Relativistic quantum chemistry is a branch of quantum chemistry that applies relativistic mechanics, and, in particular the Dirac equation or approximation to it (e.g., at the lowest level, the Pauli equation), to electron dynamics and chemical bonding, especially the behavior of the heavier elements of the periodic table. Quantum chemistry is a branch of theoretical chemistry, which applies quantum mechanics to problems in chemistry. ... Albert Einsteins theory of relativity is a set of two scientific theories in physics: special relativity and general relativity. ... The Dirac equation is a relativistic quantum mechanical wave equation invented by Paul Dirac in 1928. ... Properties The electron is a subatomic particle. ... In chemistry, a chemical bond is the force which holds together atoms in molecules or crystals. ... The periodic table of the chemical elements, also called the Mendeleev periodic table, is a tabular display of the known chemical elements. ...

Many of the chemical and physical differences between the 6th Row (Cs-Rn) and the 5th Row (Rb-Xe) arise from the larger relativistic effects for the former. These relativistic effects are particularly large for gold and its neighbours, platinum and mercury.