{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.cerium","code":"thing-q1385","url":"https://ver.cy/models/thing/q1385/","name":"cerium","alternateNames":["cerium-119","cerium-120","cerium-121","cerium-122","cerium-123","cerium-124","cerium-125","cerium-126","cerium-127","cerium-128","cerium-129","cerium-130"],"kind":"thing","status":"published","version":"0.2.0-wave.3","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.MAT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"A chemical element with symbol Ce and atomic number 58, a soft, ductile, silvery lanthanide and the most abundant rare earth element, which oxidises readily and shows both trivalent and tetravalent chemistry; cerium is used in catalytic converters, glass polishing, lighter flints and self-cleaning ovens, is recovered from monazite and bastnasite, and has four naturally occurring isotopes, of which three are stable and cerium-142 is radioactive.","purpose":"Let an agent identify cerium and its properties, relay production, uses, isotopes and history from reference sources, relay safety information, and distinguish it from neighbouring lanthanides.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Most abundant rare earth","Tetravalent chemistry","Pyrophoric alloys","Catalytic oxide"],"structure":{"bundles":[{"id":"identify","name":"Identify","description":"What cerium is.","layers":[{"id":"properties","name":"Properties","description":"Properties.","findings":[{"id":"properties-finding","name":"Properties","description":"Properties.","questions":[{"text":"What are the physical and chemical properties of cerium, including its two oxidation states?","kind":"definition"},{"text":"Is the question about cerium or a neighbouring lanthanide?","kind":"boundary"}]}]},{"id":"isotopes","name":"Isotopes","description":"Isotopes.","findings":[{"id":"isotopes-finding","name":"Isotopes","description":"Isotopes.","questions":[{"text":"Which isotopes exist, and which are stable?","kind":"definition"},{"text":"Which entry fits the specific isotope?","kind":"action"}]}]}]},{"id":"source","name":"Source","description":"Occurrence and production.","layers":[{"id":"occurrence","name":"Occurrence","description":"Occurrence.","findings":[{"id":"occurrence-finding","name":"Occurrence","description":"Occurrence.","questions":[{"text":"Where does cerium occur, and how is it separated from other rare earths?","kind":"provenance"},{"text":"Which entry fits rare earth mining?","kind":"action"}]}]},{"id":"supply","name":"Supply","description":"Supply.","findings":[{"id":"supply-finding","name":"Supply","description":"Supply.","questions":[{"text":"Who produces cerium, and how does its abundance affect price, with sources?","kind":"measurement"},{"text":"Which sources are cited?","kind":"provenance"}]}]}]},{"id":"use","name":"Use","description":"Uses and safety.","layers":[{"id":"uses","name":"Uses","description":"Uses.","findings":[{"id":"uses-finding","name":"Uses","description":"Uses.","questions":[{"text":"How is cerium used in catalysts, polishing, lighters, glass and pigments?","kind":"provenance"},{"text":"Which entry fits ceria?","kind":"action"}]}]},{"id":"safety","name":"Safety","description":"Safety.","findings":[{"id":"safety-finding","name":"Safety","description":"Safety.","questions":[{"text":"What hazards does cerium present, and what is known about ceria nanoparticles?","kind":"provenance"},{"text":"Is the user asking about a personal exposure, which needs a clinician or poison centre?","kind":"boundary"}]}]}]},{"id":"context","name":"Context","description":"History.","layers":[{"id":"discovery","name":"Discovery","description":"Discovery.","findings":[{"id":"discovery-finding","name":"Discovery","description":"Discovery.","questions":[{"text":"How was cerium discovered in 1803, and how was it named after the asteroid Ceres?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]},{"id":"teach","name":"Teach","description":"Teaching.","findings":[{"id":"teach-finding","name":"Teach","description":"Teaching.","questions":[{"text":"How is cerium used to teach lanthanide chemistry?","kind":"provenance"},{"text":"Which entry fits the periodic table?","kind":"action"}]}]}]}]},"agentConduct":{"may":["Describe cerium, its compounds and uses in catalysts, glass polishing and lighter flints.","Report supply sources and certification where records exist."],"mustNot":["Grind, machine or store fine cerium metal or its alloys without the fire controls they require.","Present uncertain health effects of cerium oxide nanoparticles as settled in either direction.","Dispose of rare earth processing waste into water or soil.","Hide the origin of rare earth supplies in reporting."],"requiresHuman":["Handling bulk fine cerium powder or alloys in a workplace."]},"ethics":{"considerations":["Rare earth mining and refining often leave radioactive and acid waste in the communities that host it.","Supply concentration makes cerium a matter of trade policy and pressure."],"affectedParties":["Workers handling fine metal","Communities near rare earth processing","Users of cerium products"]},"owners":{"steward":"Nobody owns the element; mine operators, refiners and holders answer for the material.","roles":[],"masterSystems":[]},"relations":[{"target":"Q105789","type":"parent","note":"registry parent class"},{"target":"Q19569","type":"parent","note":"registry parent class"},{"target":"lanthanide","type":"related","note":"in registry terms"},{"target":"heavy metal","type":"related","note":"in registry terms"},{"target":"catalytic converter","type":"related","note":"as ceria"},{"target":"lanthanum","type":"related","note":"element 57"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.cerium","Wikidata: Q1385 (https://www.wikidata.org/wiki/Q1385)","symbol: Ce","CAS: 7440-45-1"]},"properties":{"applicability":"required","items":["atomic number: 58 Z","standard atomic weight: 140.116 u","melting point: 795 degrees C","density: 6.77 g/cm3"]},"recognition":{"applicability":"required","items":["Element 58, symbol Ce","Most abundant lanthanide, with a stable tetravalent state","Lanthanum and praseodymium are the neighbouring lanthanides","A soft, silvery metal that tarnishes quickly in air, with pale yellow oxide."]},"capabilities":{"applicability":"required","items":["relay properties and isotopes","explain production and uses","relay safety information","distinguish from other lanthanides"]},"hazards":{"applicability":"required","items":["Pyrophoricity of fine metal and alloys","Supply concentration","Nanoparticle exposure questions under study"]},"interfaces":{"applicability":"required","items":["Chemical safety data sheets","Rare earth trade and export rules","Nanomaterial regulation for ceria nanoparticles"]},"context":{"applicability":"required","items":["Catalysts, glass polishing, alloys and pigments.","cerium metal and mischmetal","cerium compounds such as ceria and cerium nitrate","isotopes from cerium-119 to cerium-157, with four stable isotopes","cerium in catalysts, polishing and pigments"]}},"sources":[{"title":"Wikidata item Q1385: cerium","url":"https://www.wikidata.org/wiki/Q1385","note":"identity and sense of the item"},{"title":"Wikipedia: Cerium","url":"https://en.wikipedia.org/wiki/Cerium","note":"general description of the item"}],"openQuestions":["Should isotopes and ceria be separate entries?","How should reference data be linked?","The registry entry has merged aliases naming isotopes; should they be split off?"],"resources":{"spec":"/models/things/publications/thing-q1385/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q1385/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T22:52:19Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:26+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}