Question

How many Al atoms thick is the aluminum foil if it is 0.00157cm thick.

1 Al atom = 286pm

Convert pm to m
286pm = 2.86*10^-10m

Convert m to cm
2.86*10^-10m = 2.9*10^-8cm

Divide aluminum thickness and Al atom thickness
1.57*10^-3 / 2.9*10^-10 = 54138

So the aluminum foil is 54138 Al atoms thick?

Am I correct? If not please correct me!

Thank you very much.

Answer 1

1 Al atom = 286pm

Convert pm to m
286pm = 2.86*10^-10m

agreed

Convert cm to m
0.00157 cm

0.00157 cm/10^2 cm m^-1

=0.0000157 m

Divide aluminum thickness and Al atom thickness
1.57*10^-5 m / 2.9*10^-10 m = 54138 atoms

so looks OK. It is a good idea to keep units in calculations so you can make sure that the units cancel.