Structures of Solids

metallic, ionic, covalent network, molecular

held together by a “sea” of shared electrons(nuclei like islands), this allows metals to conduct electricity and be strong and NOT brittle Ex: Cu, Fe

Held together by strong attraction between cations and anions. They generally do NOT conduct electricity Ex: NaCl, MgO

Held together by covalent bonds. Typically a bunch of non-metals. This bonding type makes materials very hard (like diamonds). Semiconductors Ex: diamond, graphite

Held together by the intermolecular forces (hydrogen-bonding, dipole-dipole, dispersion). This is the weakest solid. Soft, low melting points. Ex: HBr, H2O

a small repeating unit stacked over and over, 3-dimensionally, in all directions to make a solid

1) simple cubic 2) body-centered cubic 3) face-centered cubic

1 atom per unit cell. Atoms at corners of cube (so 8 atoms each, bot only 1/8 of each atom is inside the box. So only ONE full atom for unit)

2 atoms per unit cell. #1 fully inside the box and eight straddling each corner making #2 (1/8*8=1)

4 atoms per unit cell. atoms at corners and on flat surface sides. half of each atom on the sides is inside the box. (corners= 1/88=1, sides =1/26=3)