12 C 6 Nuclear Symbols Mass number Atomic number Carbon-12
Nuclear Reactions • Unstable nuclei undergo spontaneous changes that change their number of protons and neutrons. • A nuclear reaction is a reaction that affects the nucleus of an atom.
Section 2: Radioactive Decay • Radioactive Decay: is the spontaneous disintegration of a nucleus into a slightly lighter nucleus. This leads to more stable nucleons. • 3 types of radioactive decay • Alpha Emission • Beta Emission • Gamma Emission
Alpha Emission • An alpha particle (α) is a helium nucleus. • Lowest penetrating power. • Alpha emission is restricted almost entirely to very heavy nuclei. 21084Po 20682Pb + 42He
Beta Emission • Abeta particle (β or e) is an electron emitted from the nucleus during some kinds of radioactive decay. • To decrease the number of neutrons, a neutron can be converted into a proton and an electron. 146C 147N + 0-1e
Gamma Emission Gamma rays () are high-energy electromagnetic waves emitted from a nucleus as it changes from an excited state to a ground energy state. -Gamma rays don’t actually change the nucleus of an atom.
Write the Nuclear Reaction for: The a decay of Americum-245
Half-life • Half-life,t1/2, is the time required for half the atoms of a radioactive nuclide to decay. • Each radioactive nuclide has its own half-life. • More-stable nuclides decay slowly and have longer half-lives.
Potassium 40 half-life • If 28 grams of an isotope has a half life of 3 years, how much would remain after 3 years? • How much would remain after 6 years?