您所在的当前位置：初中化学试题 >

原子结构

> 据英国《自然》杂志报道，科学家最近研制成了以锶原子做钟摆的“光晶格钟”，成了世界上最精确的钟．已知锶原子的相对原子质量为88，质子数为38，则中子数和电子数之差是 A.38 B.50 C.12 D.88

问题：

发布时间：2024-09-11

据英国《自然》杂志报道，科学家最近研制成了以锶原子做钟摆的“光晶格钟”，成了世界上最精确的钟．已知锶原子的相对原子质量为88，质子数为38，则中子数和电子数之差是

A.38
B.50
C.12
D.88

参考答案：

提问用户：EO***qtc

可能感兴趣的题目：

1 读我国某区域农业系统水、气、生相互作用图，完成3题。小题1:图中①②③所代表的环节分别是（） A．降水增加、大陆性增强、降水减少 B．地面蒸发的水量增多、气温变幅减小、降水增加 C．气温变幅减小、蒸发增强、降水增加 D．地下水位上升、气温变幅变大、土壤表层盐分积累（）小题2:该示意图可能表示的农业系统是 A．河谷农业 B．坝子农业 C．绿洲农业 D．立体农业小题3:该示意图体现了（） A．地理环境的地域分异 B．地理环境的整体性 C．自然环境的相对稳定性 D．人类对自然的改造力量是无穷的
2 （12分）如图所示．在国庆阅兵式中．某直升飞机在地面上空某高度 A位置处于静止状态待命。要求该机10时56分40秒由静止状态沿水平方向做匀加速直线运动,经过 AB段加速后,进入 BC段的匀速受阅区,1l时准时通过 C位置。已知 SAB＝5 km， SBC＝10 km。问： (1)直升飞机在 BC段的速度大小是多少? (2)在 AB段做匀加速直线运动时的加速度大小是多少?
3 已知| | =" 6," 与的夹角为60 0, ( + 2 )·( －3 ) = －72, 则| |为 A．5 B．16 C．5 D．4
4 --- Have you ___________ him to give up the job? ---Yes, I have. But he doesn’t listen to me. A．persuaded B．suggested C．advised D．agreed
5 在真空中的光滑水平绝缘面上有一带电小滑块。开始时滑块静止。若在滑块所在空间加一水平匀强电场E 1，持续一段时间后立即换成与E 1相反方向的匀强电场E 2。当电场E 2与电场E 1持续时间相同时，滑块恰好回到初始位置，且具有动能E k。在上述过程中，E 1对滑块的电场力做功为W 1，冲量大小为I 1；E 2对滑块的电场力做功为W 2，冲量大小为I 2，则（） A．I 1＝I 2 B．4I 1＝I 2 C．W 1＝0.25E k，W 2＝0.75E k D．W 1＝0.20E k，W 2＝0.80E k
6 阅读理解。 Last August, Joe and Mary Mahoney began looking at colleges for their 17-year-old daughter, Maureen. With a checklist of criteria in hand, the Dallas family looked around the country visiting half a dozen schools. They sought a university that offered the teenager"s intended major, one located near a large city, and a campus where their daughter would be safe. "The safety issue is a big one," says Joe Mahoney, who quickly discovered he wasn"t alone in his worries. On campus tours other parents voiced similar concerns, and the same question was always asked: what about crime? But when college officials always gave the same answer, "That"s not a problem here," --Mahoney began to feel uneasy. "No crime whatsoever?" comments Mahoney today. "I just don"t buy it." Nor should he: in 1999 the U.S. Department of education had reports of nearly 400,000 serious crimes on or around our campuses. "Parents need to understand that times have changed since they went to college," says David Nichols, author of Creating a Safe Campus. "Campus crime mirrors the rest of the nation." But getting accurate information isn"t easy. Colleges must report crime statistics by law, but some hold back for fear of bad publicity, leaving the honest ones looking dangerous. "The truth may not always be serious," warms S. Daniel Carter of Security on Campus, InC．, the nation"s leading campus safety watchdog group. To help concerned parents, Carter promised to visit campuses and talk to experts around the country to find out major crime issues and effective solutions. 1．The Mahoneys visited quite a few colleges last August ________. A．to express the opinions of many parents B．to choose a right one for their daughter C．to check the cost of college education D．to find a right one near a large city 2．It is often difficult to get correct information on campus crime because some colleges ______. A．receive too many visitors B．mirror the rest of the nation C．hide the truth of campus crime D．have too many watchdog groups 3．The underlined word " buy" in the third paragraph means __________. A．mind B．admit C．believe D．expect 4．We learn from the text that "the honest ones" in the fourth paragraph most probably refers to colleges _________. A．that are protected by campus security B．that report campus crimes by law C．that are free from campus crime D．that enjoy very good publicity 5．What is the text mainly about? A．Exact campus crime statistics B．Crimes on or around campuses C．Effective solutions to campus crime D．Concerns about kids" campus safety
7 已知程序框图如图所示，则执行该程序后输出的结果是______．
8 _____ways to be more gentle with the earth, or we’ll be punished. [ ] A. Found B. Finding C. Find D. To find
9 ________ are you doing this evening? A.How B.What C.When D.Where
10 下列关于原子结构的说法中，不正确的是 A.在原子中，核电荷数一定等于质子数或电子数 B.原子质量约等于原子核内质子和中子的质量之和 C.构成原子核必不可少的粒子是质子 D.任何原子都含有质子、中子和电子