Presentation is loading. Please wait.

Presentation is loading. Please wait.

Lewis Structures & VSEPR

Published byPamela Fields Modified over 5 years ago

Similar presentations

Presentation on theme: "Lewis Structures & VSEPR"— Presentation transcript:

1 Lewis Structures & VSEPR

2 Lewis Structure Lewis Structures – shows how the _______________ are arranged among the atoms of a molecule There are rules for Lewis Structures that are based on the formation of a _______________ Atoms want to achieve a _______________ configuration

3 Octet & Duet Rules Octet Rule – atoms want to have _______________ valence electrons Duet Rule – H is the exception. It wants to be like He & is stable with only _______________ valence electrons

4 Steps for drawing Lewis Structures
Sketch a simple structure with a central atom and all attached atoms Add up all of the valence electrons for each individual atom If you are drawing a Lewis structure for a negative ion add that many electrons to create the charge If you are drawing a Lewis structure for a positive ion subtract that many electrons to create the charge

5 Steps for drawing Lewis Structures
Subtract 2 electrons for each bond drawn Complete the octet on the central atom & subtract those electrons Complete the octet on the surrounding atoms & subtract those electrons Get your final number If 0  you are done! If +  add that many electrons to the central atom If -  need to form multiple bonds to take away that many electrons

6 Bond Types ____________ bonds () – single covalent bond
____________ bonds () – occur when multiple bonds are formed Single bond – sigma Double bond – 1 sigma & 1 pi Triple bond – 1 sigma & 2 pi

7 Bond length & Strength As the number of bonds increases, the bond length ____________ The shorter the bond, the ____________ the bond

8 Examples CCl4

9 Examples HF

10 Examples NH3

11 Examples NO+

12 Exceptions to the octet rule
Sometimes the central atom violates the octet rule and has more or less than 8 valence electrons Keep using the same rules to draw Lewis Structures

13 Examples SF4

14 Examples ICl3

15 Examples XeF4

16 Examples ICl-

17 Resonance When more than one Lewis Structure can be written for a particular molecule _______________ – all possible Lewis structures that could be formed The actual structure is the _______________ of all of the structures You MUST show all structures!

18 Examples SO3

19 Examples NO2-

20 Examples NO3-

21 Formal Charge Formal charges can be used in 1 of 2 ways…
Suggest where the __________ are Help select the most __________ structure from a set of resonance structures

22 1 - Suggest where the charges are
Formal charge =

23 Example Calculate the formal charge on each element in the carbonate ion CO3 2-

24 2 - Help select the most plausible structure from a set of resonance structures
When choosing the most likely resonance structure Most likely – All formal charges are __________ Next likely – All formal charges add up to __________ Next likely – Formal charges are closest to __________ Next likely – __________ charge is on most electronegative atom

25 Example Which of the following resonance structures is most likely for CH2O and why?

26 Another Example Which is the most likely structure for N2O?

27 VSEPR Theory VSEPR Theory ________________________
The structure around a given atom is determined by minimizing the _______________ The electrons and elements bonded to the central atom want to be _______________ as possible

28 VSEPR Steps Draw the Lewis structure for the molecule
Count the total number of things that are around the central atom to determine the electron pair geometry Imagine that the lone pairs of electrons are invisible and describe the molecular shape

29 2 Electron Pairs If there are 2 things attached to the central atom, the shape is linear Bond angle = 180°

30 3 Electron Pairs If there are 3 electron pairs the shape will be trigonal planar Bond angle = 120°

31 3 electron pairs Now imagine that you have 3 electron pairs, but one is just a lone pair (invisible) what would it look like then?

32 4 electron pairs If there are 4 electron pairs, the shape will be tetrahedral Bond angle = 109.5°

33 4 electron pairs What if 1 of the electron pairs is a lone pair (invisible)? What would it look like then? Trigonal Pyramidal

34 4 electron pairs What if there are 2 lone pairs (invisible)? What would it look like then? bent

35 5 electron pairs If there are 5 electron pairs the shape will be Trigonal Bipyramidal Bond angles = 90º & 120º

36 5 electron pairs What is there is 1 lone pair (invisible) Seesaw

37 5 electron pairs What is there are 2 lone pairs (invisible) T-shaped

38 6 electron pairs If there are 6 electron pairs the shape will be octahedral Bond angle = 90°

39 6 electron pairs What if there is 1 lone pair (invisible)?
Square pyramidal

40 6 electron pairs What if there are 2 lone pairs (invisible)
Square planar

Download ppt "Lewis Structures & VSEPR"

Similar presentations

Copyright McGraw-Hill 20091 Chapter 9 Chemical Bonding II: Molecular Geometry and Bonding Theories.

Copyright McGraw-Hill Chapter 9 Chemical Bonding II: Molecular Geometry and Bonding Theories.
Molecular Geometry Lewis structures show the number and type of bonds between atoms in a molecule. –All atoms are drawn in the same plane (the paper).

Molecular Geometry Lewis structures show the number and type of bonds between atoms in a molecule. –All atoms are drawn in the same plane (the paper).
Basic Chemistry Copyright © 2011 Pearson Education, Inc. 1 Chapter 10 Structures of Solids and Liquids 10.2 Shapes of Molecules and Ions (VSEPR Theory)

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 1 Chapter 10 Structures of Solids and Liquids 10.2 Shapes of Molecules and Ions (VSEPR Theory)
Molecular shapes Balls and sticks. Learning objectives  Apply VSEPR to predict electronic geometry and shapes of simple molecules.

Molecular shapes Balls and sticks. Learning objectives  Apply VSEPR to predict electronic geometry and shapes of simple molecules.
Chapter 9 Molecular Geometry and Bonding Theories.

Chapter 9 Molecular Geometry and Bonding Theories.
Drawing Lewis Structures and VSEPR. Draw basic Lewis dot structures of atoms and compounds. Using VSEPR, predict bond shape from electron arrangement.

Drawing Lewis Structures and VSEPR. Draw basic Lewis dot structures of atoms and compounds. Using VSEPR, predict bond shape from electron arrangement.
Resonance Structures Two completely equivalent Lewis structures can be drawn for ozone, O 3. Experiment, however, shows that both bonds in ozone are equivalent.

Resonance Structures Two completely equivalent Lewis structures can be drawn for ozone, O 3. Experiment, however, shows that both bonds in ozone are equivalent.
Lewis Structures & VSEPR. Lewis Structure Lewis Structures – shows how the _______________ are arranged among the atoms of a molecule There are rules.

Lewis Structures & VSEPR. Lewis Structure Lewis Structures – shows how the _______________ are arranged among the atoms of a molecule There are rules.
Unit 7 Lewis Structures and VSEPR. Lewis Structures Show the valence electrons and bonds for a compound. 1. Draw the electron dot for each element.

Unit 7 Lewis Structures and VSEPR. Lewis Structures Show the valence electrons and bonds for a compound. 1. Draw the electron dot for each element.
(1) Covalent bonding: sharing of electron pairs by atoms

(1) Covalent bonding: sharing of electron pairs by atoms
Carvone Bucky ball Molecular Geometry Chapter 8 Part 2.

Carvone Bucky ball Molecular Geometry Chapter 8 Part 2.
Shapes of molecules & ions. VSEPR theory VSEPR - the Valence Shell Electron Pair Repulsion theory is used to obtain the shape of simple molecules and.

Shapes of molecules & ions. VSEPR theory VSEPR - the Valence Shell Electron Pair Repulsion theory is used to obtain the shape of simple molecules and.
The Structure and Bonding of IO3- An example of the use of Lewis Structures and VSEPR Theory Lecturer: Dr. Andreas Lemmerer.

The Structure and Bonding of IO3- An example of the use of Lewis Structures and VSEPR Theory Lecturer: Dr. Andreas Lemmerer.
Lewis Structures Electron-Dot-Diagrams For Molecules.

Lewis Structures Electron-Dot-Diagrams For Molecules.
Writing Lewis Structures of Molecules 1.Determine the central atom (atom in the middle) - usually is the “single” atom - least electronegative element.

Writing Lewis Structures of Molecules 1.Determine the central atom (atom in the middle) - usually is the “single” atom - least electronegative element.
Honors Shapes to Know: See Honors Packet – Linear – Trigonal Planar – Bent (with 3 e- regions and with 4) – Trigonal Pyramidal – Tetrahedral – Trigonal.

Honors Shapes to Know: See Honors Packet – Linear – Trigonal Planar – Bent (with 3 e- regions and with 4) – Trigonal Pyramidal – Tetrahedral – Trigonal.
IIIIII I. Lewis Diagrams Molecular Structure. A. Octet Rule n Remember…  Most atoms form bonds in order to have 8 valence electrons.

IIIIII I. Lewis Diagrams Molecular Structure. A. Octet Rule n Remember…  Most atoms form bonds in order to have 8 valence electrons.
The Shape of Covalent Molecules

The Shape of Covalent Molecules
Covalent Bonding Shapes VALENCE SHEELL ELECTRON PAIR REPULSION

Covalent Bonding Shapes VALENCE SHEELL ELECTRON PAIR REPULSION
Bonding – General Concepts. Shows how valence electrons are arranged among atoms in a molecule. Reflects central idea that stability of a compound relates.

Bonding – General Concepts. Shows how valence electrons are arranged among atoms in a molecule. Reflects central idea that stability of a compound relates.

Similar presentations

Ads by Google