AP BIOLOGY

Detailed explanation-1: -A compound with trigonal planar molecular geometry has a central atom bonded to three other atoms or groups. As it has no lone pairs of electron pairs, the three groups to which it is bonded are arranged like a triangle around the central atom, with the bond angles measuring 120 degrees.

Detailed explanation-2: -A trigonal planar molecular geometry model has one atom in the centre and three atoms at the corners of an equilateral triangle, known as peripheral atoms, all in the same plane. All three ligands in an ideal trigonal planar species are identical, and all bond angles are 120°.

Detailed explanation-3: -If there is one lone pair of electrons and three bond pairs the resulting molecular geometry is trigonal pyramidal (e.g. NH3).

Detailed explanation-4: -The central and surrounding atoms in a trigonal planar molecule lie on one plane (hence the term planar). This gives it more of a two-dimensional shape than three-dimensional. The bonds are spread equally around the plane, forming 120 degree bond angles.

Detailed explanation-5: -The trigonal pyramidal geometry exists when there are 3 bonds and 1 lone pair. This is seen in ammonia (right). The bond angle for trigonal pyramidal geometries is less than 109.5∘ due to the additional repulsion from the lone pair.