Kev txhais ntawm radioactivity
Radioactivity txhais tau tias cov khoom ua ntu zus los ntawm cov hluav taws xob tsis ruaj khov (xws li alpha rays, beta rays, gamma rays, thiab lwm yam) thiab lwj los ua cov hauv paus ruaj khov thiab nres hluav taws xob (khoom lwj). Qhov tshwm sim no yog hu ua radioactivity. Lub zog tso tawm thaum lub cev lwj yog hu ua lwj lub zog. Cov ntsiab lus nrog cov atomic number ntawm 83 (bismuth) lossis siab dua yog hluav taws xob, tab sis qee cov khoom siv nrog cov atomic tsawg dua 83 (xws li technetium) kuj yog radioactive.