Element 88 · Alkaline earth metal
Radium (Ra) — Element 88
Latin radius — ray
Radium (Ra) is an alkaline earth metal in Period 7, Group 2 of the periodic table with atomic number 88, standard atomic weight [226] u, and ground-state electron configuration [Rn] 7s². At standard temperature and pressure it is classified as a solid with 2 valence electrons and common oxidation states +2.
Historical luminous paints; research
What are the atomic properties and physical constants of Radium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 88
- Standard atomic mass
- [226] u
- Chemical family
- Alkaline earth metal
- Ground-state configuration
- [Rn] 7s²
- Electrons per shell
- 2, 8, 18, 32, 18, 8, 2
- Valence electrons
- 2
- Common ion charges / oxidation states
- +2
- Phase at STP
- Solid
- Pauling electronegativity
- 0.90 Pauling
- First ionization energy
- 509 kJ/mol
- Atomic radius
- —
- Melting point
- 700 °C
- Boiling point
- 1,737 °C
- Discovery year
- 1898
- Table coordinate
- Period 7, Group 2
- Radioactivity
- Radioactive (no stable isotopes)
How are electrons arranged across Radium’s shells?
A neutral Radium atom contains 88 electrons distributed across 7 occupied principal energy shells ([Rn] 7s²). The table below compares Radium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Ra | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 32 e⁻ | 32 e⁻ |
| n = 5 | O | 18 e⁻ | 50 e⁻ |
| n = 6 | P | 8 e⁻ | 72 e⁻ |
| n = 7 | Q | 2 e⁻ | 98 e⁻ |
Frequently Asked Questions about Radium (Ra)
What is the atomic mass and atomic number of Radium (Ra)?
Radium (Ra) has atomic number Z = 88 (88 protons in its nucleus) and an IUPAC standard atomic weight of [226] u. It sits in Period 7, Group 2 and is classified as an alkaline earth metal.
What is the ground-state electron configuration of Radium?
The neutral ground-state electron configuration of Radium (Z = 88) is [Rn] 7s². Across its 7 occupied principal shells (n = 1 to n = 7), the electrons per shell are 2, 8, 18, 32, 18, 8, 2, with 2 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Radium?
Radium commonly forms +2 oxidation states or ion charges in compounds. Its Pauling electronegativity is 0.90 and its first ionization energy is 509 kJ/mol.
When was Radium discovered and what is it used for?
Radium was discovered in 1898 (Latin radius — ray). Historical luminous paints; research
How does Radium compare to neighboring elements?
Other alkaline earth metal elements: