The name 'carbon' is derived from the Latin word "carbo". Carbon is one of the most abundant nonmetallic chemical elements in the universe, and is placed fourth after hydrogen, helium, and oxygen. In humans, it is the second most abundant element behind oxygen.
Carbon is positioned in group 14 in the periodic table. Chemically, it is represented by the symbol C. Its atomic number is 6. This means that its outermost orbit carries four electrons, which can form covalent type of chemical bonds during chemical reactions. Carbon is found in nature in three isotopic forms. Carbon-12 and carbon-13 are stable, but carbon-14 is radioactive.
Physical Properties of Diamond and Graphite
Carbon in its atomic form is in a very transient state. Hence, in order to make it stable in multi-atomic structures, it is arranged in a wide variety of molecular configuration called allotropes. Diamond, graphite, and amorphous carbon are the most common allotropic forms of this element. The physical properties of these forms are very different from each other. While diamond is transparent, and also is the hardest of all substances, graphite is very soft and opaque. The former is a poor conductor of electricity, but the latter is a good conductor of the same type of energy. Graphite has lubricant properties, but diamond is used as an abrasive.
The element carbon is capable of forming long chains of carbon-carbon bonds, which are strong and stable in nature. This property is known as catenation, and hence, carbon compounds are found in infinite numbers. It is a fact that the number of these compounds are much higher than the compounds of any other element, except hydrogen.
Any organic molecule is made up of hydrocarbons, which can be described as a class of compounds, wherein hydrogen atoms are bonded with a chain of carbon atoms. The characteristics of an organic molecule depends upon the length of the carbon chain, its side chains, and the functional group that is associated with it.
When carbon bonds with oxygen and hydrogen, a large variety of important biological compounds are formed, like carbohydrates, alcohols, fats, esters, carotenoids, etc. Bonding between carbon and nitrogen leads to the formation of alkaloids. Addition of sulfur to these bonds lead to the formation of amino acids, antibiotics, and rubber products. When phosphorus is added to such elements, they form essential molecules like DNA, RNA (key components of living cells), and ATP (adenosine triphosphate: it is responsible for transfer of energy in all living cells), which are critical for life.
Those carbon compounds, which are found in minerals, and do not have any hydrogen or fluorine content, are usually not formulated as typically organic ones. Carbon reacts with oxygen to form carbon dioxide. When dissolved in water, it forms a weak acid known as carbonic acid, which is unstable in nature. Other examples of such bonds are carbides, carbonates, cyanides, calcites, etc.
Carbon is a major component of various foodstuffs that we eat. Another very important form of this element is with reference to the fossil fuels - coal, petroleum, oil, etc. The uses of elemental carbon innumerable. It is used with iron for manufacturing various types of alloys. Graphite is used to make lead pencils. It is an essential component of electrodes in dry batteries. It also acts as moderators in nuclear reactors. Diamonds are used in making jewelry. Carbon is also used in industries for the purpose of cutting, drilling, grinding, etc. Carbon-14 is a radioisotope of this element, which is used to determine the age of the fossils by means of a process called radiocarbon dating.
Without carbon compounds, formation of life forms is impossible. However, some compounds also are poisonous like carbon monoxide, tetrodoxotin, cyanides, etc. If carbon black is inhaled in large quantities, it can cause congestive lung diseases.
Besides being harmful in some forms, the element carbon is very useful to us in different ways, and is an important part of life on Earth. We are indeed lucky that this chemical element is in abundance in the Universe.