hexagonal close packing

Hexagonal close packing (HCP) is a highly efficient way atoms arrange themselves in a solid. Imagine stacking layers of spheres (atoms) so each sphere fits into the gaps of the layer below, forming a pattern with hexagon-shaped repeating units. Each layer is arranged in a way that maximizes space and minimizes empty gaps, leading to a dense, tightly packed structure. In HCP, layers alternate in a specific pattern, resulting in a crystalline structure that is strong and stable. This arrangement is common in metals like titanium and magnesium, providing their characteristic strength and density.