monoatomic tetracation uranium(4+) 238.02890 238.051 CAS:16089-60-4 CHEBI:32995 Gmelin:7614 HNVACBPOIKOMQP-UHFFFAOYSA-N InChI=1S/U/q+4 U U(4+) [U+4] chebi_ontology uranium(4+) uranium(4+) ion uranium(IV) cation uranium cation