Noble gases are the least reactive of all elements. That’s because they have eight valence electrons, which fill their outer energy level. The octet rule states that atoms react to form compounds that allow them to have eight valence electrons like the noble gases, which are the least reactive elements.

Neon, like all noble gases, has a full valence shell. Noble gases have eight electrons in their outermost shell, except in the case of helium, which has two….Electron configuration.

All the noble gases, except for helium, have 8 valence electrons. Helium has 2 valence electrons. The valence electrons participate in chemical bonding processes and are present in the outermost shell.

The noble gases, in order of their density, are helium, neon, argon, krypton, xenon and radon. They are called noble gases because they are so majestic that, in general, they don’t react with anything. For this reason they are also known as inert gases.

Argon is often used when an inert atmosphere is needed. It is used in this way for the production of titanium and other reactive elements. It is also used by welders to protect the weld area and in incandescent light bulbs to stop oxygen from corroding the filament.

Argon is nontoxic and largely inert. It can act as a simple asphyxiant by displacing the oxygen in air to levels below that required to support life. Inhalation of argon in excessive amounts can cause dizziness, nausea, vomiting, loss of consciousness, and death.

Gases used in welding and cutting processes include: shielding gases such as carbon dioxide, argon, helium, etc. fuel gases such as acetylene, propane, butane, etc. oxygen, used with fuel gases and also in small amounts in some shielding gas mixtures.

The normal gas for TIG welding is argon (Ar). Helium (He) can be added to increase penetration and fluidity of the weld pool. Argon or argon/helium mixtures can be used for welding all grades. In some cases, nitrogen (N2) and/or hydrogen (H2) can be added to achieve special properties.

Carbon Dioxide (CO2) It is the only one that can be used in its pure form without the addition of an inert gas. Pure CO2 provides very deep weld penetration, which is useful for welding thick material. However, it also produces a less stable arc and more spatter than when it is mixed with other gases.

Argon

Stainless steel can be welded with shielded metal arc welding (MIG), gas tungsten arc welding (TIG) and stick welding, and each of these processes will yield a slightly different result.

pure Argon

The gray is caused because the metal is too hot after the shielding gas is removed from it and the weld has absorbed impurities from the atmosphere.

Carbon dioxide (CO2) is actually an active gas. So, in short, TIG welding needs pure argon to protect the tungsten electrode, and MIG welding works best on a 75%/25% argon/carbon dioxide mix to get good weld penetration and flow.

Use a pure tungsten or zirconiated tungsten electrode when AC welding aluminum. Don’t use a 2 percent thoriated tungsten electrode. Make sure you use a tungsten electrode large enough in diameter to carry the welding current you plan to use. Remember that AC welding requires larger–diameter tungsten electrodes.