Describe the relationship between
a. the radius of a cation and that of the atom from which it is formed.
b. the radius of an anion and that of the atom from which it is formed.
Solution 32 E:Here, we are going to discuss about the covalent bond.Covalent bond is defined as the sharing of electrons between atoms. All atoms are covalentlybonded to each other to gain stability. Atom should be shared their electrons to satisfy the octetrule.The Octet Rule is satisfied when all atoms in a molecule to have 8 valence electrons eitherby sharing, losing or gaining electrons to become stable. This is because only 8 electrons arerequired to fulfil the s and p- orbital of electronic configuration which is also known as Noblegas configuration.The atomic number of S is = 16The electronic configuration of S is [Ne] 3s 3p . The outer valence shell has only 6 electrons. Soit requires only two electrons to fulfill the octet rule. Therefore S can form covalent bond bysharing its electrons with other atom.The atomic number of H is = 1The electronic configuration of H is 1s 1The outer valence shell has only1 electron. So it requires only one electron to achieving thenoble gas configuration of He atom. Therefore H can form covalent bond by sharing its electronwith other atom.The atomic number of K is = 19 1The electronic configuration of K is [Ar] 4sThe outer valence shell has only 1 electron. So it can easily donate that electron to become anoble gas configuration. So it unlikely form covalent bond.The atomic number of Ar is = 18 2 6The electronic configuration of Ar is [Ne] 3s 3pArgon can not form covalent bond. This is because Argon has a full outer valence shell.The atomic number of Si is = 14The electronic configuration of Ar is [Ne] 3s 3p2 2The outer valence shell has only 4 electrons. So it requires another four electrons to fulfill theoctet rule. Therefore Si can form covalent bond by sharing its electrons with other atom.Thus, non metals always can form covalent bond because of its partially filled outer valence shell(s and p-orbital).Therefore, S, H and Si can form covalent bonds easily whereas Ar is inactive and K isunlikely to form covalent bond.