10. Heteronuclear diatomics

Question 1

What are heteronuclear diatoms?

Answer 1

Two atoms molecules where the two atoms are of different elements

Question 2

What is the primary difference between homonuclear and heteronuclear diatomic MO?

Answer 2

In homonuclear - AO are of the same E

In heteronucelar molecules AO are of different E

Therefore now e in MO are chared unequally (nearer to atom 2) -> polar bonds

Question 3

When does MO have significant character of AO?

Answer 3

When MO E is very close to AO

Question 4

How to know if Li 2s or H 1s is higher in E? Why is the shape of LiH not spherical?

Answer 4

• H has higher EN value than Li -> 1s lower in E and 2s higher in E

The more electronegative - the lower the valence e are

• Although both 2s and 1s AO are spherical - MO is not spherical due to EN differences
• Bonding orbital drawn to H but antibonding to Li because of MO E proximity to AO of each atom
• Lithium hydride - ‘hydride’ suggests ionic interaction - e drawn to H (in hydrogen fluoride - e closer to F -> fluoride)

Question 5

Explain in-phase and out-of-phase orbital combinations in heteronuclear diatomic molecules

Answer 5

a) constrcutive interference
b) destrcutive interefernce

Question 6

What are non bonding interactions?

Answer 6

Directly cancel each other due to phase differences - no interaction

Question 7

What is the MO of HF?

Answer 7

• 2 2p orbitals have non-bonding interactions with 1s due to phases - do not change from AO to MO - 2p -> 1π
• 1 2p orbitals interacts
• when calculating bond oder ignore the non-bonding orbitals

Question 8

What is the MO energy diagram for CO?

Answer 8

• similarity to which molecule in terms of VE?

in N₂ 10VE → in CO 10VE => MO arrangement likewise

Question 9

What are the possible overlaps of in-phase and out-of-phase AO in MO?

Answer 9

Question 10

Objectives for revision

Answer 10

Objectives for revision