Chemical substance identity of benzene, until the correct structure was described by Friedrich August Kekulé. Likewise, the idea of stereoisomerism – that atoms have rigid three-dimensional structure and can thus form isomers that differ only in their three-dimensional arrangement – was another crucial step in understanding the concept of distinct chemical substances. For example, tartaric acid has three distinct isomers, a pair of diastereomers with one diastereomer forming two enantiomers. An element is a chemical substance made up of a particular kind of atom and hence cannot be broken down or transformed by a chemical reaction into a different element, though it
Prefixes in Hebrew Hebrew serve multiple purposes. A prefix can serve as a conjunction, preposition, definite article, or interrogative. Prefixes are also used when conjugating verbs in the future tense and for various other purposes. These prefixes (Hebrew: תְּחִלִּית "t'chilit") often come from loanwords from English (Latin, Greek, etc...) which are especially prevalent with technical and academic terms. Other prefixes are native to Hebrew (ex. rav). When the Hebrew prefix does not line up in similarity to the English, Greek, or Latin one that is because it is of Hebrew origin. Prefixes in Hebrew There are several prefixes in the Hebrew language which