1.3: Covalent & Metallic BondsCovalent 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 BondsMolecule

–Two or more atoms joined in a specific ratio

–The smallest piece of a substance that retains its properties

1.3: Covalent & Metallic BondsRepresenting 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

–H2,O2, N2, Cl2, F2, Br2, & I2

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 BondsMetallic 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• N2O….dinitrogen monoxide

• N2H4….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”

– CO2 ….carbon dioxide

– SO3 ….sulfur trioxide