Nuclear Chemistry The study of nuclear change Some

Nuclear Chemistry The study of nuclear change. Some elements undergo chemical changes in their nucleus that alters their number of protons or neutrons.

Nucleus • nucleus contains nucleons – p+ and n 0 • atomic mass, a. k. a. mass number – protons + neutrons • atomic number – # protons – identifies the element

Isotopic notation Mass Symbol Atomic number Symbol - Mass

U-242 U-232 U 238 U-234 U 235 U-240 U 234 U-236 U-239 U 226 U 230 U-238 U-229 U 230 U-235 U 228

Transmutation • Sometimes the changes in the nucleus are such that an element is transformed into a different element – change in atomic number An element is considered radioactive because it releases Energy during transmutation

Artificial Transmutation Natural Transmutation • Change in nucleus occurs when occurs spontaneously bombarded by an – The ONLY reactant alpha particle or is the atom neutron undergoing – MUST be a reactant transmutation

FYI. . . • Since 1940, 23 transuranium elements have been formed • All elements with atomic numbers > 93 were synthesized by nuclear reactions • Glenn Seaborg created 10 of these elements – atomic # 94 - 103 • Element #106 was named for him – Seaborgium

Stability of Nuclei • Most nuclei are stable – some elements have unstable isotopes • Radioisotopes / nuclide – Ex. C-12 stable and won’t transmutate C-14 unstable and will transmutate

What causes instability? • As atoms increase in size the ratio of neutrons to protons also increases – the larger the ratio the more unstable the atom – Ex. compare C-14 to U-238 • All nuclei with atomic numbers > 83 are unstable and radioactive

Unstable nuclei will spontaneously decay in order to form a stable nucleus

Types of Radiation • Types of radiation emitted from the nucleus during transmutation – alpha particles 4 He or α 2 – beta particles ß- or – gamma radiation – Positrons β+ or γ

Radiation Penetration

How does Radiation affect cells? • Radiation has the ability to ionize atoms – Ionizing radiation causes damage to tissues by damaging molecules • Most damaging is alpha; least is gamma – Damage to proteins & DNA are most damaging – If radiation exposure is low the body may repair itself – If exposure is high, cells may die or cellular instructions might get “scrambled”

• Radioisotopes are used in diagnosing and treating cancer – I-131 • diagnose thyroid disorders – Co-60 • treat cancer Short half lives decay quickly

Alpha Decay • Alpha particle has to be a product.

Beta Decay • A Beta particle has to be a product

Gamma Radiation • Type of electromagnetic radiation like an x-ray • No charge, no mass, no equations!

• These 3 types of radiation were discovered by Rutherford

Positron Radiation

The End