Tag Archives: element faqs

Vanadium Facts

Vanadium is the 23rd element of the periodic table. These vanadium facts contain chemical and physical data along with general information and history.

Element cell for Vanadium

Vanadium Periodic Table Cell

Basic Vanadium Facts

Name: Vanadium

Atomic Number: 23

Element Symbol: V

Group: 5

Period: 4

Block: d

Element Family: Transition Metal

Atomic Mass: 50.9415(1)

Electron Configuration: [Ar]3d34s2
Full: 1s22s22p63s23p63d34s(full)

Discovery: Andres Manuel del Rio in 1801

Del Rio was a mineralogy professor at the Royal School of Mines in Mexico City when he discovered what he believed to be a new element in a lead containing ore. His original name for his discovery was panchromium because of the variety of colors the salts produced. He renamed the element to erythronium (Latin for red flower) since most of these salts turned red on heating. Del Rio shipped his samples to Paris for confirmation.

In 1805, French chemist Hippolyte-Victor Collet-Sescotils published his findings about Del Rio’s lead ore. He said Del Rio’s element was just impure chromium, not a new element. Del Rio accepted this analysis and withdrew his claim.

In 1830, Swedish chemist Nils Gabriel Sefström discovered a new element he named vanadium. German chemist Friedrich Wöhler showed Sefström’s vanadium was the same as Del Rio’s discovery.

Name Origin: Vanadium is named after Vanadis, the Norse name of the Scandinavian goddess of beauty, Freyja.

Isotopes:

Natural scandium is comprised of one stable isotopes 51V and one nearly stable isotope, 50V. Twenty four artificial isotopes have been discovered ranging from 40 to 65.

50V
Vanadium-50 is a radioactive isotope containing 25 neutrons. Vanadium-50 decays 83% of the time into titanium-50 by β+ decay and 17% into chromium-50 by β decay with a half-life of 1.44×1017 years. 0.25% of natural vanadium is vanadium-50.

51V
Vanadium-51 is the only stable isotope of vanadium and contains 26 neutrons. 99.75% of natural vanadium is vanadium-51.


Vanadium

Polished vanadium disk. Credit: Heinrich Pniok (http://pse-mendelejew.de/en)

Physical Data

Density:  6.0  g/cm3

Melting Point: 2183 K ​(1910 °C, ​3470 °F)

Boiling Point: 3680 K ​(3407 °C, ​6165 °F)

State at 20ºC: Solid

Heat of Fusion: 21.5 kJ/mol

Heat of Vaporization: 444 kJ/mol

Molar Heat Capacity: 24.89 J/mol·K


Vanadium atom

Electron shell configuration for vanadium.

Atomic Data

Atomic Radius: 1.34 Å (empirical)

Covalent Radius: 1.53 Å

Van der Waals Radius:  2.07 Å

Electron Affinity: 50.655 kJ/mol

Electronegativity: 1.63

1st Ionization Energy: 650.908 kJ/mol

2nd Ionization Energy: 1410.423 kJ/mol

3rd Ionization Energy: 2828.082 kJ/mol

4th Ionization Energy: 4506.734 kJ/mol

5th Ionization Energy: 6298.727 kJ/mol

6th Ionization Energy: 12362.67 kJ/mol

7th Ionization Energy: 14530.7 kJ/mol

8th Ionization Energy: 16730.6 kJ/mol

Oxidation States: +5, +4, +3, +2  (common) +1, 0, -1 (uncommon)


Vanadium Oxidation States

Aqueous solutions of +2, +3, +4 and +5 ions of vanadium.

Fun Vanadium Facts

  • Vanadium is a medium hard, ductile, shiny, strong blue-gray metal at room temperature.
  • Vanadium was originally named panchromium because of the many different colors produced by the ions of different oxidation states. The photo shows the colors of the +2, +3, +4 and +5 oxidation states.
  • Pure vanadium was not produced until 1869 when English chemist, Henry Roscoe showed previous samples of vanadium were actually vanadium nitride (VN).
  • Most vanadium is used to strengthen steel. Vanadium-steel alloys are used in engine parts, armor plating, axles and tools.
  • Vanadium was first used extensively in the automobile industry to build the Model T Ford. Early Model T advertisements claimed vanadium steel was the toughest and most enduring steel ever manufactured and used throughout the frame of the car.
  • Vanadium is found in 65 different minerals.
  • Vanadium is used in nuclear reactors because of its low neutron absorbing properties.
  • Vanadium pentoxide (V2O5) is used as a catalyst in the production of sulfuric acid.
  • Vanadium is found in the blood cells of some marine life. These proteins are known as vanabins.
  • Vanadium is an essential nutrient in very small doses, but vanadium compounds are mostly considered toxic to humans.

Learn more about elements on the periodic table.

Titanium Facts

Titanium is the 22nd element of the periodic table. These titanium facts contain chemical and physical data along with general information and history.

Element cell for Titanium

Titanium Periodic Table Cell

Basic Titanium Facts

Name: Titanium

Atomic Number: 22

Element Symbol: Ti

Group: 4

Period: 4

Block: d

Element Family: Transition Metal

Atomic Mass: 47.867(1)

Electron Configuration: [Ar]3d24s2
Full: 1s22s22p63s23p63d24s(full)

Discovery: William Gregor in 1791

Reverend William Gregor was an amature geologist who found a grainy, black sand in a stream near his parish of Mannacan in Cornwall, England. Further investigation showed the sand was part iron, part some unknown metal. He named his new metal manaccanite after his parish. He reported his discovery to the Royal Geological Society and moved on to other things.

Four years later, German chemist Martin Klaproth believed he found a new metal in the mineral rutile. He named his metal titanium after the Titans of Greek mythology. Klaproth learned of Gregor’s discovery and found Gregor’s manaccanite was identical to his titanium.

Name Origin: Titanium is named after the Titans of Greek mythology.

Isotopes:

Natural scandium is comprised of five stable isotopes: 46Ti, 47Ti, 48Ti, 49Ti and 50Ti. Twenty one radioactive isotopes exist ranging from 38Ti to 63Ti.

46Ti
Titanium-46 is a stable isotope containing 24 neutrons. 8.25% of natural titanium is titanium-46.

47Ti
Titanium-47 is a stable isotope containing 25 neutrons. 7.44% of natural titanium is titanium-47.

48Ti
Titanium-48 is a stable isotope containing 26 neutrons. 73.72% of natural titanium is titanium-48.

49Ti
Titanium-49 is a stable isotope containing 27 neutrons. 5.41% of natural titanium is titanium-49.

50Ti
Titanium-50 is a stable isotope containing 28 neutrons. 5.18% of natural titanium is titanium-50.


Titanium Crystal Bar

Bar of ultra-high purity titanium crystals. Credit: Heinrich Pnoik/Creative Commons

Physical Data

Density:  4.506  g/cm3

Melting Point: 1941 K ​(1668 °C, ​3034 °F)

Boiling Point: 3560 K ​(3287 °C, ​5949 °F)

State at 20ºC: Solid

Heat of Fusion: 14.15 kJ/mol

Heat of Vaporization: 425 kJ/mol

Molar Heat Capacity: 25.060 J/mol·K


Titanium atom

Electron shell configuration for titanium.

Atomic Data

Atomic Radius: 1.47 Å (empirical)

Covalent Radius: 1.60 Å

Van der Waals Radius:  1.48 Å

Electron Affinity: 7.622 kJ/mol

Electronegativity: 1.54

1st Ionization Energy: 658.813 kJ/mol

2nd Ionization Energy: 1309.837 kJ/mol

3rd Ionization Energy: 2652.546 kJ/mol

4th Ionization Energy: 4174.651 kJ/mol

5th Ionization Energy: 9581 kJ/mol

6th Ionization Energy: 11532.89 kJ/mol

7th Ionization Energy: 13585.1 kJ/mol

8th Ionization Energy: 16441.1 kJ/mol

Oxidation States: +4, +3 (common), +2, +1 (uncommon)


TiCl3

Aqueous titanium(III) chloride. Many titanium(III) compounds have this distinct violet color. Credit: W. Oelen/Creative Commons

Fun Titanium Facts

  • Titanium is a hard, shiny, strong metal at room temperature.
  • Titanium is used in many alloys. Titanium has the largest strength to density ratio of all the metals. Titanium adds high temperature resistance to alloys in addition to lightweight strength.
  • Titanium resists corrosion. Titanium is used to protect the hulls of ships and submarines from seawater.
  • Titanium is used in joint replacement surgeries because titanium bonds well with bones and is non-toxic to other tissues.
  • Titanium is the ninth most abundant element in the Earth’s crust (0.63% by mass).
  • Titanium is the seventh most abundant metal in the Earth’s crust.
  • Pure titanium proved difficult to isolate. Pure titanium metal was not produced until 1910 by New Zealand metallurgist Matthew A. Hunter.
  • Titanium(III) compounds are often violet in color.
  • One of the largest uses of titanium is in paint. Titanium(IV) oxide (or titanium dioxide) in paint makes a bright white color.
  • Titanium(IV) oxide is used in sunscreen products. Small particles of titanium oxide are invisible on skin but block UV light.
  • Titanium is a relatively inert substance. This makes it ideal for hypoallergenic jewelry to be made from titanium.

Learn more about elements on the periodic table.

Scandium Facts

Scandium is the 21st element of the periodic table. These scandium facts contain chemical and physical data along with general information and history.

Element cell for Scandium

Scandium periodic table cell.

Basic Scandium Facts

Name: Scandium

Atomic Number: 21

Element Symbol: Sc

Group: 3

Period: 4

Block: d

Element Family: Transition Metal

Atomic Mass: 44.955 908(5)

Electron Configuration: [Ar]3d14s2
Full: 1s22s22p63s23p63d14s(full)

Discovery: Lars Frederik Nilson in 1879

Mendeleev predicted the existence of an element between calcium and titanium because there was a gap in the atomic weights. Many chemists began searching for this element, but Swedish chemist Lars Nilson extracted scandium from a sample of the mineral euxenite. He extracted an oxide of ytterbium and an unknown element with an atomic weight of about 44. This placed the element in the position on the periodic table belonging to be Mendeleev’s missing element.

Name Origin: Scandium gets its name from the Latin Scandia which was the name for Scandinavia.

Isotopes:

Natural scandium is comprised of only one stable isotope 45Sc. Twenty three radioactive isotopes exist ranging from 37Sc to 60Sc.

45Sc
Scandium-45 is a stable isotope containing 24 neutrons. 100% of natural scandium is scandium-45.


Scandium

Scandium slabs and a cube of pure scandium. Credit: Heinrich Pnoik/Creative Commons

Physical Data

Density:  2.99 g/cm3

Melting Point: 1814 K ​(1541 °C, ​2806 °F)

Boiling Point: 3109 K ​(2836 °C, ​5136 °F)

State at 20ºC: Solid

Heat of Fusion: 14.1 kJ/mol

Heat of Vaporization: 332.7 kJ/mol

Molar Heat Capacity: 25.52 J/mol·K


Scandium atom

Electron shell configuration for scandium.

Atomic Data

Atomic Radius: 1.62 Å (empirical)

Covalent Radius: 1.70 Å

Van der Waals Radius:  2.11 Å

Electron Affinity: 18.139 kJ/mol

Electronegativity: 1.36

1st Ionization Energy: 633.088 kJ/mol

2nd Ionization Energy: 1234.99 kJ/mol

3rd Ionization Energy: 2388.655 kJ/mol

4th Ionization Energy: 7090.65 kJ/mol

5th Ionization Energy: 8842.88 kJ/mol

6th Ionization Energy: 10679 kJ/mol

7th Ionization Energy: 13315 kJ/mol

8th Ionization Energy: 15254.3 kJ/mol

Oxidation States: +3 (common), +2, +1 (uncommon)


Aquamarine Mineral - Beryl Crystal (Rob Lavinsky, iRocks.com)

Aquamarine Mineral – Beryl Crystal The color is due to the presence of scandium. (Rob Lavinsky, iRocks.com)

Fun Scandium Facts

  • Scandium is a silvery-white relatively light and soft metal at room temperature. When exposed to air, pure scandium develops a pink-yellow oxidation layer.
  • Scandium is used in alloys much like aluminum. Scandium has a higher melting point than aluminum while having nearly the same density.
  • Scandium is considered a rare-earth element because it is often found in rare-earth ores. It also shares many of the same chemical properties of other rare-earths.
  • Scandium is the 35th most abundant element in the Earth’s crust.
  • Scandium is the 23rd most abundant element in the Sun.
  • Scandium is the first of the transition metals.
  • Scandium-46 is a radioisotope used as a tracer to detect leaks in underground pipes. It is also used in oil refining to monitor the process.
  • Scandium iodide is used in mercury vapor lights to produce light similar to sunlight to for photography and film.
  • The color associated with aquamarine gemstones is due to the presence of scandium.
  • Scandium is produced as a byproduct during uranium refinement.

Learn more about elements on the periodic table.

Calcium Facts

Calcium is the 20th element of the periodic table. These calcium facts contain chemical and physical data along with general information and history.

Element cell for Calcium

Calcium periodic table cell

Basic Calcium Facts

Name: Calcium

Atomic Number: 20

Element Symbol: Ca

Group: 2

Period: 4

Block: s

Element Family: Alkaline Earth

Atomic Mass: 40.078(4)

Electron Configuration: [Ar]4s2
Full: 1s22s22p63s23p64s(full)

Discovery: Sir Humphry Davy in 1808

Davy is well known for his electrolysis experiments. He would place his instrument in samples of various common chemicals and observe what collects at the electrodes. He isolated pure calcium from a paste of lime (calcium oxide) using a mercury electrode. An solid amalgam of calcium and mercury formed when current was applied. Davy then used chemical techniques to remove the mercury and solid calcium remained.

Name Origin: Calcium got its name from the Latin name for lime, calx.

Isotopes:

Natural calcium is comprised of six isotopes: 40Ca, 42Ca, 43Ca, 44Ca, 46Ca, and 48Ca.
Five stable and nineteen radioactive isotopes exist ranging from 34Ca to 57Ca.

40Ca
Calcium-40 is a stable isotope containing 20 neutrons. 96.941% of natural calcium is calcium-40. Calcium-40 is theorized to actually be a radioactive isotope with an extremely long half-life (~1021 years) based on its internal structure. No one has ever detected a decay of a calcium-40 atom.

42Ca
Calcium-42 is a stable isotope containing 22 neutrons. 0.647% of natural calcium is calcium-42.

43Ca
Calcium-43 is a stable isotope containing 23 neutrons. 0.135% of natural calcium is calcium-43.

44Ca
Calcium-44 is a stable isotope containing 24 neutrons. 2.086% of natural calcium is calcium-44.

46Ca
Calcium-46 is a stable isotope containing 26 neutrons. 0.004% of natural calcium is calcium-46.
As with calcium-40, the internal structure of the calcium-46 atom is theoretically unstable and could be radioactive. No one has ever observed the decay of a calcium-46 atom.

48Ca
Calcium-48 is almost a stable isotope containing 28 neutrons. Calcium-48 has been observed to decay into titanium-48 by double β- decay. The half-life of this decay has been calculated to 3.338 x 1021 years. This decay makes calcium-48 the lightest isotope to undergo double β- decay. 0.187% of natural calcium is calcium-48.


Calcium Metal (Tomihahndorf)

Calcium Metal (Tomihahndorf)

Physical Data

Density:  1.54 g/cm3

Melting Point: 1115 K ​(842 °C, ​1548 °F)

Boiling Point: 1757 K ​(1484 °C, ​2703 °F)

State at 20ºC: Solid

Heat of Fusion: 8.54 kJ/mol

Heat of Vaporization: 154.7 kJ/mol

Molar Heat Capacity: 25.929 J/mol·K


Calcium atom

Electron shell configuration for calcium.

Atomic Data

Atomic Radius: 1.97 Å (empirical)

Covalent Radius: 1.76 Å

Van der Waals Radius:  2.31 Å

Electron Affinity: 2.369 kJ/mol

Electronegativity: 1.00

1st Ionization Energy: 589.83 kJ/mol

2nd Ionization Energy: 1145.447 kJ/mol

3rd Ionization Energy: 4912.368 kJ/mol

4th Ionization Energy: 5876.92 kJ/mol

5th Ionization Energy: 8153 kJ/mol

6th Ionization Energy: 10495.68 kJ/mol

7th Ionization Energy: 12272.9 kJ/mol

8th Ionization Energy: 14206.5 kJ/mol

Oxidation States: +2 (common), +1, -1 (uncommon)


Calcium Flame Test

Calcium flame test. Credit: Herge/Creative Commons

Fun Calcium Facts

  • Calcium is a soft silvery metal at room temperature. Left alone, it will quickly oxidize in air forming a dull grey patina.
  • Calcium burns with a bright orange-red flame in a flame test.
  • Calcium is used in fireworks to add orange color.
  • Calcium is the fifth most abundant element in the human body. Nearly all the calcium in your body is in your teeth and bones.
  • Vitamin D is vital for the absorption of calcium in your body.
  • Calcium is the fifth most abundant element in the Earth’s crust, accounting for approximately 4.1% by mass.
  • Calcium is not found native in nature. It is always part of another compound.
  • Sea creature shells are mostly calcium carbonate.
  • Calcium can be found abundantly in limestone (calcium carbonate), gypsum (calcium sulfate), fluorite (calcium fluoride) and apatite (calcium-chloro-( or fluoro-) phosphate.
  • Calcium is produced commercially by heating lime (calcium oxide) with aluminum in a low pressure environment.
  • Calcium is used for making cement, making cheese, removing nonmetallic impurities from alloys, and as a reduction agent in the preparation of other metals.
  • Calcium was known to exist for centuries before Davy identified it as an element.

Learn more about elements on the periodic table.

Potassium Facts

Potassium is the 19th element of the periodic table. These potassium facts contain chemical and physical data along with general information and history.

Element cell for Potassium

Potassium periodic table cell

Basic Potassium Facts

Name: Potassium

Atomic Number: 19

Element Symbol: K

Group: 1

Period: 4

Block: s

Element Family: Alkali Metal

Atomic Mass: 39.0983(1)

Electron Configuration: [Ar]4s1
Full: 1s22s22p63s23p64s(full)

Discovery: Sir Humphry Davy in 1807

Davy is well known for his electrolysis experiments. He would place his instrument in samples of various common chemicals and observe what collects at the electrodes. He isolated pure potassium metal from potash (potassium hydroxide).

Name Origin: Potassium was named from its source: potash. Potash was formed from wood ashes soaked in water.

Element Symbol Origin: The K symbol for potassium comes from the Latin name for potash, kalium. German and Scandinavian chemists used the name kalium for potassium in their texts and journals.

Isotopes:

Natural potassium is comprised of three isotopes: 39K, 40K and 41K.
Two stable and twenty two radioactive isotopes exist ranging from 32K to 56K.

39K
Potassium-39 is a stable isotope containing 20 neutrons. 93.2581% of natural potassium is potassium-39.

40K
Potassium-40 is a radioactive isotope containing 21 neutrons. Most of the time, potassium-40 decays by β- decay into 40Ca, but it can also decay β+ decay or electron capture into 40Ar with a half-life of 1.2 billion years. Potassium-40 accounts for 0.117% of natural potassium.

41K
Potassium-41 is a stable isotope containing 22 neutrons. 6.7302% of natural potassium is potassium-39.


Potassium Metal

Small sample of potassium metal under oil. Credit: Creative Commons

Physical Data

Density:  0.89 g/cm3

Melting Point: 336.7 K ​(63.5 °C, ​146.3 °F)

Boiling Point: 1032 K ​(759 °C, ​1398 °F)

Critical Point: 2223 K at 16 MPa

State at 20ºC: Solid

Heat of Fusion: 2.33 kJ/mol

Heat of Vaporization: 76.9 kJ/mol

Molar Heat Capacity: 29.6 J/mol·K


Potassium atom

Electron shell configuration for potassium.

Atomic Data

Atomic Radius: 2.27 Å (empirical)

Covalent Radius: 2.03 Å

Van der Waals Radius:  2.75 Å

Electron Affinity: 48.385 kJ/mol

Electronegativity: 0.82

1st Ionization Energy: 418.81 kJ/mol

2nd Ionization Energy: 3051.83 kJ/mol

3rd Ionization Energy: 4419.607 kJ/mol

4th Ionization Energy: 5876.92 kJ/mol

5th Ionization Energy: 7975.48 kJ/mol

6th Ionization Energy: 9590.6 kJ/mol

7th Ionization Energy: 11995.347 kJ/mol

8th Ionization Energy: 13841.79 kJ/mol

Oxidation States: +1 (common), -2 (uncommon)


Potassium Flame Test

Potassium flame test. Potassium burns with a bright red light. Credit: Herge/Public Domain

Fun Potassium Facts

  • Potassium is a shiny, lustrous metal at room temperature. When exposed to air, an oxidizing layer forms quickly, turning its appearance to a dull gray.
  • Potassium vigorously reacts with water to form hydrogen gas. This gas can ignite from the energy released from the reaction, giving the impression the potassium burns in water.
  • Potassium was the first metal to be discovered by electrolysis.
  • Potassium has a low density for a metal. Pure potassium metal will float on water.
  • Potassium burns with a bright red in a flame test. When in water, the flame takes on a lilac colored hue.
  • Potassium is the seventh most abundant element in the human body.
  • Potassium is the seventh most abundant element in the Earth’s crust, accounting for 4.2% by mass.
  • The largest industrial use of potassium is for fertilizer.
  • Potassium is used in soaps, gunpowder, bleaching agents and glass making.
  • Potassium-40 is used much like carbon-14 as a radioactive dating marker. K-40 is used to determine the age of rock formations.

Learn more about elements on the periodic table.

Argon Facts

Argon is the 18th element of the periodic table. These argon facts contain chemical and physical data along with general information and history.

Element cell for Argon

Argon Periodic Table Cell

Basic Argon Facts

Name: Argon

Atomic Number: 18

Element Symbol: Ar

Group: 18

Period: 3

Block: p

Element Family: Noble Gas

Atomic Mass: 39.948(1)

Electron Configuration: [Ne]3s23p6 (shorthand) or 1s22s22p63s23p(full)

Discovery: Lord Rayleigh and Sir William Ramsay in 1894

Rayleigh noticed a difference in density between nitrogen obtained from the air and nitrogen obtained through chemical reactions. He also noticed oxygen was the same density, no matter how you obtained it. Ramsay heard of this problem and began to collaborate with Rayleigh. Ramsay designed a method to remove oxygen, carbon dioxide and nitrogen from a volume of air. Once finished, he found there was still a small amount of gas remaining. The leftover gas did not react with any other chemical. His spectral analysis showed the gas was an unknown element.

Name Origin: Argon gas was completely unreactive with other chemicals, almost like argon was too lazy to react. Ramsay and Rayleigh named argon from the Greek word argos meaning lazy or inactive.

Isotopes:

Natural argon is comprised of three stable isotopes: 36Ar, 38Ar and 40Ar. Twenty one radioactive isotopes exist ranging from 30Ar to 53Ar.

36Ar
Argon-36 is a stable isotope containing 18 neutrons. 0.3336% of natural argon is argon-35.

38Ar
Argon-37 is a stable isotope containing 20 neutrons. .0629% of natural argon is argon-38.

40Ar
Argon-40 is a stable isotope containing 22 neutrons. 99.6035% of natural argon is argon-40.

Argon-39 is a radioactive isotope containing 21 neutrons. It is formed when cosmic radiation interacts with atmospheric argon-40. Argon-39 decays by β- decay into 39K with a half-life of 269 years and can be found naturally in trace quantities.


Argon Ice

Small sample of melting solid argon. Credit: Deglr6328/Creative Commons

Physical Data

Density:  0.001633 g/cm3

Melting Point: 83.81 K ​(−189.34 °C, ​−308.81 °F)

Boiling Point: 87.302 K ​(−185.848 °C, ​−302.526 °F)

Triple Point: 83.8058 K at ​68.89 kPa

Critical Point: 150.687 K at 4.863 MPa

State at 20ºC: Gas

Heat of Fusion: 1.18 kJ/mol

Heat of Vaporization: 6.53 kJ/mol

Molar Heat Capacity: 20.85 J/mol·K


Chlorine Atom

Electron shell configuration of a chlorine atom.

Atomic Data

Atomic Radius: 1.88 Å

Covalent Radius: 1.06 Å

Van der Waals Radius:  1.88 Å

Electron Affinity: not stable

Electronegativity: unknown

1st Ionization Energy: 1520.571 kJ/mol

2nd Ionization Energy: 2665.857 kJ/mol

3rd Ionization Energy: 3930.81 kJ/mol

4th Ionization Energy: 5770.79 kJ/mol

5th Ionization Energy: 7238.33 kJ/mol

6th Ionization Energy: 8781.034 kJ/mol

7th Ionization Energy: 11995.347 kJ/mol

8th Ionization Energy: 13841.79 kJ/mol

Oxidation States: +7, +5, +1, -1 (common), +6, +6, +2 (uncommon)


Argon Discharge Tube

Argon in a discharge tube. Argon emits a violet light when ionized. Credit: Alchemisthp/Creative Commons

Fun Argon Facts

  • Argon is a colorless, odorless gas at room temperature. When ionized, argon emits a distinctive violet glow.
  • Argon is produced industrially by cryogenically distilling air.
  • Argon only accounts for 0.94% by volume of the gasses in the atmosphere. Yet, it is the third most plentiful gas in air.
  • Argon is the go-to gas when an inert environment is needed.
  • Argon is used in fire-suppression systems. The argon displaces the oxygen in a room and combustion stops.
  • Argon is added to incandescent lights to protect the filament from oxygen. It is also widely used in fluorescent bulbs.
  • Double paned windows use argon between the panes to act as an insulator.
  • Argon has no known biological role.
  • Argon-39 is used much like carbon-14 to date water and ice samples.
  • Prior to 1957, the element symbol for argon was A. The IUPAC changed it to the Ar we know today.

Learn more about elements on the periodic table.

Chlorine Facts

Chlorine is the 17th element of the periodic table. These chlorine facts contain chemical and physical data along with general information and history.

Element cell for Chlorine

Chlorine Periodic Table Cell

Basic Chlorine Facts

Name: Chlorine

Atomic Number: 17

Element Symbol: Cl

Group: 17

Period: 3

Block: p

Element Family: Halogen

Atomic Mass: [35.446; 35.457]
IUPAC guidelines to reflect the physical and chemical history of the magnesium sample. If a single value of the atomic mass is needed, use 35.4527.

Electron Configuration: [Ne]3s23p5 (shorthand) or 1s22s22p63s23p(full)

Discovery: Carl Wilhelm Scheele in 1774

Scheele isolated chlorine from hydrochloric acid. He thought the yellow gas he collected was an oxide of another compound, not a new element. This belief continued until 1811 when Sir Humphry Davy showed there was no oxygen in chlorine gas. Chlorine was its own element.

Name Origin: Davy named the new element chlorine from the Greek word chloros meaning yellow-green.

Isotopes:

Natural chlorine is comprised of two stable isotopes: 35Cl, and 37Cl. Twenty two radioactive isotopes exist ranging from 28Cl to 51Cl.

35Cl
Chlorine-35 is a stable isotope containing 18 neutrons. 75.77% of natural chlorine is chlorine-35.

37Cl
Chlorine-37 is a stable isotope containing 20 neutrons. 24.23% of natural chlorine is chlorine-37.

36Cl
Chlorine-36 is a radioactive isotope containing 19 neutrons. It is formed when cosmic radiation interacts with atmospheric chlorine. Chlorine-36 decays by β- decay into 36Ar 98.1% of the time or 36S by electron capture 1.9% of the time. The half-life is 301,200 years and can be found naturally in trace quantities.


Liquid Chlorine

Liquid chlorine in a flask. Credit: Workingclass91/Creative Commons

Physical Data

Density:
(gas) 0.002898 g/cm3
(liquid at boiling point) 1.5625 g/cm3

Melting Point: 171.6 K ​(−101.5 °C, ​−150.7 °F)

Boiling Point: 239.11 K ​(−34.04 °C, ​−29.27 °F)

Critical Point: 416.9 K at 7.991 MPa

State at 20ºC: Gas

Heat of Fusion: 6.406 kJ/mol for Cl2

Heat of Vaporization: 20.41 kJ/mol for Cl2

Molar Heat Capacity: 33.949 J/mol·K for Cl2


Chlorine Atom

Electron shell configuration of a chlorine atom.

Atomic Data

Atomic Radius: 1.75 Å

Covalent Radius: 1.02 Å

Van der Waals Radius:  1.75 Å

Electron Affinity: 348.575 kJ/mol

Electronegativity: 3.16

1st Ionization Energy: 1251.186 kJ/mol

2nd Ionization Energy: 2297.663 kJ/mol

3rd Ionization Energy: 3821.78 kJ/mol

4th Ionization Energy: 5158.608 kJ/mol

5th Ionization Energy: 6541.7 kJ/mol

6th Ionization Energy: 9361.97 kJ/mol

7th Ionization Energy: 11018.221 kJ/mol

8th Ionization Energy: 33603.91 kJ/mol

Oxidation States: +7, +5, +1, -1 (common), +6, +6, +2 (uncommon)


Fun Chlorine Facts

  • Chlorine rarely occurs freely in nature. You are much more likely to find chlorine combined with other elements (such as table salt NaCl) or itself the form Cl2.
  • Chlorine is the third most abundant element in the Earth’s oceans.
  • Chlorine is the 21st most abundant element in the Earth’s crust.
  • Chlorine is the ninth most abundant element in the human body.
  • Chlorine gas is has a yellow-green color and a strong smell.
  • The smell of chlorine is an irritant. Humans can detect the smell at concentrations as low as 3.5 parts per million.
  • Chlorine was an early chemical weapon. It reacts with the mucous membranes and can burn the skin. Concentrations around 1000 parts per million are typically fatal after a few breaths. Chlorine gas is also denser than air and would settle in low lying areas such as trenches and foxholes.
  • Leaking chlorine containers are hazardous. Leaks in containers are detected using ammonia. The ammonia reacts with the chlorine and forms a white mist near the leak.
  • Chlorine appears often in organic chemistry reactions where it replaces hydrogen atoms in molecules.
  • Chlorine is used in the manufacture of a multitude of products such as plastics, paper, medicine, insecticides, disinfectants, textiles, dyes and petroleum products. It is commercially extracted by electrolysis from brine solutions.
  • Scheele’s name for chlorine was muriaticum. The old name for hydrochloric acid was muriatic acid.

Learn more about elements on the periodic table.