A model of dissociative chemisorption on a surface with a square latti
ce was studied using the Monte Carlo method. The model is based on two
chemisorption pathways: ''direct'' - nucleation of adsorption islands
, and ''indirect'' - their growth. The development of the surface dist
ribution picture of chemisorbed particles was found to depend signific
antly on the contribution of these two pathways (S-indir/S-dir).