Bond characteristics

Question 1

Oxidation state definition

Answer 1

The charge after ionic approximation

Question 2

Valence definition

Answer 2

The number of electrons used in bonding

Question 3

Unpaired electrons in p block species?Dont think this is right get rid of it

Answer 3

Unlikely. They will instead occupy sp hybrid orbitals and interact with other s, p or hybrid orbitals to form element bonds

Question 4

High oxidation states and electronegative species

Answer 4

Species with high oxidation states readily gain electrons. If they were bonded to species that were easily oxidised, a redox reaction would occur. This is why they tend to exist with electronegative species that are harder to oxidise

Question 5

Outline the inert pair effect

Answer 5

Gives rise to the stable forms of (usually ionic) species. Is a balance between the strength of the bonds being made, and the energy required to promote electrons to the higher oxidation state to accommodate these bonds

Question 6

Why is CCl4 stable, but PbCl4 not

Answer 6

The inter pair effect. The energy gained through the addition of two more Pb-Cl bonds does not overcome the promotion of the electronic structure

Question 7

How do electrons move during promotion during oxidation

Answer 7

In pairs and so that the overall number of electrons is even

Question 8

Shielding effects of 3d electrons

Answer 8

3d electrons shield the nucleus poorly and so, 4p elements have larger than expected effective nuclear charge

Question 9

Sensible values for bond enthalpies

Answer 9

100-300 kJmol-1

Question 10

Typical trends in bond strength across periods

Answer 10

Not much change across rows at all with one major excpetion

Question 11

Homonuclear bond strengths across period 1

Answer 11

Decrease quite significantly across the row. In groups 13 and 14, there are no lone pairs during A-A bonding. When there are lone pairs on the small atoms of period 1, there is repulsion between the two which weakens the A-A bond. These lone pairs occupy pi* orbitals

Question 12

Trend in orbital energy down groups

Answer 12

Orbital energy decreases down groups. Those in the first row are higher in energy than the second etc

Question 13

When can we assume that the electronegativity of two bonded atoms A-B are similar

Answer 13

when 2 A-B is almost equal to A-A + B-B

Question 14

Trends down groups of multiple bond strength

Answer 14

Multiple bond strength decreases down groups. As atoms increase in size, overlap between orbitals weakens weakening the pi interactions

Question 15

Typical coordination numbers of atoms

Answer 15

First row largely exceeds 4. CN of 6-7 possible for larger atoms