Carbon and cobalt are both chemical elements that have some important similarities and differences. They are located relatively close to each other on the periodic table of elements, with carbon having atomic number 6 and cobalt having atomic number 27. Both are metals, but they have considerably different properties and uses.
Atomic Structure
Carbon has 6 protons, 6 neutrons and 6 electrons. Its electron configuration is 1s2 2s2 2p2. Cobalt has 27 protons, 32 neutrons and 27 electrons. Its electron configuration is [Ar] 3d7 4s2. Both carbon and cobalt have relatively simple electron configurations with s and p orbitals filled. However, cobalt also has partially filled d orbitals that contribute to its magnetic properties.
Physical Properties
Carbon commonly occurs in several allotropes including graphite and diamond. Graphite is soft and grayish-black in color while diamond is extremely hard and transparent. Diamond has a cubic crystal structure while graphite has a layered hexagonal structure. Cobalt is a hard, grayish, magnetic metal. It has a hexagonal close-packed crystal structure. Some key physical properties are compared below:
| Property | Carbon | Cobalt |
|---|---|---|
| Atomic mass | 12.011 g/mol | 58.933 g/mol |
| Density | 2.267 g/cm3 (graphite) | 8.9 g/cm3 |
| Melting point | 3550°C | 1495°C |
| Boiling point | 4827°C | 2927°C |
As the table shows, cobalt has a much higher density, melting point and boiling point compared to carbon. This reflects its metallic properties.
Chemical Properties
Carbon and cobalt have some differences in their chemical reactivity. Carbon is a nonmetal while cobalt is a transition metal.
Carbon can form covalent bonds with itself and other elements. It forms four bonds and so can create long chains and ring structures. This allows carbon to form the complex molecules that are the basis of life.
Cobalt commonly forms ionic and coordinate covalent bonds. It exists in oxidation states from -1 to +5, though +2 and +3 are the most common. Cobalt forms many coordination complexes with ligands like water and ammonia.
Cobalt metal slowly dissolves in acids and reacts with nonmetals like sulfur, selenium and phosphorus. At high temperatures, it burns in air forming cobalt(II)oxide.
Key Chemical Compounds
Some important chemical compounds containing carbon and cobalt are:
– Carbon dioxide (CO2) – a greenhouse gas produced by combustion and respiration.
– Methane (CH4)- a flammable hydrocarbon gas found in natural gas.
– Glucose (C6H12O6) – an essential carbohydrate molecule used for energy.
– Vitamin B12 (C63H88CoN14O14P) – an essential vitamin that contains a cobalt atom.
– Cobalt(II) chloride (CoCl2) – a blue solution used to make humidity indicators.
– Cobalt(II) sulfate (CoSO4) – a pink salt utilized in batteries and electroplating.
– Cobalt(II) nitrate (Co(NO3)2) – a red compound used to make pigments.
Occurrence and Production
In nature, carbon occurs as coal, graphite, diamond and in all living organisms. Cobalt occurs primarily in the minerals cobaltite, erythrite and glaucodot.
Carbon makes up 0.2% of the earth’s crust while cobalt makes up only 0.001%. Carbon production comes mainly from coal and petroleum. Cobalt is produced from ores like cobaltite that are mined in countries like Democratic Republic of Congo.
The leading producers of cobalt are Congo, Australia, Cuba, Zambia, Russia, Philippines and Canada. Cobalt production worldwide is around 100,000 tons per year.
Uses
Some of the major uses of carbon include:
– Fuel – Coal and natural gas are burnt to generate electricity.
– Steelmaking – Carbon is used to reduce iron ore and make steel.
– Refining – Charcoal filters are used to purify chemicals.
– Reinforcing agent – Carbon fibers reinforce plastics.
– Lubricants – Graphite is used as a dry lubricant.
Cobalt uses include:
– Alloys – It is alloyed with metals like iron and nickel to make superalloys.
– Batteries – Used in rechargeable lithium-ion batteries for phones and EVs.
– Catalysts – Used to catalyze chemical reactions like hydrogenation.
– Pigments – Cobalt compounds like cobalt blue give color to paints.
– Magnets – Alloyed with rare earths to make powerful magnets.
– Medicine – Cobalt-60 is used for radiation treatment of cancer.
Toxicity
Carbon as graphite and diamond is non-toxic. However, inhalation of carbon black or soot particles can cause lung damage. Prolonged skin contact with some carbon compounds like coal tar may cause irritation.
Cobalt has various toxic effects. Inhalation of cobalt dust can cause respiratory irritation and asthma-like symptoms. Exposure causes cardiomyopathy, vision problems and thyroid damage. Cobalt compounds are considered possible carcinogens. Radioactive cobalt-60 exposes people to gamma radiation.
Conclusion
In summary, carbon and cobalt are neighboring metals on the periodic table but have significantly different properties and applications. Carbon is non-metallic while cobalt is metallic and magnetic. Carbon forms strong covalent bonds that allow it to build large molecules. Cobalt forms ionic bonds and complexes. Both elements have a wide range of uses that rely on their unique chemistry. Carbon is essential to life while cobalt has diverse industrial and technological roles. At high exposures, both can have harmful health effects. Understanding their differences allows chemists to utilize carbon and cobalt in many essential ways.
