Ion | Colour | Stability | Preparation |
Md2+ | | easy to oxidize, but stable to water | Zn or Cr2+ on Md3+ |
No2+ | | stable | normal oxdn state in acid |
| | | |
Ac3+ | colourless | stable | normal oxdn state in acid |
U3+ | claret | evolves H2 on standing; easily oxidized by air | Na or Zn/Hg on UO22+ |
Np3+ | blue-purple | stable to water; easily oxidized by air | Zn/Hg or H2(Pt) reduction |
Pu3+ | blue-violet | stable to water & air; readily oxidized | SO2 or NH2OH reduction |
Am3+ | pink | stable; difficult to oxidize | I, SO2 , etc... on higher states |
Cm3+ | pale yellow | stable; chemical oxidation not possible | normal oxdn state in acid |
Bk3+ | green | stable; can be oxidized to Bk4+ | normal oxdn state in acid |
Cf3+ | green | stable | normal oxdn state in acid |
Es3+ | | stable | normal oxdn state in acid |
Fm3+ | | stable | normal oxdn state in acid |
Md3+ | | stable, but easily reduced to Md2+ | normal oxdn state in acid |
No3+ | | easily reduced to No2+ | CeIV or BrO3 on No2+ |
Lr3+ | | stable | normal oxdn state in acid |
| | | |
Th4+ | colourless | stable | normal oxdn state in acid |
Pa4+ | colourless | stable to water; easily oxidized | Zn/Hg on PaV(aq) |
U4+ | green | stable to water; easily oxidized by air to UO22+ | Zn/Hg on UO22+ |
Np4+ | yellow-green | stable to water; slowly oxidized by air to NpO2+ | SO2 on NpO2+ in H2SO4 |
Pu4+ | tan-brown | stable in 6M acid, disproportionates at higher pH | SO2 or NO2 on PuO22+ |
Am4+ | pink? | only stable as fluoride complex; easily reduced | Am(OH)4 in 15 M NH4F |
Cm4+ | pale yellow | only as fluoride complex; stable only 1 hr at 25°C | CmF4 in 15 M CsF |
Bk4+ | yellow | marginally stable; easily reduced | |
| | | |
Pa5+ | colourless | stable; readily hydrolyzed | normal oxdn state in acid |
UO2+ | | unstable to disproportionation (least at pH 2-4) | a transient species |
NpO2+ | green | stable; disproportionates at high acidity | hot HNO3 on Np4+ |
PuO2+ | pink-purple | tends to disproportionate (least at low pH) | NH2OH on PuO22+ |
AmO2+ | yellow | disproportionates in acid; reduced by its a-decay | ClO or cold S2O82-on Am3+ |
| | | |
UO22+ | yellow | stable; difficult to reduce | oxidation by air in HNO3 |
NpO22+ | pink-red | stable; easy to reduce | oxidation by CeIV, MnO4, BrO3 , etc. |
PuO22+ | orange-pink | stable; easy to reduce; reduced by its a -decay | oxidation by CeIV, MnO4, BrO3 , etc. |
AmO22+ | rum-brown | easy to reduce; rapidly reduced by its a -decay | oxidation by CeIV, MnO4, BrO3 , etc. |
| | | |
NpO53- | deep green | only in alkaline solution | O3 or S2O82- on NpO22+ + alkali |
PuO53- | deep green | only in alkaline solution; oxidizes water | O3 or S2O82- on PuO22+ + alkali |