Question

How many atoms of phosphorus are represented in 2Ca3(PO4)2?

Answer 1

In order for you calculate the number of atoms of an element in a given compound, all you need to do first is to determine the number of molecules of that element in that given compound.

From there it is universally known  that 1 molecule contains  6.02 x 10²³ atoms.

So 2Ca₃(PO₄)₂ contains 2 moles of phosphorus per mole as you can see, and there are 2 moles present. Hence there are a total of 4 moles of phosphorus present in the compound.

But we know that each mole contains 6.02 x 10²³ atoms.

Therefore the atoms of phosphorus are:

6.02 x 10²³ x 4 = 2.408 x 10²⁴ atoms