Actinium (Ac)
Actinium (Ac, element 89) is an actinide in group 3, period 7. Atomic mass 227, electron configuration [Rn] 6d¹ 7s², uses and facts.
About Actinium
Actinium is an actinide with the symbol Ac and atomic number 89. It is a solid at room temperature, and it sits in group 3, period 7 of the periodic table. Actinium was discovered in 1899 by André-Louis Debierne.
Actinium key facts
- Atomic number: 89
- Symbol: Ac
- Atomic mass: 227 u
- Category: actinide
- Group: 3
- Period: 7
- State at room temperature: solid
- Electron configuration: [Rn] 6d¹ 7s²
- Electronegativity (Pauling): 1.1
- Melting point: 1500 K (1226.85 °C)
- Boiling point: 3500 K (3226.85 °C)
- Density: 10.07 g/cm³
- Common oxidation states: +2, +3
Electron configuration
The electron configuration of actinium is [Rn] 6d¹ 7s². The part in brackets is the noble gas core; the rest shows how the outer electrons fill their subshells.
Uses of actinium
- Cancer treatment
- Neutron source
- Research
Did you know?
Actinium glows blue in the dark due to its radioactivity ionizing the surrounding air.
Other elements in group 3 and neighbours
Frequently asked questions
What is the atomic number of actinium?
The atomic number of actinium is 89, which means every actinium atom has 89 protons.
What is the electron configuration of actinium?
The electron configuration of actinium is [Rn] 6d¹ 7s².
What group and period is actinium in?
Actinium is an actinide in group 3, period 7.
What state is actinium at room temperature?
Actinium is a solid at room temperature.
What is actinium used for?
Actinium is used for cancer treatment, neutron source, research.