Chemistry
(a) Define covalent (molecular) bond.
(b) Give an example of covalent bond formed by
(i) similar atoms
(b) dissimilar atoms
Answer
(a) Covalent Bond — The chemical bond that is formed between two combining atoms by mutual sharing of one or more pair of electrons is called a covalent bond. Depending on the number of electron pairs shared : bond is single [-], double [=], or triple [≡] covalent.
(b) (i) Bond formed between two H atoms; H-H
A hydrogen atom has one electron in its only shell. It needs one more electron to attain duplet. To meet this need, hydrogen atom shares its electron with another hydrogen atom. Thus, one electron each is contributed by the two atoms of hydrogen, and the resulting pair of electrons is mutually shared by both the atoms to form a hydrogen molecule.
(ii) Bond formed between a hydrogen atom and chlorine atom; H‒Cl
In the case of hydrogen chloride molecule, hydrogen atom shares an electron pair with chlorine atom, such that hydrogen acquires a duplet configuration and chlorine an octet, resulting in the formation of a single covalent bond.
Related Questions
Give the terms for the following definitions:
(a) A bond formed by a shared pair of electrons, each bonding atom contributing one electron to the pair.
(b) A bond formed by transfer of electron(s).
Name or state the following.
(a) An element having valency zero.
(b) Metal with valency one.
(c) Atoms of the same element differing in mass numbers.
(d) Elements having same mass number but different atomic number.
(e) Bond formed by transfer of electrons(s)
(f) Ion formed by gain of electron(s)
An element A has 1 electron in its first shell. It combines with element B having 7 electrons in its third shell. What type of bond is formed ?
If electrons are getting added to an element Y; then
(a) what charge will Y have?
(b) is Y getting oxidized or reduced ?