CHEM 1210 Lecture Notes - Lecture 3: Group 8 Element, Valence Electron, Octet Rule

• School: Ohio University
• Department: Chemistry
• Course: CHEM 1210
• Professor: Tangonan

Document Summary

Under standard conditions, the noble gases (group 8 elements) are odorless, colorless, monatomic gases with very little (if any) chemical reactivity. In 1916, gilbert n. lewis pointed out that this a lack of chemical reactivity indicates a high degree of stability of their electron configuration (a full outer shell) Octet rule: the tendency of group 1a-7a elements to react in ways that achieve an electron configuration of eight valence electrons (like the noble gases) An atom that loses one or more electrons becomes a positively charged ion called a cation (ex: na+) An atom that gains one or more electrons becomes a negatively charged ion called an anion (ex: cl-) Ex: sodium: group 1 = 1 valence electron. In losing one electron, a sodium atom forms a sodium ion. It gains the same electron configuration as the noble gas neon. Ex: chlorine: group 7 = 7 valence electrons. In gaining one electron a chlorine atom forms a chloride ion.