Solids are classified into various categories (crystal lattice) according to the nature of the repetitive units (motifs) that make up the crystal and the bonds between them. However, this classification cannot be considered a sharp delineation of individual types. Instead, within most crystals there are transitions between the different types, just as there are transitions between bond types as well.
- Metallic crystals
- Metallic crystals consist of a regular arrangement of metal cations with electrons that hold the crystal together (Abb. 2) .
- Ionic crystals
- Ionic crystals consist of and . The stem from ionic attraction (Abb. 3) .
- Atomic crystals
- Atomic crystals ( ) consist of atoms linked by (Abb. 4) .
- Molecular crystals
- Molecular crystals consist of separate molecules held together by . Crystals of the noble gases may be considered a special case as their atoms will form crystal lattices held together by induced dipoles at low temperatures (Abb. 5) .