General aspects of the p-block-Big Daddy Petr

Question 1

What are the maximum CN for:
2nd period:A
3rd period:B
(3)4-6th period:C
What can occur that allows higher CN?
What causes this to arise?

Answer 1

A=4
B=6
C=7-8
Hypervalency
Large fuck off radii

Question 2

Define Lewis acid and base.

Answer 2

Lewis acid=EP acceptor

Lewis base=EP donor

Question 3

What should you consider when look at whether something is a LA/LB ?

Answer 3

That it does not exceed its maximum CN.

Question 4

For the general formula SiX4, which is the stronger LA; SiF4 or SiI4.
Why?

Answer 4

SiF4
As it has the greatest electron withdrawing power, so moving electrons away from Si, allowing it to accept an EP much more easily.

Question 5

True/false, PH3 is stronger than NH3 as a LB. Why?

Answer 5

False as the LP in NH3 lies in an sp3 orbital, whilst in PH3 in an s-orbital, so less available.

Question 6

What is an allotrope and give an example?

Answer 6

Different physical form of the same element.

Graphite vs graphene vs diamond vs coal

Question 7

8S –> 4S2
8S–>S8
Which is more favoured and why? How does this differ with O?

Answer 7

S8 as is more thermodynamically stable.

O=O is more thermodynamically stable than O-O

Question 8

More pi bonds are present down a group, Why?

Answer 8

Lower group elements have larger/diffuse orbitals that have poorer overlap and therefore weaker bonds, mainly pi bonds.

Question 9

True/false, pi bond strength is more distance sensitive than sigma bond strength

Answer 9

True

Question 10

For group 13-16, describe the effects of the inert pair effect.

Answer 10

Heavier groups favour an oxidation state of 2 lower than the group number(maximum), and therefore are weaker reducing agents.

Question 11

Which bond enthalpy is greater:

EX(n-2) +X2 EXn

Answer 11

EX(n-2)

Question 12

True/False, s>p>d>f in terms of penetration
What does this mean for an ns electron?
How does this change going down a group?
What does this contraction cause?

Answer 12

True
Pulled closer to nucleus(contracted)
Becomes more pronounced down a group
The ns are more excluded from bonding, and become LP in character, causing the famous IP effect

Question 13

The covalent radius of Al and Ga are the same. Why?

Answer 13

Ga starts to fill up the 3d, which are quite diffuse, so cannot shield each other effectively, causing the 4s and 4p to feel a greater nuclear charge, being contracted!

Question 14

In Ti are close in radius. Why?(in terms of f-block contraction)

Answer 14

Poor shielding from f-orbitals and d-orbitals as very diffuse, so p-orbitals highly contracted, causing this greater Zeff

Question 15

Ti has a higher Ei than In, why? (In terms of relativistic effects)

Answer 15

When an electron is close to a heavy nucleus, its velocity increases which causes a relative increase in mass and therefore binding energy(the energy that holds nucleus together). This causes a contraction in that specific orbital, causing an electron to spend more time in s than f for example, and therefore cause high ionisation energies in period 6.

Question 16

What is another name for the contractions?

Answer 16

Alternation effect.