Question

4- Atomic number of element X is 17, Find the group number of X

Answer 1

1. For s-block elements , group number is equal to the number of valence electrons.
2. For p-block elements ,group number is equal to 10+number of electrons electrons in the Valence shell .
3. For d-block elements group number is equal to the number of electrons in a (n-1) d subshell + the number of electrons in Valence shell .

Now let use consider the Periodic Table, it is certain that we will try and answer to the points following the rules of the PD elements.

If the element X has At. Number = 17, then its valence can be written as 2 , 8 , 7.

It has 7 electrons in its outer most orbit (Valence shell).

Now getting to the other parts of the question,

(a) Physical state = It would have the same physical state as that of Chlorine elements (which has the same electronic configuration and atomic number). The element X will be mostly in gaseous form when at normal state (temperature). The color cannot certainly be the same, but it may be slight yellowish in color. At lower temperature, this element would certain be in the liquid form. This would be at -30 t0 -34 Deg. C. The Element would in fact be much heavier as compared to air.

(b) Name of element = Now as the element is having Atomic Number equal to 17, so it is certain that it would be named as Chlorine.

(c) Formula of its compound with hydrogen = On reacting with Hydrogen, it is certain that this element would acid. HCl is an example of its compound with hydrogen.

(d) Metal or non-metal = The element X would in fact belong to the Halogen group, which is non metal. It would have all properties that are similar to Other Halogens in Group 17.

(e) Formula of its molecule = Now in its stable state, Chlorine gas would exist as a combination of two atoms of chlorine attached by single bond. So its molecular formula of Chlorine gas is Cl2. (Cl – Cl).  

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