Infographics / Nuclear Medicine

Nuclear stability line (N vs Z)

Neutron number N is plotted vertically against proton number Z horizontally. A dashed reference line marks N equal to Z. The teal valley of stability follows N approximately equal to Z for light nuclei, such as carbon-12, and curves so that N is greater than Z for heavy nuclei, such as lead-208. Nuclei above the curve are neutron-rich and decay by beta-minus emission; nuclei below the curve are proton-rich and decay by beta-plus emission or electron capture; the very heavy nuclei at the top of the curve decay by alpha emission. Each arrow points back toward the valley of stability.

Chart of the nuclides: line of stability and decay regions on an N versus Z plot Neutron number N is plotted vertically against proton number Z horizontally. A dashed reference line marks N equal to Z. The teal valley of stability follows N approximately equal to Z for light nuclei, such as carbon-12, and curves so that N is greater than Z for heavy nuclei, such as lead-208. Nuclei above the curve are neutron-rich and decay by beta-minus emission; nuclei below the curve are proton-rich and decay by beta-plus emission or electron capture; the very heavy nuclei at the top of the curve decay by alpha emission. Each arrow points back toward the valley of stability. Chart of the nuclides: stability and decay modes 0 40 80 120 20 40 60 80 proton number Z neutron number N N = Z carbon-12 (N/Z = 1) lead-208 (N/Z ≈ 1.54) neutron-rich too many neutrons β− decay (n → p) proton-rich too many protons β+ decay / electron capture very heavy nuclei α decay (N and Z both fall) valley (line) of stability N = Z reference (equal numbers)
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