万物简史 第147期:基本物质(19)

 　　The structure of atoms and the significance of protons will come in a following chapter, so for the moment all that is necessary is to appreciate the organizing principle: hydrogen has just one proton, and so it has an atomic number of one and comes first on the chart; uranium has ninety-two protons, and so it comes near the end and has an atomic number of ninety-two. In this sense, as Philip Ball has pointed¹ out, chemistry really is just a matter of counting. (Atomic number, incidentally, is not to be confused with atomic weight, which is the number of protons plus the number of neutrons² in a given element.) There was still a great deal that wasn’t known or understood.

　　有关原子的结构和质子的意义，我们将在下一章加以叙述。眼下，我们只来认识一下那个排列原则：氢只有一个质子，因此它的原子序数是1，排在表上第一位；铀有92个质子，因此快要排到末尾，它的原子序数是92。在这个意义上，正如菲利普?鲍尔指出的，化学实际上只是个数数的问题。（顺便说一句，不要把原子序数和原子量混在一起。原子量是某个元素的质子数加中子数之和。）还有大量的东西人们不知道或不懂得。

　　化学元素

　　Hydrogen is the most common element in the universe, and yet no one would guess as much for another thirty years. Helium, the second most abundant element, had only been found the year before—its existence hadn’t even been suspected before that—and then not on Earth but in the Sun, where it was found with a spectroscopeduring a solar eclipse, which is why it honors the Greek sun god Helios. It wouldn’t be isolated³ until 1895. Even so, thanks to Mendeleyev’s invention, chemistry was now on a firm footing.

　　宇宙中最常见的元素是氢；然而，在后来的30年里，对它的认识到此为止。氦是第二多的元素，是在此之前一年才发现的--以前谁也没有想到它的存在--而即使发现，也不是在地球上，而是在太阳里。它是在一次日食时用分光镜发现的，因此以希腊太阳神赫利奥斯命名。直到1895年，氦才被分离出来。即使那样，还是多亏了门捷列夫的发明，化学现在才站稳了脚跟。

1 pointed   

adj.尖的，直截了当的

参考例句：

• He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
• She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。

2 neutrons   

n.中子( neutron的名词复数 )

参考例句：

• The neutrons and protons form the core of the atom. 中子和质子构成了原子核。 来自《简明英汉词典》
• When an atom of U235 is split,several neutrons are set free. 一个铀235原子分裂时，释放出几个中子。 来自《简明英汉词典》

3 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。