Element Rubidium
An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.
Rubidium metal shares similarities to potassium metal and caesium metal in physical appearance, softness and conductivity. Element Rubidium cannot be stored under atmospheric oxygen, as a highly exothermic reaction will ensue, sometimes even resulting in the metal catching fire.
Names and Identifiers
| Chemical Formula: | Rb |
| CAS: | 7440-17-7 |
| Molecular Weight: | 85.46780 g/mol |
| EC Number : | 231-126-6 |
| MDL Number: | MFCD00134055 |
| Color: | silvery white |
| Other Names: | Rubidij, Rubidio |
| PubChem CID: | 5357696 |
| IUPAC Name: | Rubidium |
| Inchl: | InChI=1S/Rb |
| InChI Key: | IGLNJRXAVVLDKE-UHFFFAOYSA-N |
| Canonical SMILES: | [Rb] |
| ICSC Number: | n/a |
Physical & Chemical Properties
| Phase: | Solid |
| Density: | 1.532 g/cm³ |
| Boiling Point: | 961 K (688 °C, 1270 °F) |
| Melting Point: | 312.45 K (39.30 °C, 102.74 °F) |
| Molecular Formula: | Rb |
| Flash Point: | n/a |
| Exact Mass: | 84.91180 |
| Symbol: |   |
| Signal Word: | Danger |
| Hazard Statements: | H260-H314 |
| Precautionary Statements: | P223-P231 + P232-P280-P305 + P351 + P338-P370 + P378-P422 |
| Hazard Codes: | Xi,C,F |
| Risk Phrases: | 36/37/38-36/38-34-14/15 |
| Safety Phrases: | S26-S36/37/39-S43-S45-S36 |
| RIDADR: | UN 2031 8/PG 2 |
| WGK Germany: | 3 |
| RTECS: | VL8500000 |
| Packaging Group: | III |
| Hazard Class: | 8 |
Rubidium (37Rb) has 32 isotopes, with naturally occurring rubidium being composed of just two isotopes; 85Rb (72.2%) and the radioactive 87Rb (27.8%).
Normal mixes of rubidium are radioactive enough to fog photographic film in approximately 30 to 60 days.
Naturally occurring isotopes
| Isotope | Mass/Da | Natural abundance (atom %) | Nuclear spin (I) | Magnetic moment (μ/μN) |
|---|---|---|---|---|
| 85Rb | 84.911794 (3) | 72.17 (2) | 5/2 | 1.35303 |
| 87Rb | 86.909187 (3) | 27.83 (2) | 3/2 | 2.75124 |
Radiosotope data
| Isotope | Mass/Da | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
|---|---|---|---|---|---|
| 81Rb | 80.91900 | 4.57 h | EC to 81Kr | 3/2 | 2.060 |
| 82Rb | 81.91821 | 1.258 m | EC to 82Kr | 1 | 0.554508 |
| 83Rb | 82.91511 | 86.2 d | EC to 83Kr | 5/2 | 1.425 |
| 84Rb | 83.914387 | 32.9 d | EC to 84Kr; β– to 84Sr | 2 | -1.32412 |
| 86Rb | 85.911170 | 18.65 d | EC to 86Kr; β– to 86Sr | 2 | -1.6920 |
| 87Rb | 86.9091835 | 4.75 x 1010 y | β– to 87Sr | 3/2 |