CHEM101 Lecture Notes - Lecture 33: Cubic Crystal System, Cubical Atom, Atomic Radius

• School: University of Alberta
• Department: Chemistry
• Course: CHEM101
• Professor: Rylan Lundgren

Document Summary

At room temperature, iron crystallizes in the body centre cubic structure. The edge of the cubic cell (unit cell) is found to be 287 pm. In body centred cubic atoms at the corners are not in contact with each other. Corner to corner distance is = 2r: al crystallizes in the face centered cubic structure. The paricles at the corner do not touch, they are in contact with the paricles at the face. Corner to face center distance is 2r. # of atoms in the cell: 4 al atoms per unit cell. Overview: unit cells, densiies, radii: determining atomic radii from unit cell parameters (l) and vice versa. For body centred cubic (where all atoms are the same) r = [sqrt3 / 4] l or l = [4 / sqrt3] r. For face centered cubic r = sqrt2 / 4 l or l = [4 / sqrt2] r.