1.3: Covalent & Metallic Bonds Covalent Bonds –Form when atoms share 1 or more pairs of e- 2 nonmetals don’t transfer e- to fill the outer most energy level –Water, sugar, oxygen, wood –Low mp and bp; brittle as solids –Formed by nonmetals

1.3: Covalent & Metallic Bonds Molecule –Two or more atoms joined in a specific ratio –The smallest piece of a substance that retains its properties

1.3: Covalent & Metallic Bonds Representing Molecules –Models Show all electrons and energy levels –Electron Dot Diagrams Show only the valence electrons (outer energy level)

1.3: Covalent & Metallic Bonds Electron Dot Diagram O C Show only the valence e- for the atoms

1.3: Covalent & Metallic Bonds Molecules –The smallest particle into which a covalently bonded compound can be divided & still be the same compound

1.3: Covalent & Metallic Bonds Diatomic Molecules –The simplest molecules –Made from 2 atoms of the same elements –H 2,O 2, N 2, Cl 2, F 2, Br 2, & I 2

1.3: Covalent & Metallic Bonds Complex (Macro) Molecules –Carbon is the base element in many complex compounds –Soap, plastic, proteins made from many atoms sharing e- –“Organic Chemistry” C, H, O compounds

1.3: Covalent & Metallic Bonds Metallic Bonds –Formed by the attraction between positively charged metal ions and the e- in the metal –Outermost energy levels overlap

1.3: Covalent & Metallic Bonds Metallic Bonds (cont) –Positive metal ions are fixed –Electrons are free to move around the cations –A “sea of electrons” where the electrons are shared with all metal cations

1.3: Covalent & Metallic Bonds Properties of Metals –Conductivity Copper, gold, silver, etc. allow electrons to move freely –Malleable Can be hammered into sheets –Ductile Can be drawn into thin wire

1.3: Covalent & Metallic Bonds Bend, but not Break –Metallic bonds occur in many directions –Numerous electrons in the metal hold the cations together, thus keeping the bond intact

Naming Covalent Compounds (2.2 in text) Formulas for Covalent Compounds –A covalent compound is made of 2 or more nonmetals –Prefixes are used to indicate the number of atoms of each element in the chemical formula N 2 O….dinitrogen monoxide N 2 H 4 ….dinitrogen tetrahydride

Naming Covalent Compounds (2.2 in text) Prefixes you must know mono- 1 hexa- 6 di- 2 hepta- 7 tri- 3 octa- 8 tetra- 4 nona- 9 penta- 5 deca- 10

Naming Covalent Compounds (2.2 in text) Formulas for Covalent Compounds –If the there is only 1 atom of the first nonmetal in a covalent compound, we do not usually use the prefix “mono” –CO 2 ….carbon dioxide –SO 3 ….sulfur trioxide