Question

1a. Write out the valence or noble gas electron configuration for 49-In, and 81-Tl

2a. Write out the ionic form for 49-In.

3a. Period 6 heavy metals tend to lose their p-electrons, but retain their s-electrons, this is called the “inert pairing effect.” Write out the noble gas electron configuration for 81-Tl and what would the oxidation number of Tl be in this case?

Answer 1

1a. Electron configuration for 49-In: [Kr]4d105s25p1

Electron configuration for 81-Tl:
[Xe]4f¹⁴5d¹⁰6s²6p¹

2a. Ionic charge:
Where a main-group metal tends to lose elections forming a cation with the same number of elections as the nearest noble gas, the number of electrons lost is equal to the group number.
Ionice charge on 49-In = +3 (ln³+).

3a. Noble gas electron configuration for 81-Tl = [Xe]
The only Oxidation state of 81-Tl that exists is = +1

Tl family has a +3 or +1 oxidation state, because thallium is heavy, it has a greater stability in the +1 oxidation state , this is inert pair effect. Therefore, it is found more commonly in its +1 oxidation state.

The elements generally follow periodic trends except for certain Tl deviations:
Atomic radius increases down the group (Tl has the largest atomic radius.)
Electrode potential increases down the group (reactivity decreases down the group).
Ionization Energy decreases going down the group (because the electrons are farther from the core and therefore are easier to remove; Tl does not fit this trend).