Dubnium
Hypothesized research says that dubnium is a member of group 5 in the 6d series of transition metals, placing it under vanadium, niobium, and tantalum. Dubnium should share most properties, such as its valence electron configuration and having a mainly +5 oxidation state, with the other group 5 elements, with a few exceptions due to relativistic effects. Limited research of dubnium chemistry has confirmed this. Solution chemistry experiments have shown that dubnium often behaves more like niobium rather than tantalum, breaking periodic trends.