# If I have a chart that claims that the Atomic radius of Rubidium is 248 picometers cubed, how can I calculate how many Rubidium atoms span the length of 1.00 centimeter (Assume that the Rubidium atoms are touching each other) ?

##2.02 * 10^(7)”atoms of Rb”##

For starters, the atomic radius of rubidium cannot be expressed in picometers cubed, ##”pm”^3##, because that is a unit used for volume, not for length.
My guess would be that you’re indeed dealing with the atomic radius of rubidium, which is equal to ##”248 pm”##.
If that’s the case, the first thing to do here would be to convert the desired length, i.e. ##1.00## centimeters, to picometers. To do that, go from centimeters to meters first, then from meters to picometers

##1.00 color(red)(cancel(color(black)(“cm”))) * (1color(red)(cancel(color(black)(“m”))))/(10^2color(red)(cancel(color(black)(“cm”)))) * (10^(12)”pm”)/(1color(red)(cancel(color(black)(“m”)))) = 1.00 * 10^(10)”pm”##

So, you know that the radius of a rubidium atom is equal to ##”248 pm”##. The thing to look out for here is the fact that you need to use the diameter of an atom, which is you know is equal to