T1- p Block LP2

Question 1

What is trend for covalent radii in periodic table?

Answer 1

It decreases from left to right and from bottom to top.

Question 2

What is Slater’s rule?

Answer 2

The outermost electrons feel a nuclear charge which is less than the actual nuclear charge, because of shielding effects from othermost electrons.

Question 3

How to calculate effective nuclear charge?

Answer 3

Z*=Z-s, where Z is an actual nuclear charge, s-shielding constant.

Question 4

What are the groupings when estimating shielding constant?

Answer 4

(1s) (2s,2p) (3s,3p) (3d) (4s,4p) (4d) (5s,5p) etc.

Question 5

How much s contribute for each electron that has the same principle quantum number in the same (ns,np) (nd) d=group?

Answer 5

s=0.35

Question 6

How much s contribute for each electron in the (n-1) shell?

Answer 6

s=0.85

Question 7

How much s contribute for each electron in the (n-2) shell or lower?

Answer 7

s=1.00

Question 8

What is the difference in estimating shielding constant when looking at an electron in an nd or nf orbital?

Answer 8

Each of the other electrons in the (nd,nf) group contributes 0.35, but the rest of electrons in lower groups contributes 1.00.

Question 9

What is the trend of effective nuclear charge in periodic table?

Answer 9

It increases from left to right and from top to bottom.

Question 10

What is the trend of ionisation in periodic table?

Answer 10

It decreases from left to right and from top to bottom.

Question 11

What is covalent radii?

Answer 11

A covalemt radius is defined as half the length of a symmetrical homonuclear element bond.

Question 12

What is cation?

Answer 12

A poistively charged ion.

Question 13

What is anion?

Answer 13

A negatively charged ion.

Question 14

What is general trend of covalent radii and why?

Answer 14

It increases going down a group as valence electrons are further from the nucleus, and it decreases from left to right as effective nuclear charge increases.

Question 15

Why within a particular group, highest occupied orbital energies increase from top to bottom and the s-p separation decreases?

Answer 15

Becaues we have higher principal quantum shells so electrons further away from nucleus.

Question 16

Why Ga and Ge does not follow s-p separation decrease trend?

Answer 16

It is because 4p row is immediately proceded by full 3d row which lowers the energy of the s orbital.

Question 17

Why s and p energies decrease from left to right?

Answer 17

It is because efective nuclear charge increases for both, but s has better penetration compared to p so s decreases more.

Question 18

Why 4s orbital for As, Se, Be, and Kr are lower than expected?

Answer 18

Because effective nuclear charge increases from 3rd row it has strong effects on 4s.

Question 19

Why wlwctrons in p orbitals are less stable and higher in energy than s?

Answer 19

This is because the s orbital penetrates closer to the nucleus and experiences a greater stabilising effect from its positive charge.

Question 20

What is inner pair effect?

Answer 20

The tendency of the electrons in the outermost atomic s orbital to remain unionised or unshared in compounds of the group 13-16 elements.

Question 21

Waht is the order of group 13 stability of +1 state?

Answer 21

Al < Ga < In < Tl

Question 22

That is the order of group 14 stability of +2 state?

Answer 22

Si < Ge < Sn < Pb

Question 23

Why inner pair effect occur?

Answer 23

It is because strength of covalent bonds decreases down a group due to poor orbital overlap and bond enthalpy does not offset the rehybridisation energy cost. For example, for Pb to rearange electrons to sp3 type of configuration would cost more energy that the amount of energy contained in, for example, Pb-C bond.

Question 24

What are relativistic effects?

Answer 24

The heavier the elements the faster the outer electrons go.

Objects moving near the speed of light gain mass.

Question 25

What is direct relativistic orbital contraction?

Answer 25

When electron reaches a high percentage of speed of light it gain mass. So some orbitals contract and its energy is lowered.

Question 26

Which orbitals experience direct relativistic orbital contraction?

Answer 26

s- they stabilised the most because they have best penetration and p- they stabilised less as they have poorer penetration.

Question 27

Which orbitals experience indirect relativistic expansion?

Answer 27

d and f as a result of poor penetration and the contraction of s and p leaves them more shielded and less affected by effective nuclear charge.