The following two elements react to form an ionic compound: 1) Na (Z = 11) 2) Se (Z = 34) If the compound that is formed by the reaction of these two elements c

Question

Answer please i want the answer

 

Answer 1

Sodium is in group 1, and has 1 valence electron.  Selenium is in group 6 and has 6 valence electrons.  Sodium is a non metal, and selenium is a metal, thus they form an ionic bond.  It will take 2 Na and 1 selenium to make sodium selenide, 

Na₂Se.  Each mole of Na2Se contains 2 moles Na and 1 mole Se or each formula unit of Na2Se has 2 Na ions and 1 Se ion.

So, the number of Se ions is 1/2 the number of Na ions.

1.79x10⁴⁴/2 = 8.95x10⁴³ Se ions