Now, to get to the number of neutrons, what we do is go up here to the upper left.
现在,看看中子数,我们要做的,是看到这左上方。
This means you can vary the neutron number without changing chemical identity, because chemical identity is fixed by the proton.
这表示你可以改变中子数,而不会改变它的化学特性,因为化学特性是由质子决定的。
Now the last thing is that because the neutron has no net charge, we can change neutron number.
现在,最后一件事是,因为中子没有净电子,我们可以改变中子数。
So carbon 12. We know that it has the proton number, by definition, is 6. And the neutron number, 6 from 12 is 6. So it has 6 protons and 6 neutrons.
所以碳12,我们知道它有质子数,根据定义,那就是6,而电子数,12减6等于6,所以它有6个中子。
And it is equal to the sum of the number of protons plus the number of neutrons.
它等于质子数,加上中子数。
So we get at the number of neutrons indirectly because we know the proton number here.
所以,我们可以间接得到中子数,因为我们知道质子数了。
This is sum of protons plus neutrons.
它是质子数加上中子数。
They all have the same Z, the same proton number, but different A, which means number of neutrons varies.
有相同的Z,相同的质子数,但是不同的A,也就是中子数不同。
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