Complex sentence: Metallic glasses, for example, are typically well described by the dense random packing of hard spheres, whereas covalent systems, such as silicate glasses, have sparsely packed, strongly bound, tetrahedral network structures.
Split into simpler sentences: Metallic glasses, for example, are typically well described by the dense random packing of hard spheres. Whereas covalent systems, such as silicate glasses, have sparsely packed, strongly bound, tetrahedral network structures.