Respuesta :
Answer:
K2X
Explanation:
Valency can be defined as the combining power of an element. It is the valency that dictates the value an element will have when writing a chemical formula for its compound.
MgX is a compound of magnesium and an element X. The valency of magnesium in most of its compound is +2. Now for the 2 to have been absent in the chemical formula, this shows that the element X itself have a valency if -2 for the valencies of both to have canceled out.
Now considering the element potassium, it is an alkaline metal belonging to group 1 of the periodic table. Hence, it is expected that it has a valency of +1
Forming a compound with element X means there would be an exchange of valencies between the two. We have established that x has a valency of -2. The formula of the compound thus formed by exchanging the valencies of both element would be K2X
The most likely formula for the compound formed between potassium and element X would be [tex]K_2X[/tex].
Magnesium reacts with X to form MgX.
Magnesium has 2 valence electrons ([tex]Mg^2^+[/tex]), in order to form MgX with the element X, it means X must have the capacity to accept the 2 valence electrons from Mg. Thus, X would carry a deficit of 2 electrons in its valence shell ([tex]X^2^-[/tex]).
Potassium has one valence electron ([tex]K^+[/tex]). In order for [tex]X^2^-[/tex] to react with potassium, 2 atoms of potassium would be needed to donate their electrons each to [tex]X^2^-[/tex] in order for X to become stable. Thus
2[tex]K^+[/tex] + [tex]X^2^-[/tex] ---> [tex]K_2X[/tex]
More on forming compounds from atoms can be found here: https://brainly.com/question/1285376
