# Sodiwm

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|

|  |
| --- |
| neon ← **sodium** → magnesium |
| Li ↑ **Na** ↓ K
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**11Na**
Y Tabl Cyfnodol |

 |

 |
| Ymddangosiad
 |
| arian golau sgleiniog   Llinellau sbectral sodiwm
 |
| Nodweddion cyffredinol
 |
| Enw, symbol, rhif
 | sodium, Na, 11
 |
| Ynganiad
 | /ˈsoʊdiəm/ SOH**-dee-əm* |
| Teulu'r elfennau
 | alkali metal
 |
| Grŵp, cyfnod, bloc
 | 1, 3, s
 |
| Rhif atomig
 | 22.98976928(2)
 |
| Patrwm yr Electronnau
 | [Ne] 3s1 |
| Electronnau / cragen
 | 2,8,1 (Image)
 |
| Nodweddion ffisegol
 |
| Stâd
 | solid
 |
| Dwysedd (oddeutu tymheredd yr ystafell)
 | 0.968 g·cm−3 |
| Dwysedd hylif / Ymdoddbwynt
 | 0.927 g·cm−3 |
| Ymdoddbwynt
 | 370.87 K, 97.72 °C, 207.9 °F
 |
| Berwbwynt
 | 1156 K, 883 °C, 1621 °F
 |
| Pwynt critigol
 | (extrapolated) 2573 K, 35 MPa
 |
| Enthalpi ymdoddiad
Gwres o ymdoddi

 | kJ·mol−1 |
| Enthalpi anweddiad
 | Cynhwysedd gwres
 | 28.230 J·mol−1·K−1 |
| Vapor pressure
 |
|

|  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| P (Pa)
 | 1
 | 10
 | 100
 | 1 k
 | 10 k
 | 100 k
 |
| at T (K)
 | 554
 | 617
 | 697
 | 802
 | 946
 | 1153
 |

 |
| Nodweddion Atomig
 |
| cyflwr ocsidiad
 | **+1**, -1 (strongly basic oxide)
 |
| Electronegativity
 | 0.93 (Graddfa Pauling)
 |
| Ionization energies (more)
 | 1af: 495.8 kJ·mol−1 |
| 2: 4562 kJ·mol−1 |
| 3ydd: 6910.3 kJ·mol−1 |
| Radiws atomig
 | 186 pm
 |
| Radiws cofalent
 | 166±9 pm
 |
| Radiws Van der Waals
 | 227 pm
 |
| Amrywiol
 |
| Strwythyr y crisal
 | body-centered cubic
 |
| Magnetic ordering
 | paramagnetic
 |
| Gwrthedd trydanol
 | (20 °C) 47.7 nΩ·m
 |
| Dargludiad Thermal
 | 142 W·m−1·K−1 |
| Ehangiad thermal
 | (25 °C) 71 µm·m−1·K−1 |
| Cyflymder sain
 | (20 °C) 3200 m·s−1 |
| Modwlws Young
 | 10 GPa
 |
| Modwlws Shear
 | 3.3 GPa
 |
| Modwlws Bulk
 | 6.3 GPa
 |
| Graddfa caledwch Mohs
 | 0.5
 |
| Brinell hardness
 | 0.69 MPa
 |
| CAS registry number
 | 7440-23-5
 |
| Most stable isotopes
 |
| Main article: Isotopes of sodium
 |
|

| iso
 | NA
 | half-life
 | DM
 | DE (MeV) | DP
Nodyn:Elementbox isotopes decay3 (2 2 1)

 |
| --- | --- | --- | --- | --- | --- |
| 23Na
 | 100%
 | 23Na is stable with 12 neutrons
 |

 |
| * v
* t
* e
 |

Elfen gemegol yn y tabl cyfnodol ydy **sodiwm** ac mae'n cael ei dynodi gan y symbol `**Na**` (o'r Lladin *natrium*) a rhif atomig 11. Mae sodiwm yn elfen gyffredin mewn cyfansoddion diwidiannol e.e. sodiwm clorid neu halen; sodiwm carbonad (i wneud gwydr); sodiwm hydrogencarbonad ('bicarbonad'); sodiwm hypoclorit (cannydd) a sodiwm hydrocsid (soda costig). Mae modd adnabod yr elfen yn y cyfansoddion trwy ei llosgi, a gwelir fflam felen.

## Yr elfen

Metel arianaidd, meddal yw sodiwm. Mae'n adweithiol iawn, felly mae'n troi'n bŵl mawn aer wrth iddo adweithio gyda'r ocsigen sydd ynddo. Cedwir y metel mewn paraffin er mwyn atal yr ocsigen gymysgu a'r anwedd dŵr sydd yn yr aer.

Os ydych yn ei gyfuno gyda dŵr, mae'n adweithio'n gyflym ac mae'r gwres yn ddigon i'w ymdoddi. Mae'n rhyddhau'r nwy hydrogen ac yn ffurfio'r alcali sodiwm hydrocsid. Os cyfyngir y sodiwm yn ystod yr adwaith, gall y gwres achosi'r nwy hydrogen cynnau a llosgi gyda fflam felen.

Ceir llawer o sodiwm yn y môr ar ffurf hydoddiant sodiwm clorid a halidau sodiwm eraill. Yn yr hydoddiant mae'r sodiwm yn bodoli ar ffurf ïonau (symbol cemegol Na+) dyfrllyd.

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