Chapter 8: Covalent Bonding - Norwell High School€¦ · Chapter 8: Covalent Bonding 8.1 The...
Transcript of Chapter 8: Covalent Bonding - Norwell High School€¦ · Chapter 8: Covalent Bonding 8.1 The...
Chapter 8: Covalent Bonding
8.1 The Covalent Bond Main Idea: Atoms gain stability when they share electrons and
form covalent bonds Why do atoms bond? Non Metal & Metal - Non Metal & Non Metal -
Diatomic Elements - Orbital Overlap
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Lewis Dot Structures - Steps for drawing Lewis Dot Structures 1. 2. 3. 4. 5. 6. Example that only use steps 1-4
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Examples that go up to step 5 Examples that go up to step 6
Types of orbital overlap Sigma bond
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Pi Bonds
Strength of Covalent Bonds Bond Length -
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Bond Energy -
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In every chemical reaction bonds are ________________________ and new bonds are ___________________________ Energy needs to be ________________________ to break bonds, and energy is ____________________ when new bonds are formed The energy change in a reaction is the sum of these energies. If the sum of the energies is ________________________ ,energy was absorbed in the chemical reaction and the reaction is ______________________________________ If the sum of these energies is _________________________, energy was released in the chemical reaction and the reaction is __________________________
ΔH = Σ bonds broken - Σ bonds formed
Energy change in a chemical reaction = sum of the energies of the bonds broken - sum of the energies of the bonds formed
2H2 + O2 → 2H2O
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8.2 Naming Molecules Main Idea: Specific rules are used when naming binary molecular
compound, binary acids and oxyacids Naming Binary Molecular Compounds
First element name Second element + ide
use prefixes to say how many of each element (never use mono on first element)
mono = 1 hexa = 6
di = 2 hepta = 7
tri = 3 octa = 8
tetra = 4 nona = 9
penta = 5 deca = 10
Examples:
P2O5 NF3
SO2 CCl4
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Common Names for Some Molecular Compounds
H2O = water NH3 = ammonia
N2H4 = hydrazine NO = nitric oxide C6H12O6 = glucose C12H22O11 = sucrose
Names for the most common acids
HCl = hydrochloric acid
HNO3 = nitric acid H2SO4 = sulfuric acid
8.3 Molecular Structures
Main Idea: Structural formulas show the relative position of atoms within a molecule
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Advanced Lewis Dot Structures Resonance Structures - Other Examples of Resonance NO2
- O3
Exceptions to the Octet Rule 1. Incomplete Octet - Example NO2
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2. Suboctet - Coordinate Covalent Bond 3. Expanded Octet -
XeF4 ClF3 SF6
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8.4 Molecular Shapes Main Idea: The VSEPR model is used to to determine molecular
shape VSEPR - Hybridization -
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All electron domains are not bonds - some are lone pairs
To find the shape of a molecule 1. Draw the LDS.
2. Count total number of electron domains and note the number of lone pairs,
3. look on table!!
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HCN CCl4
H2S
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PBr5 SF6
ClF3 ICl4-
8.5 Electronegativity and Polarity Main Idea: A chemicals bond’s character is related to each atom’s
attraction for the electrons in the bond. Electronegativity - Polar Covalent Bond - Nonpolar Covalent Bond -
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General Rules Nonpolar Covalent bond - Polar Covalent bond - Ionic Bonds -
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Polar MOLECULE - Nonpolar MOLECULE -
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Polar or Nonpolar Flow chart CO2 H2S
O3 CH2Cl2
Properties of Covalent compounds Polar compounds are soluble in other polar compounds Nonpolar compounds are soluble in other nonpolar compounds Polar and nonpolar will not dissolve in each other (Like dissolves Like)
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What holds a solid covalent compounds together??? Covalent bonds = Intermolecular forces =
Name Between Example
Weak
Medium
Strong
Hydrogen Bonding -
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Because intermolecular forces are all much weaker than bonds, molecular compounds have __________________________ melting & boiling points. EXCEPTION - Covalent Network Solids -
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