The chemical compounds

Chemical elements are formed by a single type of atom (Na, K, O ₂ , N ₂ ), while compounds are formed by the union of two or more types of atoms. Water is a chemical compound made up of two hydrogen atoms and one oxygen (H ₂ O). Carbon dioxide is made up of one carbon atom and two oxygen (CO ₂ ). Chemical compounds are represented by the symbols of the elements that form them accompanied by subscripts that indicate the proportion in which these elements participate.