The Lanthanoid series element known for exhibiting a +4 oxidation state is Cerium. The electronic configuration of Cerium ( Ce ) is: Ce:[Xe]4f15d16s2 When Cerium is in the +4 oxidation state (Ce+4), it has the electronic configuration: Ce+4:[Xe]4f05d06s0 In this state, Cerium has a stable noble gas configuration, which is why it is well-known to exhibit a +4 oxidation state.