1.3: covalent & metallic bonds covalent bonds –form when atoms share 1 or more pairs of e- 2...
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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