Uol Ch1200 (General Chemistry) - Topic B, Q.

Front 1

What is a Chemical Bond?

Back 1

A chemical bond is an attractive force that holds groups of atoms together ---> lower energy state. Carried out by electrostatic attraction of ions or degree of sharing of e⁻.

Front 2

Describe Covalent Bonding?

Back 2

Covalent bonding is the overlap of atomic orbitals between atoms. Which there is symmetry around the bond axis and are of similar energy.

Front 3

Describe Ionic Bonding?

Back 3

Ionic bonding occurs from the electrostatic attraction between cation and anions.

Front 4

Describe Metallic Bonding?

Back 4

Type of chemical bonding that results from attractions of a lattice of metal cations and delocalized e⁻.

Front 5

What creates a Polar Bond?

Back 5

The unequal distribution of e⁻ density at particular regions on a molecule - permanent dipole moments (partial +δ and -δ charges).

Front 6

Describe a Dative Covalent Bond?

Back 6

When a pair of e⁻ is donated by the same atom in a molecule.

Front 7

Define a Lewis acid?

Back 7

e⁻ pair acceptor

Front 8

Define a Lewis base?

Back 8

e⁻ pair donor

Front 9

For BH₃PMe₃ which component is the Lewis acid and the Lewis base?

Back 9

•Lewis acid: BH₃

•Lewis base: PMe₃

Front 10

Name the type of bonding found for MgCl2?

Back 10

Ionic bonding

Front 11

How many val. e⁻ does SF6 have and why is it known as a hypervalent molecule?

Back 11

•There is a share of 12 val. e⁻ centred around the S atom.

•Hypervalent due to the accommodation of the unfilled d-orbital, which leads to an expanded octet.

Front 12

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 12

•Orbital overlap = s orbitals

•Interaction = constructive

•Bond = σ bonding

Front 13

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 13

•Orbital overlap = s orbitals

•Interaction = deconstructive

•Bond = σ* anti-bonding

Front 14

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 14

•Orbital overlap = s and pₓ orbitals

•Interaction = constructive

•Bond = σ bonding

Front 15

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 15

•Orbital overlap = s and pₓ orbitals

•Interaction = deconstructive

•Bond = σ*anti-bonding

Front 16

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 16

•Orbital overlap = pₓ and pₓ

•Interaction = constructive

•Bond = σ bonding

Front 17

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 17

•Orbital overlap = pₓand pₓ orbitals

•Interaction = deconstructive

•Bond = σ* anti-bonding

Front 18

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 18

•Orbital overlap = pᵧ and pᵧ orbitals

•Interaction = constructive

•Bond = π bonding

Front 19

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 19

•Orbital overlap = pᵧ and pᵧ orbitals

•Interaction = deconstructive

•Bond = π* anti-bonding

Front 20

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 20

•Orbital overlap = dₓᵧ and dₓᵧ orbitals

•Interaction = constructive

•Bond = π bonding

Front 21

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 21

•Orbital overlap = dₓᵧ and dₓᵧ orbitals

•Interaction = deconstructive

•Bond = π* anti-bonding

Front 22

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 22

•Orbital overlap = dₓᵧ and pᵧ orbitals

•Interaction = constructive

•Bond = π anti-bonding

Front 23

Describe the MO in terms of:

•Orbital overlap

•Interaction

•Bonding

Back 23

•Orbital overlap = dₓᵧ and pᵧ orbitals

•Interaction = deconstructive

•Bond = π* anti-bonding

Front 24

Explain why overlap is not possible with these examples.

Back 24

•Lack of symmetry between atomic orbitals with respect to the bond axis.

•σ and π unable to overlap with each other.

•Orbitals are overlapping in-phase and out of phase.

Front 25

Deduce the geometry of BeCl₂ using "VESPRT".

Including:

• Shape

• Bond angle

• Stating any lone pairs

Back 25

Be

•Central atom: Be

•e⁻ configuration: [He]2s²

•Be contributes 2 val.

e⁻

•Cl (x2) contributes 2 val. e⁻

•So 4 val. e⁻, i.e. only 2 bonding pairs, 0 lone pairs.

• 2 e⁻ bonding pairs

indicates a linear arrangement.

Therefore the shape is linear (180°).

Front 26

Using "VESPRT" deduce the geometry of PCl₅

Including:

• Shape

• Bond angle

• Stating any lone pairs

Back 26

P

•Central Atom: P

•e⁻ configuration:[Ne]3s²3p³

•P contributes 5 val. e⁻

•Cl (x5) contributes 5 val. e⁻

•10 val. e⁻, i.e. 5 pairs.

•5 bonding pairs. Therefore shape is trigonal bipyramidal (120° equatorial, 90° axial)

Front 27

Use "VESPRT" deduce the geometry of SF₄

Including:

• Shape

• Bond angle

• Stating any lone pairs

Back 27

S

•Central Atom S

•e⁻ configuration:

[Ne]3s2 3p4

•S contributes 6 val. e⁻

•F (x4) contributes 4 val. e⁻

•In total 10 val. e⁻, i.e. 5 e⁻pairs

•4 bond pairs and 1 lone pair. So arrangement is a distorted trigonal bipyramid (<120°equatorial ,90° axial) with the lone pair on the equatorial site (most stable form as reduces number of lp-lp and bp-lp interactions).

Front 28

Which combinations of AO make up a MO?

Back 28

• In-phase combination (constructive interection)

• Out-of-phase combination (destructive interection)

Front 29

Complete the MO diagram of Li₂ applying Hund’s rule (hint: diagram).

Back 29

Note:

Following Aufbau principle, lowest E. lvls. are filled first.

Meanwhile Hund's rule, each lvl is filled in spin parallel before pairing.

Front 30

What is the BO of Li₂ (hint: diagram)

Back 30

BO of Li₂:

BO = (ΣBonding e⁻ - ΣAnti bonding e⁻) /2

(4-2)/2 = 1