So-called “designer solvents” named for this term are functionalized to make them task-specific. In the Debye–Hückel limiting law, the natural logarithm of the mean activity coefficient is proportional to the square root of a quantity named for this term. The quantity (10[1])“square root of 12 over 12 minus coordination number, all minus one” defines the critical value of the ratio in compounds described by this term written as “r-sub-C over r-sub-A.” This term names room-temperature liquids such as BMIM-PF6 and EMIM. (10[1])Compounds described by this term are described by Pauling’s five rules. The Born–Haber cycle calculates the lattice energy of compounds (-5[1])described by this term. (10[1])For 10 points, name this term that describes bonds between two oppositely (10[1])charged (10[1])species (10[2])such as sodium and chloride. (10[1])■END■ (10[1])