Question

An atom of rhodium (Rh) has a diameter of about 2.7×10−8cm.

What is the radius of a rhodium atom in angstroms (Å)?

r =

1.4

Å

What is the radius of a rhodium atom in meters (m)?

r =

1.4×10−10

### How many Rh atoms would have to be placed side by side to span a distance of 9.5 μm ?
Express your answer using two significant figures.

### If the atom is assumed to be a sphere, what is the volume in m3 of a single Rh atom?
Express your answer using two significant figures.
(Hint: Do not use the rounded answer from Part A - use a radius that has not been rounded to avoid introducing rounding error into your calculation.)

Answer 1

Rh atom has diameter = 2.7 x 10^-8 cm

Rh radius = 2.7 x 10^-8/2 = 1.35 x 10^-8 cm

Rh radius in Angstrom = 1.35 Angstrom

Rh radius in meter = 1.35 x 10^-8 cm/100 = 1.35 x 10^-10 m

to cover distance of span = 9.5 um = 95,000 Angstrom

Number of Rh atoms needed = 95,000/2.7 = 35185.2 atoms

Volume of single Rh atom = (4/3).pi.r^3

                                          = (4/3) x 3.14 x (1.35 x 10^-10)^3

                                          = 1.03 x 10^-29 m^3