We measure atomic mass in atomic mass units.

我们以原子质量单位测量原子质量。

But the relative atomic mass does change.

但是相对原子质量确实发生了变化。

The same goes for atomic mass. We measure atomic mass in atomic mass units.

原子质量也是如此。 我们以原子质量单位测量原子质量。

For instance, the mass of a neutral helium atom is 4.002603 unified atomic mass units.

一个稳定的氦原子核的质量是4。002603u。

The relative atomic mass, then, ends up being about halfway between 107 and 109, 107.8682.

然后，相对原子质量最终约为 107 和 109 之间的一半， 即 107. 8682。

The real coin of the realm when it comes to measuring stuff in chemistry is relative atomic mass.

在测量化学中的东西时， 真正的硬币是相对原子质量。

Which means that carbon has a relative atomic mass of 12.01 amu.

这意味着碳的相对原子质量为 12. 01 amu。

The mass number is just the total number of nucleons in the nucleus, which is different from atomic mass.

质量数只是原子核中核子的总数， 它不同于原子质量。

So the relative atomic mass of carbon is a weighted average of these three masses, which comes out to 12.01.

所以碳的相对原子质量是这三个质量的加权平均值， 结果为 12. 01。

That means that the nucleus of a helium atom has 0.030377 unified atomic mass units less mass than its component parts.

这意味着氦原子核的质量比其组成部分少 0.030377 个统一原子质量单位。