# Homework Help: Hexagonal Packing Factor - Functional Molecules

1. Sep 8, 2011

### VooDoo

1. The problem statement, all variables and given/known data

the sulphur atoms in the self-assembled monolayers are ~ 4.99Å apart, and that they form a hexagonal close-pack structure, estimate the number of functional molecules/cm2 of the substrate

2. Relevant equations
1 angstrom = 1.0 × 10$^{-10}$ metres

Area of hexagon = 2.598t$^{2}$ where t=length of hexagon side

APF of a hexagonal structure = 0.74

3. The attempt at a solution

I have tried searching google, but the only solution I can come up with is:

Working out the area of the hexagon, by assuming that the 4.99Å is the length of the hexagon side. Then I believe a HCP structure has 7 atoms, therefore I divide the area calculated by 7 to get molecules/Å$^{2}$ which I convert to molecules/cm$^{2}$

No idea if what I am doing is correct!
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution