  With the advent of atomic-resolution transmission electron microscopy
(AR-TEM) achieving sub-{\AA}ngstrom image resolution and submillisecond time
resolution, an era of visual molecular science where chemists can visually
study the time evolution of molecular motions and reactions at atomistic
precision has arrived. However, the appearance of experimental TEM images often
differs greatly from that of conventional molecular models, and the images are
difficult to decipher unless we know in advance the structure of the specimen
molecules. The difference arises from the fundamental design of the molecular
models that represent atomic connectivity and/or the electronic properties of
molecules rather than the nuclear charge of atoms and electrostatic potentials
that are felt by the e-beam in TEM imaging. We found a good correlation between
the atomic number (Z) and the atomic size seen in TEM images when we consider
shot noise in digital images. We propose here Z-correlated (ZC) atomic radii
for modeling AR-TEM images of single molecules and ultrathin crystals, with
which we can develop a good estimate of the molecular structure from the TEM
image much more easily than with conventional molecular models. Two parameter
sets were developed for TEM images recorded under high-noise (ZCHN) and
low-noise (ZCLN) conditions. The new molecular models will stimulate the
imaginations of chemists planning to use AR-TEM for their research.
