chapter 3: chem bonding ⚗️

Question 1

what is ionic bond

Answer 1

it is the electrostatic attraction between the oppositely charged ions

Question 2

definition of coordination number

Answer 2

number of ions that immediately surround an ion of the opposite charge within a crystal lattice

Question 3

what are the factors affecting the magnitude of lattice energy

Answer 3

1. product of ionic charge ➡️ larger ionic charge, larger the magnitude of lattice energy
2. sum of ionic radii ➡️ larger the sum, smaller the magnitude of lattice energy

Question 4

why are ionic compounds insoluble in water

Answer 4

energy released during formation of ion-dipole interaction between ions and water molecules is not enough to overcome energy needed to break strong electrostatic attraction between oppositely charged ions

Question 5

what is a covalent bond

Answer 5

strong electrostatic attraction between the positively charged nuclei of atoms and their shared pair of electrons

Question 6

what is a sigma bond

Answer 6

formed when atomic orbitals overlap head on

Question 7

what is a pi bond

Answer 7

formed when atomic orbitals overlap side on

Question 8

what ar the factors affecting covalent bond energies

Answer 8

1. bond order (triple bond > double bond > single bond)
2. bond length (shorter bonds are stronger)
3. bond polarity

Question 9

why is a pi bond weaker than a sigma bond

Answer 9

due to less effective overlap between orbitals

Question 10

definition of bond length

Answer 10

inter nuclear distance between the two bonding atoms

Question 11

why are period 3 central atoms able to accommodate additional electrons

Answer 11

it has empty and energetically accessible d orbitals to accommodate the extra electrons

Question 12

definition of dative bond

Answer 12

a covalent bond in which both electrons of the shared pair come from one of the two bonded atoms

Question 13

what are the 2 principles of VSEPR theory

Answer 13

1. electron pairs in the valence shell of a central atom will arrange themselves in space as far as possible from each other to minimise repulsion
2. lone pair-lone pair repulsion > lone pair-bond pair repulsion > bond pair-bond pair repulsion

Question 14

list out the shape and bond angles

Answer 14

refer to notes

Question 15

what are the factors affecting degree of covalent character

Answer 15

1. polarising power of cation ➡️ higher the charge, smaller the cationic radius, higher the charge density, higher the polarising power
2. polarisibility of anion ➡️ higher the charge, larger the anionic radius, more polarisable

Question 16

bonding tends to be covalent if _____

Answer 16

1. cation is small
2. anion is large
3. charges on both ions are high

Question 17

definition of bond polarity

Answer 17

property of shared pair of electrons being closer to one atom than the other in a covalent bond

Question 18

what are the factors affecting strength of id-id attraction

Answer 18

1. greater number of electrons per molecule, more polarisable the electron cloud, stronger id-id
2. larger surface area of molecule, greater area of contact, stronger id-id
3. packing of molecules ➡️ trans isomer higher mpt. ➡️ more elongated, larger surface area of contact

Question 19

what are the factors affecting pd-pd

Answer 19

1. magnitude of net dipole moment

Question 20

what are the conditions of hydrogen bonding

Answer 20

1. H atom bonded to F, O or N atom on one molecules
2. lone pair of electron on F, O or N atoms of the neighbouring molecules

Question 21

what are the factors affecting strength of hydrogen bonding

Answer 21

1. average number of hydrogen bonds per molecule ➡️ greater, more extensive hydrogen bonds
2. difference in electronegativity

Question 22

why do you think SF6 exists and not SCl6

Answer 22

expansion of octet is a,so limited by atom’s size ➡️ 6 F atoms can fit around S atom, but not larger Cl atoms due to steric hindrance