov. 14, 1960. She was the first black child to enroll at this all-white elementary school according to the court order to desegregate in New Orleans schools. Her story is moving -- she was a very courageous child -- and remains a significant proof against intolerance (不宽容) of all kinds. Ruby’s photo brings out another powerful image on her website: Norman Rockwells symbolic painting for Look magazine on Jan. 14, 1964, “The Problem We All Live With.”

Rockwell was an illustrator of exceptional skill and charm. He produced a vast number of unforgettable images over a long career, many of them involving children. His American kids are innocent and appealing, but often, at the same time, decidedly naughty. His method was to photograph his models, and the resulting paintings were photographic. But it is revealing to see how the artist slightly changed facial expressions from photo to oil painting in order to make his paintings communicate with the viewer. Communication, even persuasion, lay at the back of his work; this was art for effect.

“The Problem We All Live With” belongs to Rockwell’s later work, when he began openly showing his strong belief in liberty. This is a highly persuasive image. Before he arrived at the final copy, one sketch (草图) shows the little girl closer to the two officers following her than to those in front. In the finished picture, the girl seems more determined, independent, and untouched. The unfriendly tomatoes thrown on the wall are behind her now, and she, is completely unaffected.

小题1:Ruby Nell was protected by officers on her way to school, because   .

A.she was a little fighter against racism

B.she was very young, short and timid

C.she was the first black to study in an all-white school

D.she was chosen by the com t0be’wi’th white children小题2:According to the passage, “The Problem We All Live With” is a(n)     .

A.social program for American children

B.famous painting by Norman Rockwell

C.photo displayed on Ruby Bridges’ website

D.exhibition at the Norman Rockwell Museum小题3:The word “desegregate” in paragraph 2 probably means“   ”.

A.fight against the white

B.end racial separation

C.struggle for freedom

D.stop the black-white conflict小题4:The main topic of this passage is   .

A.how Rockwell encouraged Ruby to fight against racism

B.how Ruby won her fight to go to an all-white school

C.how Rockwell expressed his protest in .Iris work

D.how persuasive Rockwell’s earlier work of art is