89Ac227
Actinium
Actinide · element 89 · f-block (shown below the main table)
Quick facts
| Symbol | Ac |
|---|---|
| Atomic number | 89 |
| Relative atomic mass | 227 |
| Category | Actinide |
| Position | f-block (shown below the main table) |
| State at 20 °C | Solid |
| Melting point | 1,050 °C |
| Boiling point | 3,198 °C |
| Density | 10.07 g/cm³ |
| Electronegativity | 1.1 |
| Electron configuration | [Rn] 6d1 7s2 |
About Actinium
Actinium has the symbol Ac and atomic number 89, which means every actinium atom has 89 protons in its nucleus and, in a neutral atom, 89 electrons. At room temperature it is a solid.
Actinides are the second row of the f-block. They are all radioactive, and only a few (like uranium and thorium) occur naturally in large amounts.
It melts at 1,050 °C and boils at 3,198 °C.
Explore it
See where actinium sits, and drag the temperature slider to watch it melt and boil, on the interactive periodic table. Practise with quizzes on OmniEx.