The nucleus in a carbon atom has six protons and six neutrons,each of which has the relative mass of 1.Therefore,the atomic mass of carbon is 12. In addition,a carbon atom has six electrons,but their weight is much less than that of the nucleus. 再问： 中文，谢谢，我会给你追加的 再答： 碳原子的原子核中有6个质子和6中子，每一个都具有为1的相对质量。因此，碳的原子量为12。 此外，碳原子有6个电子，但它们的重量远小于细胞核。
