# Rwbidiwm

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|

|  |
| --- |
| krypton ← **rwbidiwm** → strontium |
| K ↑ **Rb** ↓ Cs
 |

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**37Rb**
Y Tabl Cyfnodol |

 |

 |
| Ymddangosiad
 |
| llwydwyn  |
| Nodweddion cyffredinol
 |
| Enw, symbol, rhif
 | rwbidiwm, Rb, 37
 |
| Ynganiad
 | /r**[invalid input: 'ʉ']**ˈbɪdiəm/ *roo-**BID**-ee-əm* |
| Teulu'r elfennau
 | alkali metal
 |
| Grŵp, cyfnod, bloc
 | 1, 5, s
 |
| Rhif atomig
 | 85.4678(3)
 |
| Patrwm yr Electronnau
 | [Kr] 5s1 |
| Electronnau / cragen
 | 2, 8, 18, 8, 1 (Image)
 |
| Nodweddion ffisegol
 |
| Stâd
 | solid
 |
| Dwysedd (oddeutu tymheredd yr ystafell)
 | 1.532 g·cm−3 |
| Dwysedd hylif / Ymdoddbwynt
 | 1.46 g·cm−3 |
| Ymdoddbwynt
 | 312.46 K, 39.31 °C, 102.76 °F
 |
| Berwbwynt
 | 961 K, 688 °C, 1270 °F
 |
| Pwynt critigol
 | (extrapolated) 2093 K, 16 MPa
 |
| Enthalpi ymdoddiad
Gwres o ymdoddi

 | kJ·mol−1 |
| Enthalpi anweddiad
 | Cynhwysedd gwres
 | 31.060 J·mol−1·K−1 |
| Vapor pressure
 |
|

|  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| P (Pa)
 | 1
 | 10
 | 100
 | 1 k
 | 10 k
 | 100 k
 |
| at T (K)
 | 434
 | 486
 | 552
 | 641
 | 769
 | 958
 |

 |
| Nodweddion Atomig
 |
| cyflwr ocsidiad
 | 1 (strongly basic oxide)
 |
| Electronegativity
 | 0.82 (Graddfa Pauling)
 |
| Ionization energies
 | 1st: 403 kJ·mol−1 |
| 2: 2632.1 kJ·mol−1 |
| 3ydd: 3859.4 kJ·mol−1 |
| Radiws atomig
 | 248 pm
 |
| Radiws cofalent
 | 220±9 pm
 |
| Radiws Van der Waals
 | 303 pm
 |
| Amrywiol
 |
| Strwythyr y crisal
 | body-centered cubic
 |
| Magnetic ordering
 | paramagnetic
 |
| Gwrthedd trydanol
 | (20 °C) 128 nΩ·m
 |
| Dargludiad Thermal
 | 58.2 W·m−1·K−1 |
| Cyflymder sain
 | (20 °C) 1300 m·s−1 |
| Modwlws Young
 | 2.4 GPa
 |
| Modwlws Bulk
 | 2.5 GPa
 |
| Graddfa caledwch Mohs
 | 0.3
 |
| Brinell hardness
 | 0.216 MPa
 |
| CAS registry number
 | 7440-17-7
 |
| Most stable isotopes
 |
| Main article: Isotopes of rwbidiwm
 |
|

| iso
 | NA
 | half-life
 | DM
 | DE (MeV) | DP
Nodyn:Elementbox isotopes decay2
Nodyn:Elementbox isotopes decay4

 |
| --- | --- | --- | --- | --- | --- |
| 85Rb
 | 72.168%
 | 85Rb is stable with 48 neutrons
Nodyn:Elementbox isotopes decay2

 |
| 87Rb
 | 27.835%
 | 4.88 × 1010 y
 | β− | 0.283
 | 87Sr
 |

 |
| * v
* t
* e
 |

Elfen gemegol yw **rwbidiwm** gyda'r rhif atomig 37 a'r symbol **Rb**. Mae'n rhan o'r metelau alcalïaidd yn y tabl cyfnodol. Metel feddal iawn yw rwbidiwm a gellir ei dorri gyda chyllell yn hawdd. Mae'r metel yn adweithiol iawn felly mae'r wyneb newydd yn sgleiniog, ond mae'n troi'n bŵl yn gyflym wrth i haen o rwbidiwm ocsid ffurfio dros ei wyneb yn ystod adwaith gydag ocsigen o'r aer. Er mwyn atal yr adwaith caiff y metel ei storio o dan olew paraffin sy'n cadw'r aer i ffwrdd.

## Cyfeiriadau

 *Eginyn erthygl sydd uchod am **gemeg**. Gallwch helpu Wicipedia drwy ychwanegu ato.*

Wiciadur
Chwiliwch am rwbidiwm
yn Wiciadur.