Question

The elements $Z=117$ and $120$ have not yet been discovered. In which family /group would you place these elements and also give the electronic configuration in each case.

Answer 1

Electronic configuration

Electronic configuration of $Z=117\&Z=120$ can be written as.

$Z=117:\left[Rn\right]5f^{14}6d^{10}7s^{2}7p^5$

$\left(2\right)Z=120;\left[Uuo\right]8s^2$ or $\left[Rn\right]5f^{14}6d^{10}7s^{2}7p^{6}8s^2$

Place of $Z=117$ and $120$ in periodic table

$\left(1\right)Z=117$ last electronic configuration is $7s^{2}7p^5$

We know, Group $13-18$ belongs to p block in periodic table.

If $p^1\to 13$

$p^2\to 14$

$p^3\to 15$

$p^4\to 16$

$p^5\to 17$

The number of periods = maximum value of $n=7$

Hence, place for $Z=117$ is ${17}^{th}$ group(Halogen family) and $7^{th}$ period.

$\left(2\right)$ For $Z=120$ last electronic configuration is $8s^2$

$\because$ we know, "group $1$ and $2$ belong to $s$ block".

If $s^1\to 1^{st}$ group (alkali metal)

$s^2\to 2^{nd}$ group (alkaline earth metal)}

The period number = maximum value of $n(=8)$

Hence , place of $Z=120:$ Group $\to 2$ (alkaline earth metal)

Period $\to 8$

Final answer: $Z=120:$ Group $\to 2$ (alkaline earth metal)

Period. $\to 8$

$Z=117:$ Group $\to 17$ (Halogens)

Period. $\to 7$