Actinides are typical metals.
All of them are soft and have a silvery color (but tarnish in air), relatively high density and plasticity.
Some of them can be cut with a knife.
Their electrical resistivity varies between 15 and 150 µOhm·cm.
The hardness of thorium is similar to that of soft steel, so heated pure thorium can be rolled in sheets and pulled into wire.
Thorium is nearly half as dense as uranium and plutonium, but is harder than either of them.
All actinides are radioactive, paramagnetic, and, with the exception of actinium, have several crystalline phases: plutonium has seven, and uranium, neptunium and californium three.
The crystal structures of protactinium, uranium, neptunium and plutonium do not have clear analogs among the lanthanides and are more similar to those of the 3d-transition metals.

All actinides are pyrophoric, especially when finely divided, that is, they spontaneously ignite upon reaction with air at or below 55 °C (130 °F).
The melting point of actinides does not have a clear dependence on the number of f-electrons.
The unusually low melting point of neptunium and plutonium (~640 °C) is explained by hybridization of 5f and 6d orbitals and the formation of directional bonds in these metals.
Actinides are typical metals. All of them are soft and have a silvery color (but tarnish in air), relatively high density and plasticity. Some of them can be cut with a knife. Their electrical resistivity varies between 15 and 150 µOhm·cm. The hardness of thorium is similar to that of soft steel, so heated pure thorium can be rolled in sheets and pulled into wire. Thorium is nearly half as dense as uranium and plutonium, but is harder than either of them. All actinides are radioactive, paramagnetic, and, with the exception of actinium, have several crystalline phases: plutonium has seven, and uranium, neptunium and californium three. The crystal structures of protactinium, uranium, neptunium and plutonium do not have clear analogs among the lanthanides and are more similar to those of the 3d-transition metals.
All actinides are pyrophoric, especially when finely divided, that is, they spontaneously ignite upon reaction with air at or below 55 °C (130 °F). The melting point of actinides does not have a clear dependence on the number of f-electrons. The unusually low melting point of neptunium and plutonium (~640 °C) is explained by hybridization of 5f and 6d orbitals and the formation of directional bonds in these metals.
Actinide