Molecular Structure Molecular Geometry.

Slides:

Advertisements

Similar presentations

How is VSEPR theory used to predict molecular structure?

Advertisements

Chemical Bonding and VSEPR L. Scheffler IB Chemistry 1-2 Lincoln High School 1.

Drawing Lewis structures

Structure of molecules Objectives: To understand molecular structure and bond angles To learn to predict molecular geometry from the number of electron.

SHAPES OF MOLECULES. REMINDER ABOUT ELECTRONS  Electrons have negative charges  Negative charges “repel” each other  In molecules, electrons want to.

Molecular Shape The Geometry of molecules. Molecular Geometry nuclei The shape of a molecule is determined by where the nuclei are located. nuclei electron.

Ch 6.5 Molecular Geometry.

Lecture 11 - VSEPR Theory, Molecular Shape 5 Base e - pair geometries will predict 13 Molecular geometries STEPS FOR SUCCESS: 1.draw Lewis 2. bonding pairs.

MOLECULAR GEOMETRY VSEPR ACTIVITY. CARBON DIOXIDE Chemical formula: CO 2 # of atoms bonded to central atom: 2 # of lone pairs on central atom: 0 What.

Molecular Shapes Chapter 6 Section 3. Molecular Structure It mean the 3-D arrangement of atoms in a molecule Lewis dot structures show how atoms are bonded.

Carvone Bucky ball Molecular Geometry Chapter 8 Part 2.

Chapter 8 Shape of molecules. VSEPR- Stands for: Valence-shell electron pair repulsion theory. States that pairs of valence e- arrange as far apart as.

VSEPR Theory Valence Shell Electron Pair Repulsion.

8.4 DETERMINING MOLECULAR SHAPES. THE MODEL WE WILL USE TO DETERMINE MOLECULAR SHAPE IS CALLED _________ (V_____________ S_________ E_____________ P________.

Polarity Chapter 6.1. Review A covalent bond is formed between two non-metals. Electrons are shared. Orbitals are overlapping.

Molecular Geometry VSEPR Theory.

IIIIII Molecular Geometry Molecular Structure. A. VSEPR Theory  Valence Shell Electron Pair Repulsion Theory  Electron pairs orient themselves so that.

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

IIIIII II. Molecular Geometry Ch. 9 – Molecular Structure.

Covalent Bonding Shapes VALENCE SHEELL ELECTRON PAIR REPULSION

Predict the geometry of the molecule from the electrostatic repulsions between the electron (bonding and nonbonding) pairs. Valence shell electron pair.

Valence Shell Electron Pair Repulsion Theory –Electron pairs orient themselves in order to minimize repulsive forces.

IIIIII I. Lewis Diagrams (p ) Ch. 6 – Molecular Structure.

Section 8.3 Bonding Theories. VSEPR Theory Electron dot structures fail to reflect the three dimensional shapes of the molecules. VSEPR Valence Shell.

The Shapes of Molecules Or in Big Scientific Words “MOLECULAR GEOMETRY”

I can #2 I can draw a Lewis structure. Rules for Lewis Structures 1. total number of valance electrons 2. central atom –Always C, Never H, Rarely O, or.

Molecular Shapes. VSEPR Valence Shell Electron Pair Repulsion The main idea is that electrons don’t like to hang around near each other because they repel.

Ch-8 Part II Bonding: General Concepts. Molecular Geometry and Bond Theory In this chapter we will discuss the geometries of molecules in terms of their.

VSEPR Notes & Lab GT Chemistry 12/15/14. Drill Draw Lewis structures for –CH 3 Br –NH 3 –HCl (that’s hydrogen chloride, not carbon/iodine) –AlF 3 HW:

VSEPR Theory Valence Shell Electron Pair Repulsion.

6.8 Shapes and Polarity of Molecules

Chapter 6 The Shape of Molecules.

Chapter 8 Covalent Bonding 8.3 Bonding Theories

Molecular Geometry (VSEPR)

Ch. 6 – Molecular Structure

Ch. 6.5 Bonding Theories Molecular Geometry.

Valence shell electron pair repulsion (VSEPR) model:

MOLECULAR GEOMETRY Bonding Unit.

II. Molecular Geometry (p. 183 – 187)

The VSEPR Theory Section 4.3.

Valence Shell Electron Pair Repulsion Theory

Bonding Unit Part B) Structures and Shapes

Ch. 6 – Molecular Structure

Important Information:

Molecular Structure Molecular Geometry.

Chapter 8 Covalent Bonding 8.3 Bonding Theories

Drawing Molecules and Shapes

Types of Covalent Bonds

All shapes came from Shapes of Molecules All shapes came from

Chapter 8 Covalent Bonding 8.3 Bonding Theories

Nonpolar Covalent Bonds

Valence Shell Electron Pair Repulsion

Although all covalent bonds involve a sharing of one or more pairs of electrons between bonding atoms, most of the time this sharing is not equal. One.

Molecular Structure and Shape

Valence Shell Electron Pair Repulsion Theory

Nonpolar Covalent Bonds

Molecular Structure II. Molecular Geometry.

Chapter 10 Chemical Bonding II

II. Molecular Geometry (p. 183 – 187)

Warm up Draw lewis structures for the compounds below: CF4 BF3 CO2.

Molecular Geometry.

Molecular Shapes VSEPR Model

II. Molecular Geometry (p. 183 – 187)

II. Molecular Geometry (p. 183 – 187)

Drawing Molecules and Shapes

VSEPR Theory Atoms in a molecule try to spread out from one another as much as possible.

Presentation transcript:

Molecular Structure Molecular Geometry

VSEPR theory Valence-Shell Electron-Pair Repulsion Theory: Because electron pairs repel, molecules adjust their shapes so that valence electron pairs are as far apart as possible

Vsepr continued… Types of electron pairs Bonding Pairs: Electrons that form bonds Lone (unshared) Pairs: Electrons that are nonbonding; no atom trying to bond. These are held closer to the atom they are associated with than bonding pairs. Lone Pairs Repel More Strongly Than Bonding Pairs!

Lone pair effects on bond angles In methane there are no lone pair electrons so in the tetrahedral shape the bond angles are the expected 109.50. In the ammonia molecule there is one lone pair. Since it has a stronger repulsion is closes the bond angle a little to 1070 In the water molecule there are 2 lone pairs each having greater repulsion causing the angle to close even more to 104.50 angle.

Determining Molecular Shape Draw the Lewis Diagram Count up electron pairs on central atom. double/triple bonds = ONE pair Shape is determined by the # of bonding pairs and lone pairs. Be Familiar With the Common Shapes & Their Bond Angles See p.10 in CRM

Common shape-Linear Beryllium Hydride 2 total electron pairs 2 bonding pairs 0 lone pairs Beryllium does not follow the octet rule. Beryllium is complete with 4 valence electrons Carbon dioxide Carbon does follow the octet rule fulfilling it through two double bonds in this case

Common shape-trigonal planar Boron Hydride 3 total electron pairs 3 bonding pairs 0 lone pairs Boron is also an exception to the octet rule. Boron is complete with 6 valence electrons Formaldehyde 4 total electron pairs 4 bonding pairs Carbon does follow the octet rule, which is fulfilled by the double bond.

Common Shape - Bent Ozone Generally O would have two bonding pairs which is seen by the upper O, the other two adjust so that all three can obey the octet rule Water 4 total pairs 2 bonding pairs 2 lone pair

Common shape-tetrahedral Methane 4 total pairs 4 bonding pairs 0 lone pairs

Common shape-trigonal pyramidal Ammonia 4 total pairs 3 bonding pairs 1 lone pair

Common shape- trigonal bipyramidal Phosphorous pentachloride 5 total pairs 5 bonding pairs 0 lone pairs

Common shape - octahedral Sulfur Hexafluoride 6 total pairs 6 bonding pairs 0 lone pairs

Molecular Structure Molecular Polarity

Dipole Moment Direction of the polar bond in a molecule Arrow points toward the more electronegative atom.

Determining Molecular polarity Depends on - dipole moments - molecular shape

Polar & Nonpolar molecules Nonpolar Molecules - dipole moments are symmetrical and cancel out Polar Molecules - dipole moments are asymmetrical and don’t cancel

Polar Molecules Therefore, polar molecules have… - asymmetrical shape (lone pairs) or - asymmetrical atoms