Answer:
Please check the attached file
Explanation:
Sodium is present in group one. It has one valence electron. It is alkali metal. All alkali metal form salt when react with halogens.
Sodium need to lose one electron to get stable. All halogens have seven valence electrons they need only one electron to get stable electronic configuration.
When alkali metals such as sodium react with halogen fluorine it loses its one valence electron which is accepted by fluorine and ionic bond is formed. The compound formed is called sodium fluoride.
In cross and dot diagram electrons of one atom are shown as dots while other atom shown as cross to distinguish.
Please check attached file for electron dot diagram.