Krypton difluoride is the chemical name of KrF2. It was the first discovered compound of krypton. It exists as a colorless solid with volatile nature.
Krypton difluoride
is considered a strong oxidizing and fluorinating agent. It is so powerful as
it can oxidize gold and silver too.
7 KrF2 (g) + 2 Au (s) → 2 Kr+ AuF6- (s) + 5 Kr (g)
KrF2 (g) + AgF (s) → AgF3 (s) + Kr (g)
Here in
this article, we are going to learn whether KrF2 is a polar molecule or a nonpolar
molecule in detail. But before that first have some ideas about what polar and
nonpolar molecules are:
Polar Molecule
Those molecules
that have a net dipole charge are called polar molecules. In simple terms, if
there is an electronegativity difference between two atoms within the molecule,
induced partial positive and negative charges on either end of the bond. These
types of bonds are called polar bonds.
But being a polar bond is only not enough to make a molecule polar for that molecule must have
an asymmetrical structure so that the induced charges do not cancel.
Xenon difluoride (XeF2), Water (H2O), etc. are some of the examples of polar molecules.
Nonpolar Molecule
Those
molecules that have zero dipole moment/charge are called nonpolar molecules. It means
if the molecules contain two atoms with two different electronegativity values,
they are referred to as polar molecules. However, a molecule can be nonpolar despite having multiple polar bonds only if the molecule is symmetrical.
Xenon tetrafluoride (XeF4), ethane (C2H6), benzene (C6H6), etc. are some of the examples
of polar molecules.
Checkout:
Difference Between Polar & Nonpolar Molecules With Examples [In Detailed].
So, Is KrF2
polar or nonpolar? KrF2 is a nonpolar molecule because it has a linear molecule
geometry so that the induced dipole charge on both Kr-F bonds nullify each
other, as a result, the overall molecule has zero dipole charge.
KrF2 Polar or Nonpolar (Detailed Explanation)
These are some of the major aspects on which polarity of the molecules are used to determine:
Electronegativity difference
KrF2
molecule consists of three atoms where two fluorine is attached with a krypton
atom. The electronegativity difference between fluorine (F=3.98) and krypton
(Kr=3.0) is 3.98 – 3.0 = 0.98.
According to
the Pauli scale, if the electronegativity difference between two atoms is more
than 0.4 and less than 2.0, the bond between them is considered polar. In KrF2,
the electronegativity difference between Kr and F is 0.98, which means the Kr-F bond is
polar.
But KrF2
has linear geometry so the induced dipole charges are canceled out each other
and no charge localized on the molecule.
Lewis Structure of KrF2
Lewis dot
structure is a pictorial representation of covalent bonding between the combining
atoms. The valence electrons of each atom are represented in Lewis structure.
In KrF2
molecule, there are a total of 22 valence electrons present (8 from krypton and
14 from both fluorine). Both the fluorine atoms needed only one electron to
complete their octet so that they formed two single bonds with krypton
separately.
As you can
see, there are three pairs of electrons left on the krypton atom as they do not participate
in bond formation.
Molecular Geometry of KrF2
KrF2 has a linear molecule geometry where the bond angle between F-Kr-F is 180°. As you can see in the above Lewis diagram, there are 3 lone pairs of electrons present on the central atom Kr but their exerted force is also balanced as they are placed in equatorial position.
Dipole Moment of KrF2
Dipole
moment is the major aspect for any compound to be polar or nonpolar. In simple
terms, if the dipole moment of the molecule is zero, it is nonpolar and except that
all are polar.
As we
already know, the dipole moment is the product of induced charge on the
molecule and distance between the bonded atoms.
Here in the
KrF2, the charge on the molecule is zero that means the dipole moment of the molecule
is also zero. This is the main reason why KrF2 is a nonpolar molecule.
The electronegativity difference between Kr and F is 0.98. It means both
Kr-F bonds are polar despite this KrF2 (krypton difluoride) is a nonpolar
molecule because it has a linear molecular geometry.
As it has a linear molecular shape, the induced dipole charges on both Kr-F bonds cancel out each other and the net dipole charge on the molecule becomes zero.
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