18
Ar
18
週期
3
p
個質子
電子
個中子
18
18
22
一般屬性
原子序數
18
標準原子質量
39.948
品質編號
40
類別
惰性氣體
顏色
無色
放射性
From the Greek argos, inactive
晶體結構
面居中立方
歷史
Argon was suspected to be present in air by Henry Cavendish in 1785.

It was not isolated until 1894 by Lord Rayleigh and Sir William Ramsay in Scotland.

Argon became the first member of the noble gases to be discovered.

In 1957, IUPAC agreed that the symbol should change from A to Ar.
每個外殼的電子
2, 8, 8
電子排布
[Ne] 3s2 3p6
Ar
Argon makes a distinctive blue-green gas laser
物理性質
物態
氣體
密度
0.0017837 g/cm3
熔點
83.8 K | -189.35 °C | -308.83 °F
沸點
87.3 K | -185.85 °C | -302.53 °F
熔化熱
1.18 kJ/mol
汽化熱
6.5 kJ/mol
比熱容
0.52 J/g·K
地殼豐度
0.00015%
宇宙豐度
0.02%
Vial
圖片來源: Images-of-elements
Vial of glowing ultrapure argon
CAS 編號
7440-37-1
Pubchem CID 編號
23968
原子性質
原子半徑
71 pm
共價半徑
106 pm
電負性
-
電離電位
15.7596 eV
原子體積
22.4 cm3/mol
熱導率
0.0001772 W/cm·K
氧化態
0
應用
Argon gas is used to fill conventional incandescent and fluorescent light bulbs.

Argon is also used as an inert gas shield for arc welding and cutting, as blanket for the production of titanium and other reactive elements.

It is used as a protective atmosphere for growing silicon and germanium crystals.
Argon is considered to be non-toxic
同位素
穩定同位素
36Ar, 38Ar, 40Ar
不穩定同位素
30Ar, 31Ar, 32Ar, 33Ar, 34Ar, 35Ar, 37Ar, 39Ar, 41Ar, 42Ar, 43Ar, 44Ar, 45Ar, 46Ar, 47Ar, 48Ar, 49Ar, 50Ar, 51Ar, 52Ar, 53Ar