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Covalent Bonding

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Covalent Bonding Goal: Make models of covalent compounds Review Lewis diagrams for ionic compounds Draw dot structures for the ff: Iron (II) fluoride b. potassium ... – PowerPoint PPT presentation

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Title: Covalent Bonding


1
Covalent Bonding
Goal Make models of covalent compounds
  • Review Lewis diagrams for ionic compounds
  • Draw dot structures for the ff
  • Iron (II) fluoride b. potassium chloride c.
    hydrogen sulfide
  • Discussion on covalent bonding




..\Chemistry\Bonding\Covalent Bonding.ppt
  • Model Making Covalent Compounds

2
A covalent bond exists when two electrons are
shared by two non-metallic atoms.
3
COVALENT BONDING
Sharing of electrons in outer energy levels to
gain stability
4
Examples of Covalent Bonding
5
HYDROGEN
H
H
H
H
HYDROGEN MOLECULE
6
Refer to the following key for the color of the
atoms.
Element Colors Green.. Chlorine Wooden Pegs 1 inch - carbon to hydrogen or chlorine 2 inches- carbon to carbon or nitrogen/others Helical springs for multiple bonds (double or triple bonds)
Yellow Hydrogen Orange. Sodium Wooden Pegs 1 inch - carbon to hydrogen or chlorine 2 inches- carbon to carbon or nitrogen/others Helical springs for multiple bonds (double or triple bonds)
Red .. Oxygen Purple.. Potassium Wooden Pegs 1 inch - carbon to hydrogen or chlorine 2 inches- carbon to carbon or nitrogen/others Helical springs for multiple bonds (double or triple bonds)
Black .. Carbon Blue Nitrogen Wooden Pegs 1 inch - carbon to hydrogen or chlorine 2 inches- carbon to carbon or nitrogen/others Helical springs for multiple bonds (double or triple bonds)
Formula Count Atoms Draw and Color Model Dot Structure
H2 2 hydrogen atoms H H (structural formula) H H (dot structure)
Cl2 2 chlorine atoms
CH4
CCl4
7
PROPERTIES
  • low melting and boiling points

Weak IMF of attraction between simple molecules
  • generally, do not dissolve in water

8
  • generally, do not conduct electricity when
    molten or dissolved in water

do not contain ions
9
ALLOTROPHY
Elements exist in two or more forms in the same
physical state
POLYMORPHISM
10
COVALENT STRUCTURES
Simple Molecular few atoms Strong IntraM bonds Weak InterM bonds
Giant Molecular thou-sands of atoms diamond graphite plastics
11
TESTS
  1. Physical Appearance
  2. Smell (Fanning)
  3. Gentle Heating
  4. Solubility Test
  5. Conduction of electricity

12
Tetrahedral Arrangement
13
GRAPHITE
Layered structure
14
GLASSES AND CERAMICS
Super-cooled liquid
Made up of Kaolinite
15
Formula
  • Shorthand method for writing compound names.
  • Uses element symbols
  • Uses subscripts beside element symbol to indicate
    number of atoms of each element present in a
    molecule of the compound
  • Example
  • CH4
  • Carbon 1 atom
  • Hydrogen 4 atoms

16
Examples of Covalent Compounds
17
METHANE (CH4)
6C 2,4
18
AMMONIA (NH3)
7 N 2,5
19
WATER
8O 2,6
20
CARBON DIOXIDE
O C O
21
Properties of Covalent Bonds
  • Lower melting and boiling points when compared to
    ionic compounds
  • Atoms held together by weak forces.
  • Molecules in solids held closely together.
  • Generally poor conductors of electricity

22
Polar Covalent Bonds
  • Unequal sharing of electrons in covalent bond
    which causes one end of the molecule to be
    slightly positive and one end to be slightly
    negative.

23
Nonpolar Covalent Bonds
Equal sharing of valence electrons in a covalent
bond.
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