Nuclear Chemistry Nuclear Reactions

Reactions Chemical Reactions- atoms want stable electron configuration Nuclear Reaction- unstable isotopes (radioisotope) want to be stable –Produces large amounts of energy

Questions What part of an atom is involved in chemical Reactions? –Valence electrons What is the difference between chemical reactions and nuclear reactions? –Chemical reactions electrons configuration changes, nuclear the nucleus of an atom changes

Radioactivity In 1896 Becquerel was studying uranium salts ability to fog photographic film plates Marie Curie (assistant) found that uranium emitted rays that caused fog Process of giving off rays called radioactivity Penetrating rays emitted by radioactive source called radiation

Radioactivity Nuclear reactions are not affected by changes in temperature, pressure, or catalysts Can’t be turned off, slowed downed, or sped up –Bad when a melt down occurs

Radioactivity Radioactivity atom- radioisotope changes as it emits radiation Radioisotopes have unstable nucleus Stability depends on ratio of neutrons to protons

Radioactivity Too many or too few neutrons leads to an unstable nucleus An unstable nucleus loses energy- radioactive decay Eventually turn in to a stable isotope of another element

Radiation What types of radiation are there? –Alpha, beta, and gamma All are somewhat harmful, but gamma is dangerous because it can penetrate body tissue

Chain Reaction

Mass of Particles Proton and neutrons are 1 amu Electrons are 1/1840 of proton As radioisotopes change they give off energy which has a mass, very slight, so there mass changes E=MC 2 energy equals mass x speed of light squared

Alpha Radiation Alpha particles are helium nuclei- two neutrons and two protons which have a double positive charge. Uranium radioisotope changes into thorium radioisotope What is the atomic number and mass number of uranium and thorium?

Alpha Radiation When an atom loses an alpha particle its atomic number is lowered by two and its mass number is lowered by four. Alpha particles don’t travel far and don’t penetrate. Stopped by a sheet of paper.

Beta Radiation Beta particles are fast moving electrons formed by the decomposition of a neutron Neutron turns into a proton and an electron is released The electron released is a beta particle

Beta Radiation When Carbon 14 an isotope emits a beta particle it turns in to Nitrogen 14 What is the atomic number and mass number of carbon 14 and nitrogen 14?

Beta Particles Beta particles have much less mass than alpha particles therefore can penetrate deeper. Stopped by Al foil or thin piece of wood

Gamma radiation High energy electromagnetic radiation given off by a radioisotope Visible light is lower energy electromagnetic radiation X-rays are like gamma rays

Gamma radiation Gamma particles have no mass and no electrical charge. X- rays made when excited electrons in certain metals lose energy X- rays and gamma rays are very penetrating only stopped by thick concrete