If you construct a diagram of a fcc crystal, the atoms touch along the diagonal but they don't touch along the edges. So one edge is 508, the other edge is 508 and the diagonal is sin 45o = 508/x
x = length of the diagonal. It will be 4r in length.
So radius A + 2*radius B + radius A = x
You know radius A, solve for radius B. Post your work if you get stuck. I urge you to look a diagram, either in your text/notes or on the web to see how this fits.
The edge length of face centered unit cubic cell is 508pm.if the radius of the cation is 110 pm,the radius of anion is
1 answer
1 answer