Chapter 8 Chemical Bonding Pages 224 - 249 Section 1

Combining Atoms Through Chemical Bonding Chemical bonding is the joining of atoms to form new substances. An interaction that holds atoms together is called a chemical bond.

Electron Number and Organization Atomic number = Protons = Electrons Electrons are organized in energy levels Most atoms form bonds using only the electrons in the outer energy level Outer energy level electrons are valence electrons This chlorine atom has 7 valence electrons

Valence Electrons & The Periodic Table Elements are grouped in vertical columns and have similar properties Group numbers help you determine the number of valence electrons

To Bond or Not To Bond The number of valence electrons in the outer most energy level of an atom determines if an atom will form bonds. Atoms tend to bond with other atoms so that they can fill or complete their outer most energy level with eight electrons. H, He and Li only need two outer electrons to be full. Noble gases already have a full outer energy level and tend not to bond with other atoms.

Let’s Try It! LAB: Eggshell Electrons