Nuclear Applications

1H is stable with 0 neutrons iso Natural Abundance half-life Decay Mode Decay Energy Decay Product 1H 99.9885% 1H is stable with 0 neutrons 2H 0.0115% 2H is stable with 1 neutron 3H trace 12.32y β− 0.01861 3He

Source of Radioisotopes - radioactive isotope of an element 1. Created from stable isotopes neutron bombardment—disturbs the 1:1 OR 1.5:1 N:P ratio and causes instability in the nucleus Naturally radioactive elements All elements heavier than bismuth are naturally radioactive due to their instability. They are artificially created. All elements heavier than uranium are formed by bombarding a heavy atom with neutrons or alpha particles.

Properties of Radioactive Elements Can cause some other substances to fluoresce, or glow in the dark. Prolonged exposure can cause damage to cells. This is the hand of a doctor that performed x-rays for 15 years without protecting his body.

Uses of Radioactivity Medical Radiation therapy for cancer – chemotherapy In low doses, ionizing radiation induces cancer. In high doses it destroys cells. Radioactive tracers for medical diagnosis and research- nuclear medicine imaging radioactive tags and monitor the location of the radioactivity with time

Uses of Radioactivity Food Irradiation Smoke detectors Nuclear power Food can be irradiated with g rays from 60Co or 137Cs. Irradiated milk has a shelf life of 3 mo. without refrigeration. USDA has approved irradiation of meats and eggs. Smoke detectors Nuclear power

Uses of Radioactivity Radioactive Dating Fossils are dated by knowing the ratio of parent element (radioactive) to daughter element (what is left after radioactive decay.) Two things must be known: length of half-life and ratio of parent:daughter.

Half Life of Radioisotopes Half life is the amount of time it takes for one half of a radioactive element to change from the parent (radioactive) to daughter (product) element Example: The half life of Ra-226 is 1600 years. How much of a 10.0 gram sample will remain after 3 half lives? 1 half-life 10.0 g  5.0 g 2 half-lives 5.0 g  2.5 g 3 half-lives 2.5 g  1.25 g 4800 years!!!

Graph of Half Life

Radioactive Dating The Carbon-14 isotope is used for wood, bones, tissue, anything that used to be alive. All living things contain carbon, and part of the carbon is C-14 (Most is C-12). After something dies, it stops exchanging carbon with the atmosphere and the C-14 begins to decay. Because we know the half-life of C-14 to be 5730 years, we can measure the amount of C-14 left and calculate how long the organism has been dead.

Skittles Lab!