What is the range of neutron to proton ratios for stable isotopes?

The range of neutron to proton ratiOS for stable isotopes typically falls between about 1:1 to 1.6:1. For lighter elements, stable isotopes generally have a neutron-to-proton ratio close to 1. As the atomic number increases, the ratio tends to rise, reflecting the need for more neutrons to counteract the increasing electrostatic repulsion between protons in the nucleus. Isotopes outside this range are often unstable and prone to radioactive decay.