You have been working to develop a new fictitious compound in the lab. determine the amount in units of moles [mol] of 20 grams [g] of this compound. the compound has the formula: upper x 2 upper y 2 upper z 7, where the components are x, amu equals 47; y, amuequals42; z, amu equals 16.

From the chemical formula the total mass of the compound can be determined. The mass of the 1 mole of the compound is its molar mass. The atom by which the molecule is generated, the mass of these atoms are expressed in terms of amu or atomic unit mass, but after formation of a molecule in a particular ratio the mass of each of the atom becomes the total molecular weight of the generated molecule. In this case the molecule posses three atoms X, Y and Z which are in a ratio of 2:2:7. Thus the chemical formula of the compound can be written as .

So the total mass of the compound in amu is {(2×47)+(2×42)+(7×16)} = {94+84+112}=290 amu.

Thus 1 mole of the compound contains 290 amu or 290 g  by mass.

Henceforth 20 gram of the compound is equivalent to  (20/290) = 0.068 mole.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.