Science / Biology / Atom: The smallest indivisible particle of matter that can have an independent existence.

Atomic Mass Unit

Science / Chemistry / Atomic Mass Unit: A unit of mass equal to 1/12 the mass of a carbon-12 nucleus, which is 1.660 538 73 × 10-27 kg ± 0.000 000 13 × 10-27 kg [1998 CODATA values]. Abbreviated as amu or u. Sometimes called the dalton, MORE

Polyatomic Molecule

Science / Chemistry / Polyatomic Molecule: A polyatomic molecule is an uncharged particle that contains more than two atoms. MORE

Atomic Unit

Science / Chemistry / Atomic Unit: Compare with Bohr radius and hartree. A system of non-SI units used in quantum chemistry to simplify calculations and mathematical expressions. The definitions of atomic units include physical constan MORE

Enthalpy Of Atomization

Science / Chemistry / Enthalpy Of Atomization: The change in enthalpy that occurs when one mole of a compound is converted into gaseous atoms. All bonds in the compound are broken in atomization and none are formed, so enthalpies of atomization ar MORE

Bohr Atom

Science / Chemistry / Bohr Atom: A model of the atom that explains emission and absorption of radiation as transitions between stationary electronic states in which the electron orbits the nucleus at a definite distance. The Bohr mod MORE

Polyatomic Ion

Science / Chemistry / Polyatomic Ion: A polyatomic ion is a charged particle that contains more than two covalently bound atoms. See Polyatomic Ions for more. MORE