By: Giovanni & Brendan
Sodium has a +1 charge due to having 1 valence electron. It is more easier to lose 1 valence electron than to gain 7. Since this compound has 2 Sodiums, it will contain 2 valence electrons to share with the Sulfur element.
Sulfur has a -2 charge due to having 6 valence electrons. Thus making it easier to gain 2 more valence electrons.
2 Sodium elements with a +1 charge are needed because 1 Sulfur element has a -2 charge. Therefore, making it easier to transfer the amount of valence electrons needed for Sulfur.
2 Sodium elements are needed to attract a Sulfur element, since Sodium will be sharing at least 1 valence electron. Filling up the amount of valence electron missing for Sulfur (2 valence electrons needed), the compound element formula would be written as Na2S.