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Name: Susan
Status: Teacher
Grade: Other
Location: OH
Country: USA
Date: July 2006

Approximately how many carbon atoms (one atom thick) would "fit" on the period at the end of a standard text sentence?


Let us say that the carbon atoms are solid spheres with the radius equivalent to its Van der Waal's radius (approximately 0.17nanometers). Let us say that a 12 font size period has a radius of about 0.25millimeters . . . I think you can do the math.

Greg (Roberto Gregorius)

Hi Susan,

I will start with the assumption you are referring to graphite, since graphite and diamond have different crystal structures, hence will yield different answers. I measured the period size in my local newspaper, and it is almost dead on 0.5mm diameter. Graphite is composed of layers or sheets of carbon atoms 1 atom thick, arranged in adjoining hexagon "cells", much like honeycomb appears when looking at it. It is generally agreed that the average distance between any one carbon atom and its neighbors in a graphite crystal is 1.42 Angstroms (or 1.42 x 10^-7 mm).

Therefore one can see that with a bit of arithmetic and a little simple trigonometry, it works out that approximately 7.5 x 10^12 (that is, 7.5 trillion) carbon atoms arranged as a single graphite crystal, one layer thick, will fit in a 0.5mm diameter circle (the size of a printed period).

Bob Wilson.

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