Transcript Chemical Bonds foldable

Compounds & Bonds –
Unit 5
Why do atoms bond to form
compounds?
How are bonds formed?
How do we represent compounds
(names and formulas)?
Bonding Essentials
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Bonds are formed when valence electrons are
gained, lost or shared by atoms
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There are 3 major types of bonds
 Ionic, Covalent, Metallic
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Compounds are 2 or more atoms bonded together,
with different properties than their elements.
Warm-up: What type of bonds
are created with:
Ionic, Covalent (non-polar or polar)
Use the PT (for electronegativity trends)
 Cr and Fe
 Rb and Br
 Cl and Cl
 H and F
 Ba and I
 S and S
Covalent Bonds – Strength
What is the
Relationship between:
- Bond energy &
Bond length
- Bond energy &
Number of bonds
Intermolecular forces
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What holds the separate covalent bonds
together?
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Lewis structures:
A different way
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Practice Lewis structures (electron dot)
Structural formula (shows bonds with lines)
Introduce shape of compounds
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VSEPR
Determine polarity
Identify diatomic molecules (7)
Electronic cereal:
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Start with diatomic molecules
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1.
2.
3.
2 atoms of the same element (7)
Rules to follow: Make every compound
Use different colors for each atom
Show how each atom contributes electrons
to the bond and the lone pairs
Determine shape & polarity
1.
Polarity is?
Properties of Ionic Compounds
Structure:
Crystalline solids (always)
Hardness
Hard (like rocks)
Melting point:
High
Boiling Point:
High
Electrical
Conductivity:
Solubility in
water:
No : if solid
Yes: if melted or dissolved
Generally soluble
Properties of Covalent
Compounds (molecules)
Gas, Liquid or “soft”
solid
Hardness
Low
Melting point
Low to medium
Boiling Point
Low to medium
Electrical conductivity No
Soluble in water
Only if polar covalent
compound
Structure
Properties of Metallic Solids
Structure
Hardness
Solid
Medium (malleable,
ductile)
Melting point
Medium to high
Boiling point
Medium to high
Electrical conductivity Yes
Soluble in water
No
Opposites Attract
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Find ions that can bond
Write the symbol and the charge
Write the new compound formed by
combining the ions.
Name the compound.
Write at least 15 compounds.
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Ten should include subscripts.
Bond type
Compound
(names & formulas)
Properties
(physical and chemical)
Foldable – Front cover
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Covalent Bonds
form Molecules
(Covalent compounds)
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Ionic Bonds
form Ionic Compounds
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Metallic Bonds
form Metallic Solids
Page 1
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Covalent bond
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Picture
Type of atoms
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Ionic bond
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Picture
Type of atoms
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Metallic bond
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Picture
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Electrons are:
EN difference
Electrons are:
EN difference
Type of atoms
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Electrons are:
Page 2
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Molecules (covalent
compounds)
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Properties of molecules
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Properties of Ionic
compounds
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Properties of metallic
solids
Lewis structure of water
Ionic Compounds
(salts)
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Picture
Metallic solid
Page 3
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Common examples of
molecules
Names & formulas
- Binary molecules
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Common examples of
ionic compounds
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Binary ionic compounds
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Brass
Pewter
Sterling silver
Stainless steel
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Common examples of
metallic solids
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Page 4 – names & formulas
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Molecules
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Ionic Compounds
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Diatomic molecules
Acids
Transition metals
Polyatomic ions
Metallic solids
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Bronze
Gold
Lewis Diagrams
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Count and add the valence electrons for each atom.
Put C as the central atom (or element with with
lowest electronegativity).
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Hydrogen is never the central atom
Place 2 electrons for each bond between 2 atoms.
Arrange the other electrons evenly around the atoms
to satisfy the octet rule.
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Duet rule for H.
If there are not enough electrons, make double or triple
bonds.
Lewis Diagrams
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Valence Shell
Electron Pair
Repulsion
 VSEPR
This means: