: On an atomic level, radioactive decay is random. You cannot predict when a single atom will decay, but you can precisely predict the behavior of a large group of atoms. 2. The Core Formulas
Half-life ( t1/2t sub 1 / 2 end-sub ) is the time required for a quantity to reduce to of its initial value. While most commonly associated with radioactive decay , the concept also applies to pharmacology (how long a drug stays in your system) and even the "decay" of information or marketing effectiveness. 1. Key Principles half lfe
: The substance doesn't disappear linearly. After one half-life, 50% remains; after two, 25% remains; after three, 12.5% remains, and so on. : On an atomic level, radioactive decay is random