# Potasiwm

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| --- |
| argon ← **potasiwm** → calcium |
| Na ↑ **K** ↓ Rb
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**19K**
Y Tabl Cyfnodol |

 |

 |
| Ymddangosiad
 |
| arian golau   Perlau o botasiwm dan olew paraffin. Maint y berl fwyaf ydy 0.5 cm. Isod: Llinellau sbectral potasiwm.
 |
| Nodweddion cyffredinol
 |
| Enw, symbol, rhif
 | potasiwm, K, 19
 |
| Ynganiad
 | /p**[invalid input: 'ɵ']**ˈtæsiəm/ *po-**TAS**-ee-əm* |
| Teulu'r elfennau
 | alkali metal
 |
| Grŵp, cyfnod, bloc
 | 1, 4, s
 |
| Rhif atomig
 | 39.0983(1)
 |
| Patrwm yr Electronnau
 | [Ar] 4s1 |
| Electronnau / cragen
 | 2, 8, 8, 1 (Image)
 |
| Nodweddion ffisegol
 |
| Stâd
 | solid
 |
| Dwysedd (oddeutu tymheredd yr ystafell)
 | 0.862 g·cm−3 |
| Dwysedd hylif / Ymdoddbwynt
 | 0.828 g·cm−3 |
| Ymdoddbwynt
 | 336.53 K, 63.38 °C, 146.08 °F
 |
| Berwbwynt
 | 1032 K, 759 °C, 1398 °F
 |
| Pwynt triphlyg
 | 336.35 K (63°C),  kPa
 |
| Enthalpi ymdoddiad
Gwres o ymdoddi

 | kJ·mol−1 |
| Enthalpi anweddiad
 | Cynhwysedd gwres
 | 29.6 J·mol−1·K−1 |
| Nodweddion Atomig
 |
| cyflwr ocsidiad
 | 1 (strongly basic oxide)
 |
| Electronegativity
 | 0.82 (Graddfa Pauling)
 |
| Ionization energies (more)
 | 1af: 418.8 kJ·mol−1 |
| 2: 3052 kJ·mol−1 |
| 3ydd: 4420 kJ·mol−1 |
| Radiws atomig
 | 227 pm
 |
| Radiws cofalent
 | 203±12 pm
 |
| Radiws Van der Waals
 | 275 pm
 |
| Amrywiol
 |
| Strwythyr y crisal
 | body-centered cubic
 |
| Magnetic ordering
 | paramagnetig
 |
| Gwrthedd trydanol
 | (20 °C) 72 nΩ·m
 |
| Dargludiad Thermal
 | 102.5 W·m−1·K−1 |
| Ehangiad thermal
 | (25 °C) 83.3 µm·m−1·K−1 |
| Cyflymder sain
 | (20 °C) 2000 m·s−1 |
| Modwlws Young
 | 3.53 GPa
 |
| Modwlws Shear
 | 1.3 GPa
 |
| Modwlws Bulk
 | 3.1 GPa
 |
| Graddfa caledwch Mohs
 | 0.4
 |
| Brinell hardness
 | 0.363 MPa
 |
| CAS registry number
 | 7440-09-7
 |
| Most stable isotopes
 |
| Main article: Isotopes of potasiwm
 |
|

| iso
 | NA
 | half-life
 | DM
 | DE (MeV) | DP
 |
| --- | --- | --- | --- | --- | --- |
| 39K
 | 93.26%
 | 39K is stable with 20 neutrons
Nodyn:Elementbox isotopes decay3

 |
| 41K
 | 6.73%
 | 41K is stable with 22 neutrons
 |

 |
| * v
* t
* e
 |

Elfen gemegol yw **potasiwm** gyda'r rhif atomig 19 a'r symbol `K`. Mae'n rhan o 'r metelau alcalïaidd yn y tabl cyfnodol. Metel feddal iawn yw potasiwm 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 botasiwm ocsid ffurfio dros ei wyneb yn ystod adwaith gydag ocsigen o'r aer. Er mwyn atal yr adwaith caiff potasiwm ei storio o dan olew paraffîn sy'n cadw'r aer i ffwrdd.

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