A computational extension of a theory whose name begins with this term relaxes the “strong orthogonality condition” from Coulson–Fischer theory. An initial assumption in a theory whose name begins with this term that precluded the “charge-shift” family led to the failure to explain the antiaromaticity of cyclobutadiene. That theory whose name begins (10[1])with this term arose from Walter Heitler and Fritz London’s solution to the Schrödinger equation for (10[1])diatomic hydrogen, which was then expanded upon in a 1939 textbook by Linus (10[1]-5[1])Pauling. The AXE (“A-X-E”) method is used in a formalism beginning with this term that assigns labels such as “T-shaped” and “seesaw.” For 10 points, molecular (10[1])geometries are described (-5[1])using (10[1])the “electron pair repulsion” (10[2])of what outermost electrons (10[1])in an atom? ■END■ (10[1])