How does the ratio of neutrons to protons for stable nuclei change as atomic number increases from 1 to 82?

As atomic number increases from 1 to 82, the ratio of neutrons to protons in stable nuclei generally increases. For lighter elements, stable nuclei tend to have a neutron-to-proton ratio close to 1:1. However, as the atomic number increases, more neutrons are needed to offset the repulsive forces between the increasingly numerous protons, resulting in a ratio that can exceed 1.5:1 for heavier elements. This trend helps maintain nuclear stability amidst the growing electrostatic repulsion among protons.