As the size of a particle decreases to the nanoscale, the surface area to volume ratio increases dramatically. This means that a greater fraction of the atoms are located on the surface rather than in the bulk of the material. This can lead to enhanced chemical reactivity, as surface atoms often have unsatisfied or dangling bonds that are more reactive compared to those in the bulk. For instance, gold nanoparticles exhibit higher catalytic activity compared to bulk gold due to their increased surface reactivity.
