Question

Write down the characteristics of the element having atomic number $17$ .
Electronic configuration _______________
Period number ________________
Group number __________________
Element family __________________
Number of valence electrons ______________
Valency _______________
Metal or non- metal __________________

Answer 1

The atomic number of any element represents the number of protons present in the atom or the number of electrons present in the ground state of an atom. In the periodic table, the element which has an atomic number equal to $17$ is chlorine which lies in the group of halogens and has a total of seven valence electrons in its outermost shell.

Complete step by step answer:
As we know that the atomic number $17$ is represented by chlorine in the periodic table, so let us discuss the various characteristics of chlorine.
(i) Electronic configuration: The representation of the filling of electrons in the atomic orbitals in an increasing order of energy is known as electronic configuration. The electronic configuration of the element with atomic number $17$ will be:
$C{l_{17}} = 1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$
(ii) Period number: The period number is determined with the help of the number of outermost shells or simply the highest shell number. From the electronic configuration mentioned above, we find that:
Period number = 3
(iii) Group number: The group number for p- block elements is = $12 + np$ electrons
The $p -$ orbital has five electrons.
Thus, group number = $12 + 5 = 17$
(iv) Element family: The family to which the chlorine belongs is the Halogen family.
(v) Number of valence electrons: The number of electrons present in the outermost shell of an atom is known as the valence electrons. Hence, number of valence electrons in chlorine = 7
(vi) Valency: In order to achieve the nearest noble gas configuration, chlorine requires an extra electron. Thus, the valency of chlorine is = $- 1$
But the range of oxidation states of chlorine is $- 1$ to $+ 7$ .
(vii) Metal or non- metal: In order to attain a stable electronic configuration, chlorine requires an extra electron. Hence, it acts as a non- metal.

Note: Chlorine is an element of the periodic table with the symbol $Cl$ and atomic number $17$ . The second element in the halogen series, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine appears as a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent.