首页
财务会计
医药卫生
金融经济
考公考编
外语考试
学历提升
职称考试
建筑工程
IT考试
其他
登录
职称考试
Learn about Noble Gases (惰性气体) 1 Have you ever ridden on a balloon? Many tou...
Learn about Noble Gases (惰性气体) 1 Have you ever ridden on a balloon? Many tou...
admin
2020-12-24
36
问题
Learn about Noble Gases (惰性气体)
1 Have you ever ridden on a balloon? Many tourist spots offer balloon rides in order for people to see the beauty of a place from above. A balloon contains a noble gas called helium (氦). Formerly, balloons contained hydrogen but hydrogen is very flammable and dangerous when uncontrolled- Therefore, people shifted to helium, which is safer. Helium is safe because it has the properties of the noble gases.
2 People once believed that noble gases couldn’t chemically react at all. For this reason, they were called inert gases (惰性气体).They were also listed under Group 0 in the old periodic table because scientists believed that the gases have zero valence (价)electrons in their outer shell. This was later proven to be untrue when some noble gas compounds were discovered.
3 The gases are elements, which share similar properties. These properties include being monatomic, colorless, odorless, being able to conduct electricity, and having low chemical reactivity. Noble gases include Helium, Neon, Argon, Krypton, Xenon and Radon. These are all found in Group 18, in the rightmost column of the periodic table. If you look at the periodic table, you will notice that these elements are the only ones, which do not have a charge. Helium has the lowest molecular (分子的)weight while Radon is the heaviest.
4 Remember that chemical reactions occur because atoms have valence electrons, which are electrons in their outer shell. When the outer shell is "unfilled" or the required number of electrons is not yet complete, the atom is more reactive. Noble gases have a full outer shell, meaning that they have complete electrons in their outer shell. This complete number varies. For instance, the outer shell of Helium has 2 valence electrons while the outer shell of Xenon has 8 electrons. Nowadays, there remains to be a few noble gases because of the low chemical reactivity of these said gases.
5 Because of their properties, noble gases have many important applications. They are widely used in medicine and industries. For instance, liquid Helium is used for superconducting magnets (磁体).These magnets are very important in physics and medicine. When a doctor suspects that a person’s brain has been damaged, he might request for Magnetic Resonance Imaging (MRI) . MRI allows the doctor to "see" the brain, without operating on the patient.
Among the elements of noble gases Helium is the .
选项
A lightest
B reactive
C important
D complete
E flammable
F unnecessary
答案
A
解析
根据第三段最后一句:Helium has the lowest molecular (分子的) weight...
转载请注明原文地址:https://ti.zuoweng.com/ti/LZsQKKKQ
相关试题推荐
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manyto...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?spotso行...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?spotso行...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?spotso行...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?spotso行...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
随机试题
根据下面资料,回答 Igrewupinacommunitycall
可出现原位溶血的疾病是
下列有关会计方面的表述中,不正确的是()。
男,20岁。感冒后7天出现颜面及双下肢浮肿,尿少。查:血压160/100mmHg
2005-35.下列选项中,能解表消疮的药物是 A.防风B.荆芥C.细辛
下列关于固定资产重置的表述正确的有()。A.固定资产重置的原因主要是设备自然老化和技术更新B.与公司管理层进行必要的沟通,有助于了解固定资产重置的需求和计划
()是招标单位行动的指南,也是投标企业必须遵循的原则。A.招标申请书B.招标邀请书C.招标文件D.标书
人造防眩设施主要包括()。A.防眩叶B.防眩板C.防眩网D.防眩球E.防眩桶
当被征收房屋被认定为违法建筑或超过批准期限的临时建筑,可以进行征收估价,只是评估价值要进行减价调整。()
生产经营者通过套期保值并不能消除风险,只能将风险转移〔〕。