Chemical Bonding Atoms and Valence Electrons

Chemical Bond: the force of attraction that holds atoms together as a result of the rearrangement of electrons between them Valence electrons, the electrons in the outer most shell of an atom, are the electrons that have the highest energy Valence electrons are involved in chemical bonding The number of valence electrons in each atom determines the chemical properties, thus determining its reactivity

Atoms tend to be more stable if they have 8 valence electrons. Valence electrons are transferred from one atom to another during chemical bonding Electron Dot Diagrams show only the # of Val. e-

Remember: Group indicates # of Val. e- Group 18 – The Nobel Gases, all have 8 Val. e- * Atoms with 8 valence electrons are stable and do not react easily Group 17 – The Halogens, all have 7 Val. e- * Atoms with 7 valence electrons react easily, they only need 1 more to be stable Metals – React by losing their valence electrons Nonmetals – React by gaining or “sharing” electrons

Compound - two or more elements held together by chemical bonds (compound bound) Examples: Water H 2 0 Carbon Dioxide CO 2

Types of Chemical Bonds 1.Ionic Bonds Metal bonds to Nonmetal  Ionic Bonds for Ions  Ion: an electrically charged atom

2.Covalent Bonds Nonmetal bonds with Nonmetal