Molecular Geometry Lewis Structures VSEPR Theory Lewis Structures

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Molecular Geometry Lewis Structures VSEPR Theory

Molecular Geometry Lewis Structures VSEPR Theory

Lewis Structures • Count up the total number of valence electrons • Draw single

Lewis Structures • Count up the total number of valence electrons • Draw single bonds between central atom and surrounding atoms • Place remaining electrons, in pairs around appropriate atoms – Start with outer atoms • Make sure all atoms that need octets have octets • Make double bonds if necessary • Draw resonance structures (if applicable)

Lewis Structures Examples

Lewis Structures Examples

Lewis Structures • Ex: H 2 O • 1. # valence electrons • 2.

Lewis Structures • Ex: H 2 O • 1. # valence electrons • 2. Draw single bond between atoms. • 3. Place remaining electrons around appropriate atoms.

Lewis Structures • Ex: PF 3 • 1. # valence electrons • 2. Draw

Lewis Structures • Ex: PF 3 • 1. # valence electrons • 2. Draw single bond between atoms. • 3. Place remaining electrons around appropriate atoms, starting with outer atoms.

Lewis Structures • Ex: NH 41+ • 1. # valence electrons • 2. Draw

Lewis Structures • Ex: NH 41+ • 1. # valence electrons • 2. Draw single bond between atoms. • 3. Place remaining electrons around appropriate atoms, starting with outer atoms.

Lewis Structures • Ex: NO 21 • 1. # valence electrons • 2. Draw

Lewis Structures • Ex: NO 21 • 1. # valence electrons • 2. Draw single bond between atoms. • 3. Place remaining electrons around appropriate atoms, starting with outer atoms.

Lewis Structures • Check octets of each atom.

Lewis Structures • Check octets of each atom.

Lewis Structures • Nitrate can have two resonance structures because the valence electrons are

Lewis Structures • Nitrate can have two resonance structures because the valence electrons are free to move over the entire structure of the polyatomic.

Lewis Structures Formal Charge • When lewis structures have resonance structures, then the most

Lewis Structures Formal Charge • When lewis structures have resonance structures, then the most preferred resonance structure is the one with the lowest formal charge. • Take last example:

Lewis Structures Formal Charge • Formal Charge = V – N – ½(B) (valence

Lewis Structures Formal Charge • Formal Charge = V – N – ½(B) (valence electrons) – (nonbonding electrons) – ½ (bonding electrons)

Formal Charge • Formal charges should be as low as possible. • Formal charges

Formal Charge • Formal charges should be as low as possible. • Formal charges of every element that makes up the molecule should equal the overall charge of the molecule.

Formal Charge • Negative formal charges should be on the more electronegative atom (elements

Formal Charge • Negative formal charges should be on the more electronegative atom (elements closest to fluorine). • Positive formal charges should be on the less electronegative atoms.

Valence Shell Electron Repulsion Theory (VSEPR) Electron Groups Bonding Groups Lone Pairs Electron Geometry

Valence Shell Electron Repulsion Theory (VSEPR) Electron Groups Bonding Groups Lone Pairs Electron Geometry Molecular Geometry Approximate Bond Angles 2 2 0 Linear 180° 3 3 0 Trigonal Planar 120° 3 2 1 Trigonal Planar Bent <120° 4 4 0 Tetrahedral 109. 5° 4 3 1 Tetrahedral Trigonal Pyramidal <109. 5° 4 2 2 Tetrahedral Bent <109. 5°

VSEPR • Determine the lewis structure and molecular shape of: CO 2 • #

VSEPR • Determine the lewis structure and molecular shape of: CO 2 • # Valence electrons: • Lewis Structure: • Electron Geometry: • Molecular Geometry:

VSEPR • Determine the lewis structure and molecular shape of: BF 3 • #

VSEPR • Determine the lewis structure and molecular shape of: BF 3 • # Valence electrons: • Lewis Structure: • Electron Geometry: • Molecular Geometry:

VSEPR • Determine the lewis structure and molecular shape of: SO 2 • #

VSEPR • Determine the lewis structure and molecular shape of: SO 2 • # Valence electrons: • Lewis Structure: • Electron Geometry: • Molecular Geometry:

VSEPR • Determine the lewis structure and molecular shape of: CH 4 • #

VSEPR • Determine the lewis structure and molecular shape of: CH 4 • # Valence electrons: • Lewis Structure: • Electron Geometry: • Molecular Geometry:

VSEPR • Determine the lewis structure and molecular shape of: NH 3 • #

VSEPR • Determine the lewis structure and molecular shape of: NH 3 • # Valence electrons: • Lewis Structure: • Electron Geometry: • Molecular Geometry:

VSEPR • Determine the lewis structure and molecular shape of: H 2 O •

VSEPR • Determine the lewis structure and molecular shape of: H 2 O • # Valence electrons: • Lewis Structure: • Electron Geometry: • Molecular Geometry:

Valence Shell Electron Repulsion Theory (VSEPR)

Valence Shell Electron Repulsion Theory (VSEPR)

Polar Bonds • Created when electrons are drawn more closely to one of the

Polar Bonds • Created when electrons are drawn more closely to one of the atoms in the bond – The bond is polarized • Electrons are pulled toward more electronegative atoms • Electronegative atoms: atoms that strongly attract bonding electrons • Most electronegative element: Fluorine

Polar Bonds • Symbolize polar bonds with δ • Can also symbolize by

Polar Bonds • Symbolize polar bonds with δ • Can also symbolize by

Polar Bonds • Examples:

Polar Bonds • Examples:

Polar Bonds • Examples:

Polar Bonds • Examples:

Polar Bonds • Examples:

Polar Bonds • Examples:

Hybridization • Hydridization occurs to allow the atoms of the molecule to spread further

Hybridization • Hydridization occurs to allow the atoms of the molecule to spread further away from each other • S orbitals and P orbitals hybridize into sp, sp 2, and sp 3 orbitals • Anything above sp 3 does not occur because there are only 3 p orbitals – Therefore, DO NOT write sp 4 , ect. • Also, there is only one s orbital, therefore, DO NOT write s 2 p 3, ect

Hybridization • Note: We only look at hybridization in terms of the central atom.

Hybridization • Note: We only look at hybridization in terms of the central atom.

Hybridization – The Short Cut

Hybridization – The Short Cut

sp 3 Hybridization

sp 3 Hybridization

sp 2 Hybridization

sp 2 Hybridization

sp Hybridization

sp Hybridization

Determine the Hybridization of each of the following

Determine the Hybridization of each of the following

 • • • Electron Geometry Molecular Geometry (Shape) Hybridization Lewis structure (shown) Electron

• • • Electron Geometry Molecular Geometry (Shape) Hybridization Lewis structure (shown) Electron geometry (central atoms) Molecular geom. (central atoms) Hybridization of central atoms Bond angles

Electron Geometry Molecular Geometry (Shape) Hybridization • Lewis structure (shown) • Electron geometry (central

Electron Geometry Molecular Geometry (Shape) Hybridization • Lewis structure (shown) • Electron geometry (central atoms) 1. 2. 3. 4. Tetrahedral Trigonal planar Tetrahedral • Molecular geom. (central atoms) • Hybridization of central atoms • Bond angles 1 2 3 4

Electron Geometry Molecular Geometry (Shape) Hybridization • Lewis structure (shown) • Electron geometry (central

Electron Geometry Molecular Geometry (Shape) Hybridization • Lewis structure (shown) • Electron geometry (central atoms) • Molecular geom. (central atoms) 1. 2. 3. 4. Trigonal pyramidal Tetrahedral Trigonal planar Bent • Hybridization of central atoms • Bond angles 1 2 3 4

 • • Electron Geometry Molecular Geometry (Shape) Hybridization Lewis structure (shown) Electron geometry

• • Electron Geometry Molecular Geometry (Shape) Hybridization Lewis structure (shown) Electron geometry (central atoms) Molecular geom. (central atoms) Hybridization of central atoms 1. 2. 3. 4. sp 3 sp 2 sp 3 • Bond angles 1 2 3 4

 • • • Electron Geometry Molecular Geometry (Shape) Hybridization Lewis structure (shown) Electron

• • • Electron Geometry Molecular Geometry (Shape) Hybridization Lewis structure (shown) Electron geometry (central atoms) Molecular geom. (central atoms) Hybridization of central atoms Bond angles 1. 2. 3. 4. <109. 5 ~120 <109. 5 1 2 3 4