Nuclear Chemistry

nuclear reactions

reactions that involve a change in the nucleus of the atom (number of protons and/or neutrons changes)

radioactive nuclei

nuclei that lose energy and form new nuclei (undergo radioactive decay)

radioisotopes

radioactive isotopes (ie. isotopes with unstable nuclei that undergo radioactive decay)

Unstable nuclei

When the neutron to proton ratio is too large or too small, it creates an instability and the isotope of that element will decay until a stable forms; few radioisotopes exist in nature and have to be formed. Too big —→ Beta decay. Too small —> Alpha decay.

strong nuclear force

The very strong force that holds the protons and neutrons together in the nucleus (ie. there is A LOT of energy stored in the nucleus of an atom).

energy

Some isotopes with an undesirable number of protons and neutrons will decay to form something more stable; in the process, they release ____.

half-life

the amount of time required for half of the radioisotope to decay; can range from minutes to billions of years.

Alpha

stopped by skin, paper; He nucleus (2p+, neutrons)

Beta

High energy electrons; 1 cm stopped by a book, aluminum.

Gamma

high-energy photon; highly penetrating (thick walls of concrete 3ft, lead).

atomic number; mass number

during nuclear reaction _____ and _____ are conserved.

Dose

The amount of radiation absorbed by the body; unit used is rem (milirem is commonly used: 1 rem = 1,000 mrem)

Sievert

the SI unit for radiation ( 1 Sv = 100 rem)

fusion

combining 2 light nuclei to form a heavier nucleus

• creates even more energy than fission

• stars produce their energy through it (protons combine to form helium—— several steps in this process)

• currently not feasible to perform because energy is not favorable yet

fission

Splitting a heavy nucleus into 2 nuclei with smaller mass numbers.

• occurs when radioactive uranium is bombarded with neutrons.

• process is self-sustaining as the neutrons produced collide with additional nuclei = chain reaction

• the Manhattan Project (atomic bomb) carried out during WWII was based on the principle of nuclear fission