For this problem two generic elements "X" and "Z" are going to combine to form an ionic compound. If the element X has 2 valence electrons and the element Z has 6 valence electrons, what is the chemical formula for the lonic compound they would create?
а) X2Z2
b) X6Z2
c) XZ6
d) XZ

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.