Answer
The fluorine has seven electrons in its outermost shell and sodium atom has one electron in its outermost shell.The sodium donates one electron completely to the fluorine atom. This means one pair of electrons is shared between the fluorine and sodium atoms. This means a single bond is formed between sodium and a fluorine atom. The bond formed by the complete transfer of an electron to another atom in a molecule is called an ionic bond.
Work Step by Step
The fluorine ($F$) is located in the highlighted box on the partial periodic table.
The fluorine, oxygen ($O$), hydrogen ($H$), and sodium ($Na$) are placed in the following order on the basis of their relative electronegativity: $F>O>H>Na$ . There will be one bond when fluorine reacts with sodium and the bond will be ionic.