valence (n.) Look up valence at Dictionary.com
early 15c., "extract, preparation," from Latin valentia "strength, capacity," from valentem (nominative valens) "strong, stout, vigorous, powerful," present participle of valere "be strong" (from PIE root *wal- "to be strong"). Chemistry sense of "relative combining capacity of an element with other atoms when forming compounds or molecules" is recorded from 1884, from German Valenz (1868), from the Latin word. Related: Valency.