Chemistry (18BSCH03) Jan-June 2020
Question Bank (Module 2)
odule 2
Periodic properties and Molecular structure
S.N Questions Marks
o
1 Explain the Periodic trends of atomic radius and electro negativity 7
ionization energy and electron affinity?
Atomic size: In homo nuclear diatomic molecules the distance from the
centre of one nucleus to the centre of another nucleus gives the bond
length and half of this bond length is atomic radius.
Down the group atomic radius increases, This increase may be
explained in terms of a new electron shell being added, when we pass
from one element to another in a group.
Along the period atomic radius decreases, as electrons fall into same
shell.
Ionization Energy: is the energy required to remove the most loosely
bound electron from an isolated atom in the gaseous state.
As we move from left to right in the periodic table, there is a nearly
regular increase in the of the ionization energy. Similarly, on moving
down a group the ionization energy decreases.
Electron Affinity: is the energy released or adsorbed for one mole of
neutral atoms in a gaseous state when electron is accepted by each atom.
As we move from left to right in the periodic table, there is a nearly
regular increase in the of the Electron affinity. Similarly, on moving
down a group the Electron affinity decreases.
Electronegativity: is defined as a measure of the ability of an atom to
, attract the Electron pair in a covalent bond to itself.
As we move from left to right in the periodic table, there is a nearly
regular increase in of the Electronegativity. Similarly, on moving down
a group the Electronegativity decreases.
2 What is crystal field splitting energy? Explain octahedral splitting with 8
diagram.
The Crystal Field Theory (CFT) is a model for the bonding
interaction between transition metals and ligands
It describes the effect of the attraction between the positive
charge of the metal cation and negative charge on the non-
bonding electrons of the ligand.
The five d-orbitals are given the symbols dxy, dzx, dyz, dx2-y2
and dz2.
dxy, dyz, dzx are grouped under t2g set, dx2-y2, dz2 are grouped under eg. dx2-
, dz2 are placed along the axis, dxy, dyz, dzx are placed in between the
y2
axis.
dx2-y2, dz2 of the d-orbitals will point directly towards the ligands as
ligand approaches along the axis in octahedral complex,
so eg will experience more repulsion between their own
electrons and those of the incoming ligands, hence eg splits to
higher energy level.
Question Bank (Module 2)
odule 2
Periodic properties and Molecular structure
S.N Questions Marks
o
1 Explain the Periodic trends of atomic radius and electro negativity 7
ionization energy and electron affinity?
Atomic size: In homo nuclear diatomic molecules the distance from the
centre of one nucleus to the centre of another nucleus gives the bond
length and half of this bond length is atomic radius.
Down the group atomic radius increases, This increase may be
explained in terms of a new electron shell being added, when we pass
from one element to another in a group.
Along the period atomic radius decreases, as electrons fall into same
shell.
Ionization Energy: is the energy required to remove the most loosely
bound electron from an isolated atom in the gaseous state.
As we move from left to right in the periodic table, there is a nearly
regular increase in the of the ionization energy. Similarly, on moving
down a group the ionization energy decreases.
Electron Affinity: is the energy released or adsorbed for one mole of
neutral atoms in a gaseous state when electron is accepted by each atom.
As we move from left to right in the periodic table, there is a nearly
regular increase in the of the Electron affinity. Similarly, on moving
down a group the Electron affinity decreases.
Electronegativity: is defined as a measure of the ability of an atom to
, attract the Electron pair in a covalent bond to itself.
As we move from left to right in the periodic table, there is a nearly
regular increase in of the Electronegativity. Similarly, on moving down
a group the Electronegativity decreases.
2 What is crystal field splitting energy? Explain octahedral splitting with 8
diagram.
The Crystal Field Theory (CFT) is a model for the bonding
interaction between transition metals and ligands
It describes the effect of the attraction between the positive
charge of the metal cation and negative charge on the non-
bonding electrons of the ligand.
The five d-orbitals are given the symbols dxy, dzx, dyz, dx2-y2
and dz2.
dxy, dyz, dzx are grouped under t2g set, dx2-y2, dz2 are grouped under eg. dx2-
, dz2 are placed along the axis, dxy, dyz, dzx are placed in between the
y2
axis.
dx2-y2, dz2 of the d-orbitals will point directly towards the ligands as
ligand approaches along the axis in octahedral complex,
so eg will experience more repulsion between their own
electrons and those of the incoming ligands, hence eg splits to
higher energy level.
