Question

How do the atoms Sodium and Fluorine combine in $NaF$?

• A. Covalent way
• B. Electrovalent way
• C. Ionic way
• D. None of these

Answer 1

Answer: (B), (C)

Ionic way
Electrovalent way

Sodium has $11$ electrons in it, which can be written as $2,8,1$. Thus we see that Sodium has $1$ electron in its outermost orbit that is $Na$ has $one$ valence electron. Sodium wants to lose this $one$ valence electron to complete its octet by having $8$ electrons in its outermost orbit.
On the other hand, Fluorine has $9$ electrons in it, which can be written as $2,7$. Thus Fluorine has $7$ electrons in its outermost orbit and it needs $one$ more electron to complete its octet by having $8$ electrons in its outermost orbit.
Thus, we find that Sodium wants to lose $one$ electron, whereas, Fluorine wants to gain $one$ electron to complete their octet. They achieve this when Sodium transfers its valence electron from itself to Fluorine so that $Na$ gains $+1$ charge and $F$ gains $-1$ charge.
An ionic bond is formed between atoms when one atom transfers its electrons from itself to its neighboring atom. Here Sodium transfers its one electron from itself to Fluorine and thus an ionic bond is formed between them. An ionic bond is also known as electrovalent bond. Thus $NaF$ is an ionic compound or an electrovalent compound.