valance / valence are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
valance: NA
valence: (noun) (biology) a relative capacity to unite or react or interact as with antigens or a biological substrate. (noun) (chemistry) a property of atoms or radicals; their combining power given in terms of the number of hydrogen atoms (or the equivalent).
valance: NA
valence: v·EY·l·ah·n·s
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)