Question

An element having atomic number $50$. Find its group number and periodic numbers.

Answer 1

-In order to identify the periods to which an element belongs we must know how many electrons that element has and consequently the electronic configuration can give us an idea about the position of that element in the periodic table.
-The atomic number of an element provides information about the total number of electrons contained by that atom as well as, how many electrons are present in the outermost orbital.

Complete step by step answer:
The horizontal rows in a periodic table are termed as Periods and the vertical columns are termed as Groups. There are $7$ periods and $18$ groups present in the Periodic Table. The atomic number of an element increases as we move down the group as well as, across a period.
We know that the element which has atomic number $50$, is tin and it has a configuration $\left[ Kr \right]4{{d}^{10}}5{{s}^{2}}5{{p}^{2}}$, as we can see from the configuration, the last electron entered in the $p$ orbital, hence it is a $p$ block element.
The period of an element is the principal quantum number which is the number which is assigned to each electron which is present in an atom which describes the state of the electron. So it is $5$ in this case. Hence the period number is $5$.
For the prediction of the group number, the number of electrons in the penultimate shell and the valence shell are considered. So it would be,
$2+2=4$
So, now we can see that the number of electrons in the penultimate shell and the valence shell is $4$, so as a result the group number of the considered element would be four.
Hence, the group number is four and period number is five, of the element which has atomic number $50$.

Note: The group number of an element is the number of electrons present in the penultimate as well as the valence shell.
The period number of an element is simply the value of the principal quantum number of the valence shell. Principle quantum number is one of the four quantum numbers which are used to predict the exact position and spin of an electron, inside an atom.