# Hydrogen

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|

|  |
| --- |
| - ← **hydrogen** → heliwm |
| - ↑ **H** ↓ Li
 |

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**1H**
Y Tabl Cyfnodol |

 |

 |
| Ymddangosiad
 |
| Nwy di-liw er fod iddo rhyw wawr ysgafn, biws pan fo'n blasma   Llinellau sbectral hydrogen
 |
| Nodweddion cyffredinol
 |
| Enw, symbol, rhif
 | hydrogen, H, 1
 |
| Teulu'r elfennau
 | anfetel
 |
| Grŵp, cyfnod, bloc
 | 1, 1, s
 |
| Rhif atomig
 | 1.00794(7)
 |
| Patrwm yr Electronnau
 | 1s1 |
| Electronnau / cragen
 | 1 (Image)
 |
| Nodweddion ffisegol
 |
| Lliw
 | di-liw
 |
| Stâd
 | nwy
 |
| Dwysedd
 | (0 °C, 101.325 kPa) 0.08988 g/L
 |
| Dwysedd hylif / Ymdoddbwynt
 | 0.07 (0.0763 solid) g·cm−3 |
| Dwysedd hylif / Ymdoddbwynt
 | 0.07099 g·cm−3 |
| Ymdoddbwynt
 | 14.01 K, -259.14 °C, -434.45 °F
 |
| Berwbwynt
 | 20.28 K, -252.87 °C, -423.17 °F
 |
| Pwynt triphlyg
 | 13.8033 K (-259°C), 7.042 kPa
 |
| Pwynt critigol
 | 32.97 K, 1.293 MPa
 |
| Enthalpi ymdoddiad
Gwres o ymdoddi

 | kJ·mol−1 |
| Enthalpi anweddiad
 | Cynhwysedd gwres
 | (H2) 28.836 J·mol−1·K−1 |
| Vapor pressure
 |
|

|  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| P (Pa)
 | 1
 | 10
 | 100
 | 1 k
 | 10 k
 | 100 k
 |
| at T (K)
 |  |  |  |  | 15
 | 20
 |

 |
| Nodweddion Atomig
 |
| cyflwr ocsidiad
 | 1, -1 (ocsid amffoterig)
 |
| Electronegativity
 | 2.20 (Graddfa Pauling)
 |
| egni ïoneiddiadau
 | 1st: 1312.0 kJ·mol−1 |
| Radiws cofalent
 | 31±5 pm
 |
| Radiws Van der Waals
 | 120 pm
 |
| Amrywiol
 |
| Strwythyr y crisal
 | hecsagonal
 |
| Magnetic ordering
 | diamagnetic
 |
| Dargludiad Thermal
 | 0.1805 W·m−1·K−1 |
| Cyflymder sain
 | (gas, 27 °C) 1310 m·s−1 |
| CAS registry number
 | 1333-74-0
 |
| Most stable isotopes
 |
| Main article: Isotopes of hydrogen
 |
|

| iso
 | NA
 | half-life
 | DM
 | DE (MeV) | DP
 |
| --- | --- | --- | --- | --- | --- |
| 1H
 | 99.985%
 | 1H is stable with 0 neutron
 |
| 2H
 | 0.015%
 | 2H is stable with 1 neutrons
 |
| 3H
 | trace
 | 12.32 y
 | β− | 0.01861
 | 3He
 |

 |
| * v
* t
* e
 |

Elfen gemegol gyda'r symbol **H** a'r rhif atomig 1 yw **hydrogen**. Yr hen enw Cymraeg amdano oedd: **ulai**, **awyr hylosg** a **gwyen**. Hydrogen yw'r elfen ysgafnaf a mwyaf cyffredin yn y tabl cyfnodol; mae 75% o fater baryonaidd wedi'i wneud ohono, ond dylid cofio, wrth gwrs, y ceir mater arall: mater tywyll. Ar dymheredd arferol y labordy, mae'n nwy di-liw, diarogl, anfetalaidd a fflamadwy iawn, ac fe'i ceir yn ffurf molecylau gyda'r fformiwla H2. Yr isotop mwyaf cyffredin ohono, fodd bynnag, yw *protiwm* (symbol 1H), sydd ag un proton a dim niwtron. Ar y Ddaear, mae i'w gael fel arfer fel moleciwlau fel dŵr, cyfansoddion organig ac organebau byw. Mae sêr yn cynnwys hydrogen gan amlaf, ond yn ffurf plasma.

Daw'r enw o'r Groeg *ὕδωρ (hudôr)* (dŵr), a *gennen* (creawdwr).

Mae gan hydrogen ran bwysig i'w chwarae mewn adweithiau asid-bâs gan fod cyfnewid protonau rhwng moleciwlau hydawdd yn rhan mor bwysig o'r adweithiau hynny. Mewn cyfansoddyn ïonig, mae hydrogen yn cymeryd gwefr negydd (h.y. anion), neu wefr bosydd (cation), a ddynodir gan y symbol H+.

## Hanes

Hydrogen Spectrum Test
Cynhyrchwyd nwy hydrogen mewn labordy am y tro cyntaf yn yr 16eg ganrif, drwy gymysgu metalau ag asid. Rhwng 1766–81 Henry Cavendish oedd y cyntaf i ddatgan fod nwy hydrogen yn sylwedd unigryw, ar wahân, a'i fod yn cynhyrchu dŵr pan fo'n llosgi, ac o hyn y tarddodd yr enw (y Crëwr Dŵr).

## Gweler hefyd

* Hen enwau Cymraeg am yr elfennau
* Bond hydrogen

## Cyfeiriadau