Chemical bonding

Question 1

ionic bond factors

Answer 1

-> ionic lattice strength |qq/(r+r)| (charge over sum of radius)
greater lattice energy, stronger ionic bond, higher mp, bp

->polarity. If cation is small and highly positively charged, it attracts the electron density from
anion, distorting electron cloud. This polarisation introduced covalent character, lowering mp bp.

Question 2

Covalent bond factors

Answer 2

-effectiveness of orbital overlap
-> larger the orbital, distance between e- and nuclei increase, decrease electrostatic attraction, less effective orbital overlap.

• Bond order: triple > double > single. number of bonds: more bonds, greater electron density between nuclei, stronger electrostatic attraction between shared electrons and nuclei, stronger covalent bond

-electronegativity and polarity: more difference in EN, more polar the bond: extra electrostatic attraction between partial charges

Question 3

metallic bond factors

Answer 3

1. CHARGE of cations Directly proportional (cation higher charge = increased MB strength)
2. Ionic radius: Inversely proportional (increased MB strength = smaller ionic radius)

Question 4

Factors affecting strength of id-id

Answer 4

1. Size of electron electron cloud (ease of distortion) : larger Mr = larger cloud, dipoles more easily induced, more energy to overcome stronger id-id
2. Surface area of contact: straight chain have larger surface area of contact

Question 5

3 atoms that can have hydrogen bonding (IMF)

Answer 5

N, O, F
* protonic H / lone pair

Question 6

Factors that affect hydrogen bonding strength

Answer 6

1. Different number of H-bonds: more protonic H or lone pairs on NOF
2. Polarity of H-(NOF) bond: more polar = stronger. Order: N<O<F
3. Intra molecular H bonding may reduce the number of available H bonding sites for intermolecular bonding