Nuclear Chemistry, Quantum Mechanics

nuclear chemistry

concerned with changes in the nucleus of elements. these changes are the source of radioactivity and nuclear power.

nuclear equation

• sum of the mass number must be the same on both sides

• sum of atomic number must be the same on both sides

nuclide

various species of atoms whose nuclei contain particular numbers of protons and neutrons

nuclear stability

• odd + odd = least stable, more radioactive

• event + even = most stable, least radioactive

• nuclides containing odd numbers of protons and even numbers of neutrons are less stable than nuclides containing even number of protons and odd numbers of neutrons

radioactive decay

emission of energy in the form of ionizing radiation

radioactive decay | alpha decay

nucleus emits an alpha particle (essentially a helium nucleus)

radioactive decay | beta decay

• beta particle (often an electron), but can also be a positron (anti-particle of an electron)

• if an electron is involved, the number of neutrons in the nucleus decreases by one and number of protons increases by one

radioactive decay | gamma decay

• nuclear changes from higher level energy to lower

• nucleus has energy levels

• electron changing level: energy involved is usually a few eV (a visible or ultraviolet photon is emitted)

• nucleus’ energy level differences are much larger (a few hundred keV), its emitted photon is gamma ray

gamma decay | nuclear fission

• neutron slams into a larger atom

• nucleus of an atom splits into two or more smaller nuclei as fission products, and usually some by-product particles

gamma decay | nuclear fusion

• multiple nuclei join together to form a heavier nucleus

gamma decay | half-life, t12

amount of time needed for a reactant concentration to decrease by half compared to its initial concentration

quantum number

set of values that describes the state of an electron including its distance from the nucleus, the orientation and type of orbital where it is likely to be found, and its spin

orbital

quantum states of the individual electrons in the electron cloud around a single atom

principal quantum number (n)

main energy level or principal shell

angular quantum number (l)

shape of the orbital

• n-1

magnetic quantum number (ml)

orientation in space of angular momentum

• e.g., -1, 0, 1

degenerate orbitals

orbitals having the same energies

electron spin quantum number (ms)

• ½, or -½

• values not dependent to any other quantum numbers

• up or down arrow

electronic configuration

summary of where the electrons around a nucleus

order of fill

order in which electrons are placed into the orbitals is based on the order of their energy (Aufbau principle)