Short Answer TypeAn element A has the configuration 1s22s22p63s1 while the configuration of B is 1s22s22p5. What type of bond is likely to be formed between them?
Long Answer TypeDiscuss the Lewis concept of the covalent bond formation.
A chemical bond formed by the mutual sharing of one or more pairs of electrons between atoms of same or different elements so as to complete their octets is called the covalent bond. Each atom contributes an equal number of electrons for the process of sharing and number of electrons contributed by each atom is known as covalency.
A single bond is formed when atoms mutually share one pair of electrons. A double bond is formed when the atoms share two electron pairs. A triple bond is formed when the atoms share three electron pairs.
Examples:
(a) Homoatomic molecules (covalent bonds in similar atoms).
(i) Hydrogen molecule (H2): A covalent bond is formed between two hydrogen atoms by sharing a pair of electrons between them. Each atom contributes one electron for sharing.
(ii) Chlorine molecule (Cl2): Chlorine atom (17Cl) has seven electrons in its valence shell (2, 8, 7). In the formation of chlorine molecule, each chlorine atom contributes one electron for sharing in order to acquire a stable noble gas configuration (Argon).
(iii) An oxygen molecule (O2): Oxygen atom (8O) has six electrons in its valence shell (2, 6). In the formation of O2 molecule, each oxygen atom contributes two electrons for mutual sharing in order to acquire a stable neon configuration and forms divalent or double bond.
(iv) Nitrogen molecule (N2): Nitrogen atom (7N) has five electrons in its valence shell (2, 5). In the formation of N2 molecule, each nitrogen atom contributes three electrons for mutual sharing in order to acquire stable neon configuration and forms trivalent or triple bond.
(b) Heteroatomic molecules (covalent bonds in different atoms).
(i) Methane molecule (CH4): Carbon atom (6C) has four electrons in its valence shell (2, 4). Carbon atom forms four covalent bonds with four hydrogen atoms.
(ii) A water molecule (H2O): The oxygen atom is bonded to two hydrogen atoms.
(iii) Carbon dioxide molecule (CO2): Carbon atom is bonded to two oxygen atoms with double bonds.
Short Answer TypeWhat do you understand by bond pairs and lone pairs of electrons? Illustrate by giving one example of each type.
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