Nuclear Chemistry

Why Study Nuclear Chemistry Medical Applications Medical Applications X-Rays X-Rays Radiation Treatments Radiation Treatments Scans (CAT, PET etc). Scans (CAT, PET etc). Production of electrical power Production of electrical power Warfare: Discovery of Atomic and Hydrogen Bombs Warfare: Discovery of Atomic and Hydrogen Bombs

Characteristics of Chemical and Nuclear Reactions Chemical Reactions Nuclear Reactions 1. Occur when bonds are broken and formed 1. Occur when nuclei emit particles and/or rays 2. Atoms remain unchanged, though they may be rearranged 2. Atoms are often converted into atoms of another element 3. Involve only valence electrons 3. May involve protons, neutrons, or electrons 4. Associated with small energy changes 4. Associated with large energy changes.

Radioactive Decay Isotope- Atoms of the same element that have the same number of protons and different numbers of neutrons Isotope- Atoms of the same element that have the same number of protons and different numbers of neutrons Radioisotope- An isotope that has an unstable nucleus and undergoes radioactive decay. Radioisotope- An isotope that has an unstable nucleus and undergoes radioactive decay. Number of protons may change! Radioactive decay - unstable atoms lose energy by emitting one of several types of radiation Radioactive decay - unstable atoms lose energy by emitting one of several types of radiation Three most common types- alpha, beta, and gamma Three most common types- alpha, beta, and gamma All nuclei with atomic number greater than 83 are radioactive! All nuclei with atomic number greater than 83 are radioactive!

Properties of Radiation PropertyAlphaBetaGamma Symbol Description Helium Nuclei ElectronsPhotons Charge2+1-0 Relative Penetrating Power Blocked by Paper Blocked by metal foil Blocked by lead or concrete.

Power of particles

Alpha Radiation Mass Number Atomic Number

Alpha Radiation

Beta Radiation Mass Number Atomic Number

Beta Radiation

Gamma Radiation A gamma ray does not consist of particles but accompanies alpha and beta radiation and is much more penetrating than either of them.

Gamma Radiation

Practice! Uranium-233 undergoes alpha decay Uranium-233 undergoes alpha decay Copper-66 undergoes beta decay Copper-66 undergoes beta decay

Let’s review the bookwork! Page 653 # 1-4 Page 653 # 1-4

Lab! M&M Half Life Lab M&M Half Life Lab

Alpha Particles Consists of Helium Nuclei that has been emitted from a radioactive source Consists of Helium Nuclei that has been emitted from a radioactive source Contain two protons and two neutrons and have a charge of +2 Contain two protons and two neutrons and have a charge of +2 Particles do not travel far and are not very penetrating Particles do not travel far and are not very penetrating Easily stopped by a sheet of paper or by the surface of your skin Easily stopped by a sheet of paper or by the surface of your skin Alpha particles are VERY dangerous when ingested. Alpha particles are VERY dangerous when ingested.

Beta Radiation Consists of fast moving electrons formed by the decomposition of a neutron in an atom Consists of fast moving electrons formed by the decomposition of a neutron in an atom Neutron breaks into a proton (which stays in the nucleus) and an electron that is released. Neutron breaks into a proton (which stays in the nucleus) and an electron that is released. Beta particles are more penetrating and are stopped by aluminum foil or thin pieces of wood Beta particles are more penetrating and are stopped by aluminum foil or thin pieces of wood

Gamma Rays High energy electromagnetic Radiation High energy electromagnetic Radiation Often emitted with alpha and beta radiation Often emitted with alpha and beta radiation Has no mass and no charge Has no mass and no charge Does not effect the atomic number or atomic mass of an element Does not effect the atomic number or atomic mass of an element Pass through paper, wood and the human body Pass through paper, wood and the human body Can be stopped by several meters of concrete or several cm of lead Can be stopped by several meters of concrete or several cm of lead

Nuclear Ratios- Band of Stability

Nuclear Stability There are 1500 different nuclei, only 264 of those are stable and do not decay or change over time. There are 1500 different nuclei, only 264 of those are stable and do not decay or change over time. Stability depends on the neutron to protons ratio (n:p) Stability depends on the neutron to protons ratio (n:p) Below atomic number 20 Below atomic number 20 Ratio is 1:1 Ratio is 1:1 Above atomic number 20 Above atomic number 20 Ratio is greater than 1:1 Ratio is greater than 1:1 More neutrons than protons More neutrons than protons Unstable nuclei undergo spontaneous radioactive decay Unstable nuclei undergo spontaneous radioactive decay The type of decay depends on the neutron to proton ratio of the nucleus The type of decay depends on the neutron to proton ratio of the nucleus

Marie and Pierre Curie Took phosphorescent materials and isolated the components that emitted rays Took phosphorescent materials and isolated the components that emitted rays She concluded that the source came directly from the atoms themselves She concluded that the source came directly from the atoms themselves Marie named the process by which materials give off such rays RADIOACTIVITY Marie named the process by which materials give off such rays RADIOACTIVITY Radiation= penetrating rays and particles emitted by a radioactive source Radiation= penetrating rays and particles emitted by a radioactive source Marie Curie won the Nobel Prize in Physics in 1903, and in Chemistry in Marie Curie won the Nobel Prize in Physics in 1903, and in Chemistry in 1911.