Nuclear Chemistry. Radioactivity : Definition: occurs when the nucleus of an unstable atom emits...

Nuclear Chemistry

Radioactivity:

Definition: occurs when the nucleus of an unstable atom emits ionizing radiation

Radiation- the movement of energy by particles or wavesElectromagnetic radiation

Non-ionizing Radiation- low energy; usually not harmful

Ionizing Radiation- carry enough energy to “ionize” atoms

Elements after atomic number 83 are radioactive

Isotope –

Radioisotope-

Nuclear Reactions Involve a change in the atom’s

nucleus (protons and neutrons)

Types:FissionFusion

Types of RadiationAlpha α (Alpha Decay)

Alpha particle = 2p+ and 2n0

U Th + He + 2 + ϒ

Alpha particle is a He nucleusϒ accounts for energy lost during reactionIn the reaction, we must conserve p+ and n0

Don’t penetrate too far, but can cause skin problemsSources have a long half-life (around for a long time)Discovered by Rutherford and his students (Geiger)

Types of RadiationBeta ϐ (Beta Decay)

Beta particle: fast moving electron (-1 charge) ϐ or eFormed when a neutron is split into a proton and a ϐ

particle (electron) n p + ϐ + ϒ

There is no change in the mass #, only in atomic #Atomic # changes because the e- emitted during ϐ rxn (ϐ

decay) has been removed from a neutron (charge of 0) leaving behind a proton

Rb Sr + e-

Damaging to skin because they can travel through a few inches of tissue

Types of RadiationGamma Rays

Gamma Rays: high energy radiation (electromagnetic) that is massless

No electrical chargeOften accompany α and ϐ reactionsHarmful- can deeply penetrate skin

http://www.bcm.edu/bodycomplab/Radprimer/radpenetration.htm

Electromagnetic Spectrum

Practice Equations:

Radiation ExposureAccumulated Doses

Measured in units called rem: measures doses of radiation while accounting for energy of radiation, type of living tissue absorbing radiation and time of exposure.

Background radiation- Where does this it come from?

Radiation ExposureHow do we detect radiation?

Geiger CounterTube filled with gas that absorbs radiation and

becomes ionized charge current measure the amount of radiation