Radium (Ra) – element 88
Radium is a chemical element with the symbol Ra and atomic number 88. It is a alkaline earth metal in group 2 (alkaline earth metals), period 7 of the periodic table (s-block), and is a solid at room temperature.
Radium (Ra) has atomic number 88, atomic mass [226] and electron configuration [Rn] 7s2.
Radium facts
| Symbol | Ra |
|---|---|
| Atomic number | 88 |
| Atomic mass | [226] |
| Category | alkaline earth metal |
| Group | group 2 (alkaline earth metals) |
| Period | 7 |
| Block | s-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 |
| Noble-gas notation | [Rn] 7s2 |
| Electrons per shell | 2, 8, 18, 32, 18, 8, 2 |
| Valence electrons | 2 |
Bohr model and shells
Radium has 88 electrons in 7 shells: 2, 8, 18, 32, 18, 8, 2. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 1233 K (959.9 °C) |
|---|---|
| Boiling point | 2010 K (1736.8 °C) |
| Density | 5.5 g/cm³ |
| Electronegativity (Pauling) | 0.9 |
| Electron affinity | 9.6485 kJ/mol |
| Ionization energies | 509.3, 979 kJ/mol (1st, 2nd) |
| Discovered by | Pierre Curie |
Use the atomic mass in the molar mass calculator for any formula containing Ra.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of radium?
The atomic mass of radium is [226] (mass number of its longest-lived isotope, since it has no stable isotope).
What is the electron configuration of radium?
Radium has 88 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s², or [Rn] 7s² in noble-gas notation. Electrons per shell: 2, 8, 18, 32, 18, 8, 2.
How many valence electrons does radium have?
Radium has 2 valence electrons (group 2).
Is radium a metal?
Yes. Radium is a alkaline earth metal.
Where is radium on the periodic table?
Radium is in group 2 (alkaline earth metals), period 7, in the s-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.