What is the ionic formula for sodium chloride?

NaCl
Sodium is an Alkaline Metal in the first column of . This means that Sodium has 1 valence electron it readily gives away in order to seek the stability of the octet. This makes Sodium a ##Na^(+1)## cation.
Chlorine is a Halogen in the 17th column or ##p^5## group.
Chlorine has 7 . It needs one electron to make it stable at 8 electrons in its valence shells. This makes chlorine a ##Cl^(−1 )## anion.
Ionic bonds form when the charges between the metal cation and non-metal anion are equal and opposite. This means that one ##Cl^(−1)## anion will balance with one ##Na^(+2)## cation.
This makes the formula for calcium chloride, ##NaCl##.