atomic number
noun [ C ] chemistry specialized uk/əˌtɒm.ɪk ˈnʌm.bər/ us/əˌtɑː.mɪk ˈnʌm.bɚ/
原子数（某种化学物质的原子核中质子的数量，用于化学元素周期表中的排序）
the number of protons found in the nucleus of an atom of a particular chemical, used as a way of listing the chemical elements in order in the periodic table