I need a AP Chem question answered for me.?

Question

One atomic mass unit has a mass of 1.6605402 x 10^-24 g. Calculate the mass, in grams, of one atom of magnesium. What is the Mass of one atom of iron, expressed in grams? Use these two answers to determine how many atoms of Mg are in 24.305 g of magnesium and how many atoms of FE are in 55.847 g of iron. Compare your answers. How many atoms do you think would be in 40.078 g of calcium? What conclusions can you draw from the results of these calculations?

that is one problem in my ap chem book that i can not figure out. any help please. and if you could when you solve the equations or whatever to put it detailed in the answer w/ it. thank you much.

if you help i will make you best answer and even make fake questions to make you best answer.

i just really need help!!!

Answer 1

Well the grams given for Mg and Fe are their AtWts! So there had better be 1 Avogadro's number (6.022xE23) for each.

Of course, the object is to show that multiplying the "mass unit" time the number of protons and neutrons does not give the same answer.

One atom of Mg = (12+12)*1.6605402E-24

Mg: 24.3405/[(12 p + 12 n)* 1.6605402E-24] = 7.138E23 atoms in the specification (24.3405 g)

Others are similar calcs.

The value cited is approximately that of D: 2.0136/6.022E23/(1p+1n) = 1.6719E-24

AVERAGE atomic mass IS NOT CONSTANT over the entire periodic chart!