According to VSEPR theory
The pairs of electrons tend to occupy such positions that place them farthest from each other and minimise repulsions.
In a bonded molecule, the order of repulsion between the bonded and non-bonded electrons is
Lone pair-lone pair lp - lp repulsions are considered stronger than lone pair-bonding pair lp - bp repulsions, which in turn are considered stronger than bonding pairbonding pair bp - bp repulsions, This is because the lone pair of electrons are attracted towards single nuclei only whereas bond pair electrons are attracted towards two nuclei. Thus the strength of the lone pair-lone pair repulsion is supposed to be more than bond pair-bond pair or bond pair-lone pair repulsion.
The shape of water molecule which should be tetrahedral has a bent or distorted tetrahedral shape with a bond angle 104.5°. What could be the reason for this?
Due to presence of lone pairs, the repulsion is more which changes the bond angle to 104.5°.
Which of the following shapes of SF4 is more stable and why?
In structure (ii), Ip-bp repulsions are minimum.
The most stable shape of ClF3 is shown by
In (i), the Ip are atequatorial position so there are less Ip - bp repulsions as compared to other positions.
Hence, T-shape is moststable.
In which of the following molecules the central atomdoes not retain any lone pair of electrons?
In all other molecules, N and O retain lone pair
Few examples of the compounds formed by chemical bonding are given below. Mark the incorrect example.
The correct example is H2O. NH3 is pyramidal and bond angle is 104.50.
Which of the following statements is correct regarding the structure of PCI5?
In PCI5, three axial and two equatorial bonds are present.
Match the molecules given in column I with their shapes given in column II and mark the appropriate choice
(A) SF6 − Octahedral
(B) SiCl4 − Tetrahedral
(C) AsF5 − Trigonal bipyramidal
(D) BCl3− Trigonal planar
What is common between the following molecules
SO3, CO2-3, No-3
All the moleculeshave trigonal planar structure.
Which molecule is depicted by the given ball and stick models?
BF3 - Trigonal planar with bond angle 120º.
PCI5 - Trigonal bipyramidal with bond angles 120º and 90º.
Which of the following does not show octahedral geometry?
SF4 has trigonal bipyramidal geometry. SF6, IF5, and SiF62- have octahedral geometry.
Given below is the table showing shapes of some molecules having lone pairs of electrons. Fill up the blanks left in it.
The BCI3 is a planar molecule whereas NCI3 is pyramidal, because
No lone pair ofelectrons is available in BCI3
One lone pair of electrons is available on N atom, occupies a corner in the tetrahedral arrangement. Therefore, NCI3 appears pyramidal in shape.
CF4, SF4 and XeF4 contain the following electronicstructure on their central atoms. Which one iscorrect option?
CF4−sp3 , tetrahedral but no unpaired electron.
SF4−sp3d, trigonal bipyramidal with one unpaired electron.
XeF4−sp3d2, square planar, two lone pairs of electrons.