Question

The radius of an atom of krypton (Kr) is about 1.9 angstroms. (a)Express this distance in nanometers (nm) and in picometers (pm). (b)How many krypton atoms would have to be lined up to span 1.0mm? (c)If the atom is assumed to be a sphere, what is the volume in cm^3 of a single Kr atom?

Answer 1

a) 1.9 Ao = 1.9 x 10^-8 cm

             = 1.9 x 10^-10 m

              = 1.9 x 10^-1 nm

             = 0.19 nm

b)

1.9 x 10^-10 m = 190 x 10^-12 m

                        = 190 pm

c)

length = 1.0 mm = 1.0 x 10^-3 m

number of atoms = 1.0 x 10^-3 / 1.9 x 10^-10

                            = 5.26 x 10^6 atoms

d)

sphere volume = 4/3 pi r^3

                          = 4 x 3.14 x (1.9 x 10^-8)^3 / 3

                         = 2.87 x 10^-23 cm^3