Chapter 1, Problem 40P

Interpretation Introduction

Interpretation:

For the following (a) high values of ionization energies are associated with the noble gases, (b) the enthalpy changes associated with the attachment of the first and second electrons to an O atom are exothermic and endothermic, (c) in Li atom in its ground state, the outer electron occupies a 2s rather than a 2p orbital, are to be explained.

Concept Introduction:

Distribution of electrons of an atom in the atomic orbitals in the increasing order of their atomic energies is known as electronic configuration.

The order of electronic configuration is 1s < 2s < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 5d $\approx$ 4f < 6p < 7s < 6d $\approx$ 5f

Electrons present in the outermost shell are called valence electrons and the electrons which occupies innermost shell or lowest energy levels are called core electrons.

n is the principal quantum number and it determines the number of shell.

l is azimuthal or orbital quantum number and has allowed the values 0, l, 2 . . (n-1). Value of l determines the shape of the atomic orbital, and orbital angular momentum of the electron.

${\text{m}}_{\text{l}}$ is the magnetic quantum number and gives information about the directionality of an atomic orbital and has integral value between +l to –l.

${\text{m}}_{\text{s}}$ is the spin quantum number and it determines the magnitude of the spin angular momentum of an electron and has a value of ½