Scientific term for atoms of the same element with different numbers of neutrons.
炭素14は炭素の同位元素です。
Carbon-14 is an isotope of carbon.
Synonym for 'isotope'; 同位体 is more common in modern scientific contexts, while 同位元素 is slightly more formal or older.
radioisotope; radioactive isotope
Compound of 同位 (same position) and 元素 (element), referring to atoms occupying the same place in the periodic table.