问题 选择题

具有下列电子层结构的原子和离子,其对应的元素一定属于同一周期的是(  )

A.两原子的核外全部都是s电子

B.最外层电子排布为2s22p6的原子和最外层电子排布为2s22p6的离子

C.原子核外M层上的s、p轨道都充满电子,而d轨道上没有电子的两种原子

D.两原子N层上都有1个s电子,一个原子有d电子,另一个原子无d电子

答案

A、两原子的核外全部都是s电子,原子具有1s能级或具有1s、2s能级,不处于同一周期,如氢原子与锂原子,故A错误;

B、最外层电子排布为2s22p6的原子为氖原子,最外层电子排布为2s22p6的离子可能是阴离子也可能是阳离子如O2-、Na+等,故B错误;

C、原子核外M层上的s、p轨道都充满电子,而d轨道上没有电子,符合条件的原子的核外电子排布式有1s22s22p63s23p6为氩原子,1s22s22p63s23p64s1为钾原子,1s22s22p63s23p64s2为钙原子,不一定处于同一周期,故C错误;

D、原子N层上都有1个s电子,原子无d电子为K原子,原子有d电子为1s22s22p63s23p63d54s1,是Cr原子,1s22s22p63s23p63d104s1,是Cu原子,都处于第四周期,故D正确.

故选D.

阅读理解

阅读理解。

     It took me three long and hard years to get a lovely little dog named Dion.

     My family and I met it at a dog show. We drove for four hours to its owner's house where she showed

us three little dogs, two males and one female. They were so lovely with their little legs, long bodies and heads

that looked too big for their bodies. It took me a long time to decide which one I wanted,but I finally decided

when the female came up to me and licked (舔) my face.

     My mother and I took Dion to a kindergarten (幼稚园) for little dogs. She was very shy and hid from

people. But she was very friendly with the other dogs.

     If you want to get a dog, think about your time and the work you must do. I walk Dion four to six times

a day. I feed her, spend time with her and watch her when she is out of her doghouse. Even if my favorite TV

program is on, or a good part in a movie is coming up, I still have to take care of her. It is a lot of work to

keep her clean. Sometimes when I brush her I end up with hair all over me.

     But I think it is all worth it. Dion also gives her love to me in return. She is always there to lick me and lie

on me. I like playing with her. I think she can tell when I am happy, sad, angry or troubled. Dion is not only

my dog, but she is also my friend.

1. What does Dion look like?

   

2. The writer finally decided to take Dion because _____.

A. it was very clean

B. it was the youngest one

C. it was very quiet

D. it was friendly to him

3. Paragraph 4 tells us that keeping a dog is a _____ job.

A. hard

B. funny

C. popular

D. dirty

单项选择题