Introduction to Argon
The element argon is colorless, odorless, nonflammable, and nontoxic. It is the most common noble gas and is chemically inert. There are no stable argon compounds. It is commonly used for industrial purposes, in scientific research, and as a preservative.
Ten Interesting & Fun Facts About Argon
- Argon is twice as abundant as water vapor and over 20 times as abundant as carbon dioxide.
- The word argon is derived from a Greek word meaning “lazy” and “inactive.”
- The American National Archives preserve the Declaration of Independence and the Constitution with argon. They used to be preserved by helium, however, it was replaced because it would leak from the case and require replacement.
- Blue neon lights actually contain argon. Neon creates an orange and red glow.
- Argon is being researched as a cheaper alternative to xenon in the treatment of brain injuries. Here is a new study on the effects of inhaled argon on brain injuries in mice.
- Argon was the first noble gas to be discovered.
- The atmospheres of Mars and Mercury contain argon.
- Scientific research uses argon to search for dark matter.
- Argon glows a violet and lilac color in a gas discharge tube.
- It is as soluble as oxygen in water.
Argon in the Periodic Table
Argon, atomic symbol Ar, has an atomic number of 18, and lies in group 18, on the periodic table, below neon and to the right of chlorine. This element is the third most abundant gas in Earth’s atmosphere. Argon is a noble gas with a full valence electron shell, making it unreactive.
Argon has an electronegativity of 0 (Pauling Scale). Argon’s electron configuration is [Ne] 3s2 3p6. Other noble gasses include helium, neon, krypton, xenon, and radon. Argon shares similar properties with its group.
Argon Applications in Today’s World
What is Argon Used For?
Argon is 38% denser than air and displaces oxygen near the ground. This makes it useful to asphyxiate birds as a more humane form of slaughter. It can also act as a preservative as it replaces oxygen within a bird.
Argon can be dangerous to humans in closed areas. It is difficult to detect and creates concern for argon tank leakage into confined spaces. A man died in 1984 from asphyxiation due to argon at the construction site of an oil pipe in Alaska.
Argon can extend the shelf life of food by displacing oxygen and preventing aerial oxidation and hydrolysis. It can also preserve pharmaceuticals. Argon is also a useful barrier between oxygen and wine in winemaking.
The element argon preserves filaments in incandescent lights at high temperatures. It also stops oxygen from corroding the filaments. Low energy lightbulbs use argon and mercury. An electric discharge passes through the gas to generate UV light that activates a coating on the inside surface of the bulb.
- Graphite Electron Furnaces to prevent graphite from burning
- Arc welding, gas metal arc welding, gas tungsten arc welding
- Processing of reactive elements such as titanium
- Growing silicon and germanium crystals
- Extinguishing fires
- Lab equipment such as gas chromatography, electrospray ionization mass spectrometry, ICP spectroscopy, and scanning electron microscopy.
- Propellant in aerosol cans
- Destroy cancer cells in cryosurgery
- Blue lasers used to weld arteries, destroy tumors, and in eye surgeries
- Thermal insulation in windows
- Inflating dry scuba suits
- Geiger counters
Where is Argon Found?
40Ar is the most common isotope of Argon on Earth. 40K decays with a half-life of 1.25 x 109 into 40Ar by electron capture and positron emission. This decay is helpful in K-Ar dating of rocks. Additionally, stellar nucleosynthesis in supernovae produces the most common argon isotope in the universe: 36Ar.
When and How Was Argon Discovered?
Henry Cavendish was the first to suspect an unreactive component of air in 1785. It wasn’t until 1894 that Lord Rayleigh and Sir William Ramsay at University College London isolated argon from a sample of air. They discovered that nitrogen produced from reactions was 0.5% lighter than atmospheric nitrogen. This gained their attention and led to the discovery of argon. Ramsay earned the 1904 Nobel Prize in Chemistry for the discovery of argon. Both H.F. Newall and W.N. Hartley also discovered argon in 1882 as new lines in air’s emission spectrum. Argon’s symbol changed from “A” to “Ar” in 1957.
Argon Chemistry – Compounds, Reactions, Oxidation States, Isolation
Chemical Properties of Argon Element
Argon is chemically inert due to its full valence electron shell. This makes argon suitable for storage and as a preservative.
Argon has a full octet of electrons making it very stable and resistant to bonding with other elements. Noble gasses were thought to be unable to form compounds until 1962. Scientists synthesized the first argon compound in 1975 with tungsten pentacarbonyl. The University of Helsinki discovered argon fluorohydride in 2000. As a result, weak argon compounds gained official recognition. Adding ultraviolet light onto frozen argon, hydrogen fluoride, and caesium iodide creates argon fluorohydride.
Isolation of Argon
Fractionally distilling liquid air in a cryogenic air separation unit separates liquid nitrogen and oxygen from argon by their boiling points. Over half a million tons of argon are produced as a result.
Argon Oxidation States
Since argon is a noble gas, it has no oxidation states.
Physical Properties of Element Argon
The element argon is denser than oxygen as an odorless and colorless gas. It is white as a solid. It is soluble in water and nonflammable. Argon is desirable for industrial purposes because of its electronic properties and low thermal conductivity.
- Symbol: Ar
- Melting point: -189.34°C
- Boiling point: -185.848°C
- Density (g cm−3): 1.784
- Atomic mass: 39.948
- Atomic number: 18
- Electronegativity (Pauling Scale): 0
- Classification: Noble Gas, Group 18
- Crustal abundance (ppm): 1.2
- Electron configuration: [Ne] 3s2 3p6
- Key Isotopes: 36Ar, 38Ar, 39Ar, 40Ar
- Toxicity: Non-toxic
Where Can I Buy Elemental Argon?
Argon is the cheapest noble gas due to its abundance. A small sample of argon gas costs around $11.