It is a chemical bond formed between atoms by sharing of electron pairs.
Formation of Hydrogen molecule is an example of single covalent bond. We know that atomic number of Hydrogen is 1.That means hydrogen atom contain one proton in its nucleus and one electron in its shell. Hydrogen atom requires one more electron to attain nearest stable electronic configuration of inert gas (Helium).To achieve this two hydrogen atoms share one electron each to form a single covalent bond.
Formation of Oxygen molecule is an example of Double covalent Bond. The atomic number of oxygen is 8.That means oxygen atom contains 8 protons in its nucleus and it has 2 electrons in first shell and 6 electrons in second shell. Oxygen atom requires two more electrons to attain stable electronic configuration of nearest inert gas (Neon).Oxygen atom combines with another oxygen atom and share two electrons each to form a double covalent bond between two oxygen atoms.
Formation of Nitrogen molecule is an example of Triple covalent bond. Atomic number of nitrogen is 7.That means Nitrogen atom contains 7 protons in its nucleus, 2 electrons in its first shell and 5 electrons in second shell. Nitrogen atom requires 3 more electrons to attain stable electronic configuration of nearest inert gas (Neon).Nitrogen atom shares three electrons with another nitrogen atom and forms Triple covalent bond.
Other examples of covalent Bond are Methane, chloroform, carbon tetrachloride, Bromine, chlorine, Carbondioxide, Sulphuricdioxide, Sulphur trioxide, acetylene etc.
Ques: Which of the following compound is formed by covalent Bond?
Answer : Carbon dioxide is formed by the double covalent bonding between carbon and oxygen. Remaining compounds are formed by ionic bonding