Question

Which of the following commonly forms ionic compounds as a $-1$ anion?

• A. $C$
• B. $N$
• C. $O$
• D. $F$
• E. $Ne$

Answer 1

Answer: (D)

$F$

Fluorine being a halogen is present in Group 17 and has $7$ electrons in its outermost orbit. It needs only $1$ more electron to complete its octet. So, in an ionic compound, Fluorine combines with an electropositive element like Sodium or $Na$. Thus $NaF$ is formed where $Na$ trasfers its $1$ and only valence electron to $F$, so that $Na$ obtains $+1$ charge with $1$ electron less and $F$ obtains $-1$ charge with $1$ electron more.

Thus both $Na$ and $F$ complete their octets where $F$ is the anion having $-1$ charge.

Option $D$ is the correct answer.