Radioactive Decay

Spontaneous change from an unstable nuclei to a more stable one Releases particles, electromagnetic waves or both Always transition from unstable to more stable

Characteristics of Nuclear Particles and Rays

Alpha Decay Nucleus with large N/Z ratio Emits an alpha particle Basically a helium atom- 2 protons, 2 neutrons Atomic number decreases by 2 Mass number decreases by 4

Beta Decay Occurs usually with large N/Z number Neutron breaks apart into a proton and basically an electron The electron is shot out of the nucleus as a beta particle The proton stays in the nucleus Atomic number increases by 1 Mass number stays the same

Electron Capture If nucleus has too many protons It can absorb an electron from the electron cloud The e- combines with the proton to make a neutron and gamma rays are given off Atomic number decreases by 1 Mass number stays the same.

Positron Emission If too many protons Proton breaks down and makes a neutron and a positron Positron leaves the nucleus and usually hits an e-, its antiparticle When they hit they undergo annihilation of matter emitting gamma rays Atomic number decreases by 1 Mass number stays the same

Gamma Decay High energy electromagnetic waves emitted from a nucleus as it changes from an excited state to a ground state Energy is release when nucleons go to a lower nuclear energy shell Usually follows other types of decay that leave the nucleus in an excited state Atomic number stays same Mass number stays same

Decay Series Sometimes unstable nuclei go through a series of nuclear decays called a decay series Rules for radioactive decay All nuclear equations must be balanced

Transmutations Change in the identity of a nucleus the number of protons changes Bombardment of nuclei with charged and uncharged particles Neutrons penetrate easily Charged particles need energy to do so and are accelerated to make it happen Artificial radioactive nuclei are not found in nature Used to make transuranium elements Elements with more than 92 protons All are radioactive

Type Atomic Number Mass Number Particle(s) Involved Alpha 2 4 4 2 𝐻𝑒 Beta 1 0 −1 𝑒 Electron Capture 0 −1 𝑒, ϒ Positron Emission 0 +1 𝑒, ϒ Gamma ϒ

Beta decay- strontium-90 Alpha decay- uranium-233 Positron decay- nitrogen-13 Electron capture- cobalt-57