(10分)1932年美国化学家鲍林首先提出了电负性的概念。电负性(用X表示)也是

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问题:

(10分)1932年美国化学家鲍林首先提出了电负性的概念。电负性(用X表示)也是元素的一种重要性质,下表给出的是原子序数小于20的16种元素的电负性数值:

请仔细分析,回答下列有关问题:

①预测周期表中电负性最大的元素应为_____;估计钙元素的电负性的取值范围:        < X <           

②根据表中的所给数据分析,同主族内的不同元素X的值变化的规律是             

                              ; 简述元素电负性X的大小与元素金属性、非金属性之间的关系                                                                       

③经验规律告诉我们:当形成化学键的两原子相应元素的电负性差值大于1.7时,所形成的一般为离子键;当小于1.7时,一般为共价键。试推断AlBr3中形成的化学键的类型为                

考点:构成物质的粒子—分子、原子、离子元素周期律
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下列符号中,表示2个钠离子的是[ ]

A.2N

B.2Na

C.Na 

D.2Na+

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ETF规模的变动最终取决于折、溢价套利机会的多少。()

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All her life, my mother wanted busy children. It was very important that her house should remain at all times clean and tidy.
You could turn your back for a moment in my mother’s house, leave a half written letter on the dining table, a magazine open on the chair, and turn around to find that my mother had "put it back where it belonged," as she explained. My wife, on one of her first visits to my mother’s house, placed a packet of biscuits on an end table and went to the kitchen to fetch a drink. When she returned, she found the packet had been removed. Confused, she set down her drink and went back to the kitchen for more biscuits, only to return to find that her drink had disappeared. Up to then she had guessed that everyone in my family held onto their drinks so as not to make water rings on the end tables. Now she knows better.
These disappearances had a confusing effect on our family. We were all inclined to forgetfulness, and it was common for one of us, upon returning from the bathroom, to find the every sign of his work in progress had disappeared suddenly. "Do you remember what I was doing" was a question frequently asked, but rarely answered.
Now my sister has developed a secondhand love of clean windows, and my brother does the cleaning in his house, perhaps to avoid having to be the one to lift his feet. I try not to think about it too much, but I have at this later time started to dust the furniture once a week.

Which of the following is TRUE about my mother

A.She enjoyed removing others’ drinks.
B.She became more and more forgetful.
C.She preferred to do everything by herself.
D.She wanted to keep her house in good order.

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苍术饮片暴露稍久后,所含的β-桉油醇成分析出的结晶,呈毛状,色白如脂霜,称为()

A.皮刺

B.过桥

C.白心

D.尖蒂

E.吐脂

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应急消防泵是在()等处出现火情事故,则要启动应急柴油消防泵。()。

A、出现火情和厨房

B、出现火情和电站

C、厨房和电站

D、电站和生活楼

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