Molymod Crystal Structure Molecular Model Kits - Molymod MKO-101-45, A Molymod Molecular Model Set showing the crystaline structure of Graphite.Scales: Open / Ball & stick models: 2.5cm / Angstrom, Closed / semi-space filling models: 1.5cm / AngstromAtom-parts: range from 17 to 23mm in diameter.Bonds: Single bonds are represented by medium links (19mm) and multiple bonds by longer, flexible links (30mm). For compact models, bonds are represented by short links (2mm).Valence: Represented by the number of holes: 1 hole (I), 2 holes (II), 3 holes (III), 4 holes (IV), 5 holes (IV), 6 holes (VI) Molymod MKO-101-45 - Graphite (Three Layer) Crystal Structure Kit - 45 Atoms