Skip to main content
Ch.22 - The Main Group Elements

Chapter 22, Problem 22.3

Which of the following elements (X) will form a covalent hydride with the formula XH3 that is a gas at room temperature? (LO 22.4)

(a) Al (b) As (c) Ba (d) Se

Verified Solution
Video duration:
0m:0s
This video solution was recommended by our tutors as helpful for the problem above.
97
views
Was this helpful?

Video transcript

All right. Hi, everyone. So this question is asking us at room temperature, which element would form a gaseous covalent hydride with the formula A two option A says gallium. Option B says beryllium, option C says sulfur and option D says nitrogen. Now recall a covalent hydride involves two nonmetals, right? Because one other non metal is going to combine with hydrogen via a covalent bond in which electrons are being shared between them. Now, the formula of the hydride itself, meaning the ratio of hydrogen to the other nonmetal depends on the group in which the other nonmetal resides in in the periodic table. No, earlier, I mentioned the fact that covalent hydride must involve two nonmetals. So therefore, I can go ahead and actually eliminate any metals that I happen to have in my answer choices. So gallium and beryllium are going to be removed for this reason. So at this point, we can compare and contrast sulfur and nitrogen to start off recall that sulfur is found in group six a of the periodic table in which it normally has six valence electrons. Now because it has six valence electrons, two more electrons are required to complete its octet. So because of this sulfur generally forms two covalent bonds with other atoms to complete its octet, which means that a hydride that contains sulfur would generally have a chemical formula of HS two or otherwise known as H two S. Now nitrogen, on the other hand, resides in group five a of the periodic table, which means that it has five valence electrons. So therefore, nitrogen generally forms three covalent bonds with other atoms to complete its octet. This means that a hydride containing nitrogen would have a chemical formula of NH three. So based on this right, we can see that it's sulfur that would form a hydride, a gaseous covalent hydride with the formula of HS two because sulfur is capable of forming two covalent bonds due to the fact that it already has six valent electrons. So our answer here is going to be option c in the multiple choice. And with that being said, thank you so very much for watching. And I hope you found this helpful.