7.1 Atomic Theory and Radioactive Decay

Early Pioneers in Radioactivity Rutherford: Discoverer Alpha and Beta rays 1897 Roentgen: Discoverer of X-rays 1895 The Curies : (Marie, Pierre) Led to the developing the field of nuclear chemistry Becquerel: Discoverer of Radioactivity 1896

Periodic Table Form vs. Radioactyive Form "X" represents the scientific abbreviation given for the symbol "A” represents the mass number "Z“ represents the atomic number Also be written as Carbon-12 12 represents atomic mass 6 C Carbon 12.0 Periodic Table Form

Isotopes and Mass Number Isotopes have the same number of protons, But differ in the number of neutrons An element may have only certain isotopes that are radioactive. These are called radioisotopes

Rutherford identified 3 types of radiation 1) Positive alpha radiation α 2) Negative beta radiation β 3) Neutral gamma radiation γ

Alpha Radiation  alpha particles Positively charged, 2+

Beta Radiation (Beta Decay) Beta partcile Negatively charged, 1- neutron  a proton + an electron.

Uranium is releasing an Alpha particle, and Gamma Radiation Gamma decay results from energy being released from a high-energy nucleus., it is shown by: Gamma radiation has no charge and no mass. Uranium is releasing an Alpha particle, and Gamma Radiation