Rikunarita-ORG/Wikinium huggingface dataset:
# Cesiwm

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Cesiwm

|  |  |  |
| --- | --- | --- |
|  |  |  |
|  |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

 |
|

|  |
| --- |
|  |
| Cesiwm mewn cynhwysydd |

 |
|  |
| Symbol | Cs |
|  Rhif | 55 |
| Dwysedd | 1.93  g·cm−3 |

Elfen gemegol yw **cesiwm** gyda'r rhif atomig 55 a'r symbol Cs. Mae'n rhan o 'r metelau alcalïaidd yn y tabl cyfnodol.

Metel feddal iawn yw cesiwm a gellir ei dorri gyda chyllell yn hawdd. Er ei fod yn solid, mae ymdoddbwynt y metel yn isel iawn (28.4 °C), ac mae'n ymdoddi'n 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 cesiwm 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. Mae'r elfen yn ffrwydro pan gyffyrdda â dŵr gan ei fod mor adweithiol. Mae cyfansoddion cesiwm yn wenwynig gan bod catïon Cs+ yn medru cyfnewid gyda chatïonau potasiwm mewn systemau biolegol.

Defnyddir cesiwn mewn clociau cesiwm i fesur amser yn wyddonol.

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

Wiciadur
Chwiliwch am cesiwm
yn Wiciadur.