Atom Geometry Bond Pegs
The "Unit" large molecular model set atoms can be configured with any standard VSEPR geometry by means of 3 different "bond pegs" as shown in the image.
The leftmost bond peg is the 4/8 which is used to construct the most common geometry, tetrahedral (sp3) or 8 coordinate (metals).
The central, radial peg is typically used to build univalent atoms when 1 is used; 180o (linear) or angled shapes when 2 are used & trigonal when 3 are used & placed 60 degrees apart. They can also be combined with other pegs for any non-standard VSEPR geometry.
The polar peg shown to the right can be used one or two at a time for univalent and 180o linear shapes respectively or with the radial peg to form trigonal bipyramidal or octahedral geometries.