Introduction
Cobalt is a transition metal located in group 9. Cobalt has 27 electrons. Its atomic number is 27 whereas its atomic mass is 58. The symbol of Cobalt is “Co”.
Naming and History
There are two origins of the Cobalt name. One is the Greek word “cobalos” which means “mines”. The other name was given by German miners. The old German word “kobold” means ‘goblin, evil spirit or elf’.
Cobalt has been in use by people since ancient civilizations. People of China and Rome used cobalt compounds for making ceramics and blue glass.
In 1735, Swedish chemist George Brandt was the first who discover and isolate cobalt. In 1739, he published his results. Before his publications, his claim disputed other chemists who thought his newly discovered element was a mixture of iron and arsenic. And the blue color was caused by Bismuth.
He explained in his publications that there is a new half-metal (transition metal) in addition to zinc, mercury, bismuth, and arsenic. He named cobalt after German miners who cursed it with the name kobold.
Occurrence of Cobalt
In nature, cobalt is not found freely and is not an abundant metal in Earth’s crust. It is present in ores. Cobalt is associated with copper and nickel and mined with them. Cobalt is present majorly in cobaltite, linnaeite, chloanthite, smaltite, carrollite, etc.
The largest miners and suppliers of cobalt are Canada, Russia, Australia, Cuba, etc.
Properties of Cobalt
Cobalt is a hard, sturdy, silvery bluish or whitish-grey transition metal with ferromagnetic properties. It is a brittle and lustrous element that has similar physical properties to iron and nickel.
Cobalt is a chemically active element but is stable in air. It remains unaffected by water. It can be easily magnetized and unlike any other magnetic can withstand high temperatures. Dilute acids react quickly with cobalt.
The melting point of cobalt is 1495°C and its boiling point is 2927°C. Cobalt has a density of 8.86 grams per cubic centimeter. Cobalt exists as a solid at room temperature.
Cobalt in Biological Systems
Cobalt is an essential trace element in living things. Cobalt is required for making active sites of enzymes and for their proper functioning. Cobalt is the central atom in vitamin B12. Cobalt is used to treat anemia as it regulates the production of red blood cells.
The animals which are mineral deficient are given cobalt. In aquatic environments, cyanobacteria and other nitrogen-fixing bacteria require it. It is slightly toxic to the skin but ingestion can cause health effects.
Cobalt-60 radioisotope is of great importance. It is used in the treatment and diagnosis of cancer.
Uses of Cobalt
Cobalt compounds are in use for centuries. It is magnetic but its alloy alnico, a combination of aluminum, nickel, and cobalt is used to make powerful magnets that are used in high-speed motors.
These magnets are also used in places where temperatures are very high.
Superalloys of cobalt are highly magnetic and corrosive resistant and are widely used in turbines, motor parts, etc.
Due to its non-corrosive nature, it is used in making aircraft parts, jet engines, speed steels, and cemented carbides.
Cobalt is widely used in electroplating.
It is used in making electronic batteries.
It is used as a catalyst in the chemical and petroleum industry to speed up reactions.
Cobalt is commonly used as a dying or coloring agent in paints, inks, glass, ceramics, etc.
Cobalt blue is used in pottery, porcelain dying, staining glass, jewelry enamel.
Cobalt 60, a radioisotope is a great source of gamma rays. These are used in sterilizing food products, medical equipment, and cancer treatment.
Isotopes of Cobalt
There are 22 isotopes of cobalt whose half-lives are known. Mass of them ranges from 50 to 72. The only stable isotope that exists in nature is Cobalt- 59. Cobalt- 60 is a radioactive isotope with a half-life of 5.27 years. It is an important medical tracer, source of gamma rays, and used in the treatment of cancer.
MCQs
- What is the atomic number of cobalt?
- A) 9
- B) 27
- C) 58
- D) 73
- Answer: B) 27
- What is the Greek origin of the name “Cobalt”?
- A) cobalos
- B) kobold
- C) elf
- D) mines
- Answer: A) cobalos
- Who was the first to discover and isolate cobalt in 1735?
- A) George Brandt
- B) Swedish chemists
- C) German miners
- D) Chinese and Roman civilizations
- Answer: A) George Brandt
- In nature, cobalt is often found associated with which metals?
- What are the major suppliers of cobalt globally?
- A) China, India, Brazil
- B) Canada, Russia, Australia
- C) USA, South Africa, Mexico
- D) Germany, France, Italy
- Answer: B) Canada, Russia, Australia
- What is the melting point of cobalt?
- A) 1137°C
- B) 1495°C
- C) 1844°C
- D) 2212°C
- Answer: B) 1495°C
- In biological systems, what is cobalt used for?
- A) Regulating red blood cell production
- B) Enhancing muscle growth
- C) Promoting bone density
- D) Improving vision
- Answer: A) Regulating red blood cell production
- What is the primary medical application of Cobalt-60?
- A) Treatment of anemia
- B) Sterilizing food products
- C) Boosting immune system
- D) Treating cancer
- Answer: D) Treating cancer
- What is the alloy alnico composed of?
- A) Iron, copper, and nickel
- B) Aluminum, nickel, and cobalt
- C) Gold, silver, and platinum
- D) Zinc, mercury, and arsenic
- Answer: B) Aluminum, nickel, and cobalt
- Why are superalloys of cobalt used in turbines and motor parts?
- A) Non-magnetic properties
- B) High corrosive resistance
- C) Low density
- D) Low melting point
- Answer: B) High corrosive resistance
- What is the only stable isotope of cobalt found in nature?
- A) Cobalt-50
- B) Cobalt-59
- C) Cobalt-60
- D) Cobalt-72
- Answer: B) Cobalt-59
- How many isotopes of cobalt have known half-lives?
- A) 15
- B) 18
- C) 22
- D) 30
- Answer: C) 22
- What is the primary use of cobalt in electroplating?
- A) Making powerful magnets
- B) Dying or coloring agent
- C) Catalyst in chemical industry
- D) Corrosion-resistant coatings
- Answer: D) Corrosion-resistant coatings
- In which industry is cobalt used as a catalyst to speed up reactions?
- A) Textile
- B) Food and beverage
- C) Petroleum and chemical
- D) Automotive
- Answer: C) Petroleum and chemical
- What is the radioisotope Cobalt-60 used for?
- A) Magnetic resonance imaging
- B) Sterilizing medical equipment
- C) Enhancing plant growth
- D) Water purification
- Answer: B) Sterilizing medical equipment
Summary
This comprehensive tutorial delves into the multifaceted aspects of cobalt, covering its introduction, naming, history, occurrence, properties, biological significance, uses, and isotopes.
Introduction: Cobalt, a transition metal in group 9 with 27 electrons and an atomic number of 27, plays a crucial role in various applications. Its symbol is “Co.”
Naming and History: The name “Cobalt” has dual origins, with the Greek word “cobalos” meaning “mines” and the German term “kobold” referring to goblins or evil spirits. Cobalt’s historical usage in ancient civilizations, particularly in China and Rome, is explored. Swedish chemist George Brandt’s discovery in 1735 is detailed, emphasizing the challenges he faced in establishing cobalt as a distinct element.
Occurrence of Cobalt: Cobalt is not freely found but is associated with copper and nickel in ores such as cobaltite, linnaeite, and smaltite. Major cobalt mining and supply regions include Canada, Russia, Australia, and Cuba.
Properties of Cobalt: Characterized as a hard, silvery bluish transition metal with ferromagnetic properties, cobalt shares physical traits with iron and nickel. Chemically active but stable in air, it can be magnetized and withstands high temperatures. The melting point is 1495°C, boiling point is 2927°C, and density is 8.86 grams per cubic centimeter.
Cobalt in Biological Systems: Essential as a trace element, cobalt contributes to enzyme activity and is a central atom in vitamin B12. It aids in treating anemia by regulating red blood cell production. Slightly toxic to the skin, cobalt-60 radioisotope finds applications in cancer treatment.
Uses of Cobalt: Cobalt compounds, known for centuries, form powerful magnets in alloys like alnico. Superalloys are used in turbines and motor parts, while its non-corrosive nature makes it valuable in aircraft and jet engines. Cobalt is widely employed in electroplating, electronic batteries, and as a catalyst in the chemical industry. It serves as a dying or coloring agent in paints, inks, and ceramics. Cobalt-60, a radioisotope, is a vital source of gamma rays used in sterilization and cancer treatment.
Isotopes of Cobalt: With 22 isotopes known, Cobalt-59 is the only stable isotope. Cobalt-60, a radioactive isotope with a half-life of 5.27 years, is crucial for medical tracing, gamma ray emission, and cancer treatment.
This tutorial provides a comprehensive understanding of cobalt, showcasing its historical significance, diverse applications, and pivotal role in various fields, from industry to healthcare.