Argon facts for kids

Argon is a chemical element. Its symbol is Ar, and its atomic number (which is the number of protons) is 18. Argon is a special type of gas called a noble gas. This means its atoms are very stable and usually don't react with other elements. They don't easily lose or gain electrons or protons.

Argon atoms are found all around us in the air. About 1% of the Earth's atmosphere (the air we breathe) is made up of argon.

Argon is very useful in many ways. For example, it's often used when people are welding steel. It helps by pushing away the air around the weld. This stops the oxygen in the air from mixing with the hot metal, which could cause problems.

Quick facts for kids
Argon, ₁₈Ar

Argon
Pronunciation	/ˈɑːrɡɒn/ ​(AR-gon)
Appearance	colorless gas exhibiting a lilac/violet glow when placed in a high voltage electric field
Standard atomic weight Ar, std(Ar)	[39.792, 39.963] conventional: 39.948
Argon in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Ne ↑ Ar ↓ Kr chlorine ← argon → potassium
Atomic number (Z)	18
Group	group 18 (noble gases)
Period	period 3
Block	p
Electron configuration	[Ne] 3s2 3p6
Electrons per shell	2, 8, 8
Physical properties
Phase at STP	gas
Melting point	83.80 K ​(−189.35 °C, ​−308.83 °F)
Boiling point	87.30 K ​(−185.85 °C, ​−302.53 °F)
Density (at STP)	1.784 g/L
when liquid (at b.p.)	1.40 g/cm3
Triple point	83.8058 K, ​69 kPa
Critical point	150.87 K, 4.898 MPa
Heat of fusion	1.18 kJ/mol
Heat of vaporization	6.43 kJ/mol
Molar heat capacity	5R/2 = 20.786 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K)   47 53 61 71 87
Atomic properties
Oxidation states	0
Electronegativity	Pauling scale: no data
Ionization energies	(more)
Covalent radius	106±10 pm
Van der Waals radius	188 pm
Spectral lines of argon
Other properties
Natural occurrence	primordial
Crystal structure	​face-centered cubic (fcc)
Speed of sound	(gas, 27 °C) 323 m/s
Thermal conductivity	17.72x10-3  W/(m⋅K)
Magnetic ordering	diamagnetic
CAS Number	7440–37–1
History
Discovery	Lord Rayleigh and William Ramsay (1894)
First isolation	Lord Rayleigh and William Ramsay (1894)
Main isotopes of argon
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 36Ar 0.337% 36Ar is stable with 18 neutrons 37Ar syn 35 d ε 0.813 37Cl 38Ar 0.063% 38Ar is stable with 20 neutrons 39Ar trace 269 y β− 0.565 39K 40Ar 99.600% 40Ar is stable with 22 neutrons 41Ar syn 109.34 min β− 2.49 41K 42Ar syn 32.9 y β− 0.600 42K

What is Argon?

Argon is a chemical element with the symbol Ar. It has an atomic number of 18, meaning each argon atom has 18 protons in its center. It belongs to a special group of elements called noble gases.

Why is it called a Noble Gas?

Noble gases are known for being very unreactive. This means they don't easily combine with other elements to form new substances. Argon's atoms have a full outer shell of electrons, which makes them very stable. Because of this, they don't usually lose or gain electrons.

Where is Argon Found?

Argon is the third most common gas in the Earth's atmosphere. It makes up about 1% of the air we breathe. It's a colorless, odorless gas, so you can't see or smell it.

How is Argon Used?

Argon has many important uses because of its unreactive nature.

• Welding: One of its main uses is in welding. When metals are heated to very high temperatures during welding, they can react with oxygen in the air. Argon is used to create a protective shield around the weld, pushing away the air. This stops the metal from reacting with oxygen and keeps the weld strong.
• Light Bulbs: Argon is also used in incandescent light bulbs. Filling the bulb with argon helps to stop the hot wire (filament) from burning out quickly.
• Protecting Materials: Because it doesn't react, argon is used to protect sensitive materials from air and moisture. For example, some old documents or valuable artworks are stored in an argon atmosphere to preserve them.
• Glow in the Dark: When electricity passes through argon gas, it glows with a beautiful lilac or violet color. This is why it's used in some types of neon lamps and plasma balls.

Who Discovered Argon?

Argon was discovered in 1894 by two scientists: Lord Rayleigh and William Ramsay. They found it while studying air and noticed there was a small amount of gas that didn't react with anything. They named it "argon," which comes from a Greek word meaning "lazy" or "inactive," because of its unreactive nature.

Related pages

• List of common elements
• Periodic table

Images for kids

• 

  A small piece of rapidly melting solid argon

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  A: test-tube, B: dilute alkali, C: U-shaped glass tube, D: platinum electrode

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  Captioned "Argon", caricature of Lord Rayleigh in Vanity Fair, 1899

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  Space-filling model of argon fluorohydride

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  Cylinders containing argon gas for use in extinguishing fire without damaging server equipment

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  A sample of caesium is packed under argon to avoid reactions with air

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  Gloveboxes are often filled with argon, which recirculates over scrubbers to maintain an oxygen-, nitrogen-, and moisture-free atmosphere

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  Argon gas-discharge lamp forming the symbol for argon "Ar"

See also

In Spanish: Argón para niños