*** EK Chemistry: Which of the following does not exist? ***

[Lunasly]

Q. Which of the following does not exist? Please provide an explanation about which one if right and why the rest are wrong!

A) IBr
B) UF6
C) OF5
D) NaLiCO3

Answer: C (highlight)

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[Sterling Archer]

Q. Which of the following does not exist? Please provide an explanation about which one if right and why the rest are wrong!

A) IBr
B) UF6
C) OF5
D) NaLiCO3

Answer: C (highlight)

A) IBr is possible because it is similar to other diatomic forms of halogens.
B) UF6 is possible because atoms with an atomic number larger than sodium's can partake in valence shell expansion. Basically, atoms in period 3 or greater can violate the octet rule.
C) For reasons explained for B, OF5 CAN NOT exist because O can't partake in valence shell expansion. Specifically, the energy level difference between 2p (orbital for oxygen's valence electrons) and 3d is too great, so O can't partake in D-orbital expansion.
D). The carbonate ion has a charge of -2, so it can complex with either one M2+ ion or TWO M1+ ions (where M is a metal).

 

[Testosterone]

As a general rule. Period 2 elements cannot have an expanded octet.