Question

What do you mean by saying "1000 atoms thick"?

Answer 1

When Rutherford conducted his experiments, the concepts of molarity , Avogadro no. was already discovered and widely accepted in chemistry. The internal structure of the atom however was disputable. So Rutherford must have calculated the weight of gold foil... By knowing the mass no. of gold calculated the no. of atoms in the foil( check concepts of molarity and Avogadro no.) then considered that atoms are uniformly distributed.... Thus divided that number by area of foil to find that the foil is a few thousand atoms thick

Consider the mass of foil = 1.2*10^-17 gram

Mass no. of gold= 200(approx)

So 200g of gold has 6*10^23 atoms

So the foil has 1000 atoms

If the area of foil is 1 sq. unit

Then the foil is 1000 atoms thick...

Hope this answers your question!!!