<?xml version="1.0" encoding="utf-8"?><mads xmlns="http://www.loc.gov/mads/" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mads/
mads.xsd"><authority><topic authority="http://AATesaurus.cultura.gencat.cat/aat/getty_en">isotopes</topic></authority><related type="narrower"><topic>strontium isotopes</topic></related><related type="narrower"><topic>oxygen isotopes</topic></related><related type="narrower"><topic>nitrogen isotopes</topic></related><related type="narrower"><topic>lead isotopes</topic></related><related type="narrower"><topic>radioisotopes</topic></related><related type="narrower"><topic>neodymium isotopes</topic></related><related type="broader"><topic>materials by chemical form</topic></related><variant type="other"><topic>isotope</topic></variant> <note xml:lang="en"><![CDATA[ Forms of a chemical element having the same atomic number but different mass. An isotope is a form of a particular chemical element that shares with other forms the same number of protons in the nucleus, and thus the same atomic number and position in the periodic table, but differs from other forms in the number of neutrons, and therefore the atomic weight. ]]></note></mads>