Polymorf - Knowhwere- Elements

The geometry and symmetry of the elements

By definition elements are composed of only one type of atom species. Therefore

their atomic structures lend themselves readily to being modeled as packings of

equal radius spheres. The majority of elements exhibit either FCC, HCP, or BCC

packing of their atoms.

Lanthanides

Actinides

Table 2 - Periodic table of the elements showing atomic packing arrangement

(all elements, including gases, considered to be in their solid state)

The BCC structure is favored by elements with low numbers of valence electrons.

Elements with larger numbers of valence electrons favor the closer packed FCC and

HCP structures.

Face centered cubic (FCC) structure elements

Ac, Ag, Al, Ar, Au, Ce, Cu, In, Ir, Kr, Ne, Ni, Pb, Pb, Pd, Pt, Rh, Th, Xe

Crystal lattice


		Figure 45 - FCC elements crystal lattice

		click image to enlarge
.

The above image shows the ABC staggered arrangement of the successive layers

of atoms characteristic of the FCC lattice. The view is taken looking down on the

(111) plane which is comprised of atoms in the triangulated closest packed array. In

the process of building this model of the lattice the structural stability afforded by the

omni-triangulation of 3D space can be appreciated first hand.

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Page 31 - Structure matters - FCC elements