Isotopes & Radioactivity

Isotopes of Magnesium Atomic symbol Mg Mg Mg Number of protons Number of electrons Mass number Number of neutrons Isotope Notation Mg-24 Mg-25 Mg-26 Timberlake, Chemistry 7 th Edition, page 64 12p + 12n 0 12p + 13n 0 12p + 14n 0 12e -

Isotopes of Hydrogen 1 p + 1 e - 1 p + 1 n 1 e - 1 p+ 2 n 1 e - ProtiumDeuteriumTritium (ordinary hydrogen) (heavy hydrogen)(radioactive hydrogen) Ralph A. Burns, Fundamentals of Chemistry 1999, page 100 H-2H-3H-1

Isotopes of Hydrogen ProtiumProtium (H-1) 1 proton, 0 neutrons, 1 electron most abundant isotope DeuteriumDeuterium (H-2) 1 proton, 1 neutron, 1 electron used in “heavy water” TritiumTritium (H-3) 1 proton, 2 neutrons, 1 electron radioactive 1 p + 1 e - 1 p + 1 n 1 e - 1 p+ 2 n 1 e -

Isotopes of Three Common Elements ElementSymbol Fractional Abundance Average Atomic Mass Carbon Chlorine Silicon Si % 4.70% 3.09% % C 98.89% 12 (exactly)12 C Mass (amu) 75.53% 24.47% Cl Cl Mass Number LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World, 1996, page 110

Radioactivity (1896) 1. rays or particles produced by unstable nuclei a. Alpha Rays – helium nucleus b. Beta Part. – high speed electron c. Gamma ray – high energy x-ray 2. Discovered by Becquerel – exposed photographic film 3. Further work by Curies Antoine-Henri Becquerel ( )

Radioactivity Marie CurieOne of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie ( ). She discovered radioactivity, the spontaneous disintegration of some elements into smaller pieces.

Radioisotopes Radioactive isotopes Many uses –Medical diagnostics –Optimal composition of fertilizers –Abrasion studies in engines and tires Radioisotope is injected into the bloodstream to observe circulation.

Half-Life of Isotopes Isotope Half-Life Radiation emitted Half-Lives and Radiation of Some Naturally Occurring Radioisotopes Carbon x 10 3 years  Potassium x 10 9 years  Thorium days  Radon days  Radium x 10 3 years  Thorium x 10 4 years  Uranium x 10 8 years  Uranium x 10 9 years 

Atomic Structure Review ATOMSATOMS –Differ by number of protons IONSIONS –Differ by number of electrons ISOTOPESISOTOPES –Differ by number of neutrons