Exercises 6. trigonal planar 7. bent 8. trigonal pyramidal 9. T-shaped

Slides:



Advertisements
Similar presentations
Molecular Polarity Notes
Advertisements

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.
Polar Molecules H F electron rich region electron poor region d+ d-
Bond Polarity and Electronegativity
Molecular Polarity AP Chemistry.
 Electronegativity Electronegativity  Polarity of Bonds Polarity of Bonds  Dipole Moment Dipole Moment  Dipole Moment of Polar Covalent Bond Dipole.
Molecular Polarity Boiling point = 100 ˚C Boiling point = -161 ˚C
POLAR BONDS AND MOLECULES Ms. Withrow November 10, 2008.
POLARITY.
Chapter 16 Notes, part IV Polarity and IMFs. Types of Bonds Up until now, we have assumed that there are two types of bonds: Covalent and Ionic. This.
Aim: What are polar bonds and polar molecules?
1 Electronegativity? The ability of an atom in a molecule to attract shared electrons to itself. The ability of an atom in a molecule to attract shared.
Covalent Bonding Topics covered Homework Covalent bonding
It’s another WEINERPOINT PRESENTATION PART III Polar Bonds.
Chemistry Brodersen 2013/2014. Polarity in a molecules determines whether or not electrons in that molecule are shared equally. When determining the polarity.
1 Chapter 8 “Covalent Bonding” Ball-and-stick model.
IIIIII II. Molecular Geometry Ch. 9 – Molecular Structure.
Valence Shell Electron Pair Repulsion Theory –Electron pairs orient themselves in order to minimize repulsive forces.
Aim: What are polar bonds and polar molecules? Polar and Nonpolar Bonds There are two types of covalent bonds Nonpolar Covalent Bonds (equal share of.
Ionic & Covalent Bonding Electronegativity & Polarity.
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.
NATURE OF COVALENT BONDS 8.2 Cont’d. The difference…
Ionic, Covalent, and Metallic Bonding
Molecular Compounds Polarity.
Chapter 9 Molecular Shape.
Molecular Polarity AP Chemistry.
Intermediate bonding and bond polarity
Polarity of Molecules 301 Chemistry.
Polar Bonds and Molecules Chapter 8.4
Polarity of Covalent Bonds
Bond Polarity Electronegativity
Chapter 10 Properties of Solids and Liquids
III. Molecular Polarity (p. 183)
Polar vs. Non-Polar Molecules
Polarity of Molecules Revisited
Notes: 9.5 OBJECTIVES: Students will be able to (SWBAT)
Valence Shell Electron Pair Repulsion Theory
Covalent Bonds in Molecular Compounds
Chapter 10 Chemical Bonding II
Chapter 8 Covalent Bonding 8.4 Polar Bonds and Molecules
Molecular Polarity Chemistry.
You don’t have to go to the ends of the earth to find POLAR MOLECULES
Molecular Shapes VSEPR Theory
Polarity in Covalent Bonds
III. Molecular Polarity (p. 183)
My Name is Bond. Chemical Bond
III. Molecular Polarity
Covalent Bonds Main Concept:
Essential Question: What are polar bonds and polar molecules?
LO 6 Chemical bonding. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. The bonding pairs of electrons in covalent bonds are.
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.
Recall: Electronegativity
What are polar bonds and polar molecules?
Structure & Properties of Matter
POLAR COVALENT BONDS COVALENT= 2 NONMETALS
Ch. 6.5 Molecular Structure
Aim: How to describe the polarity of bonds and molecules
Chapter 6 -1 Bond Polarity (p. 198 – 201)
Chapter 10 Chemical Bonding II
Chapter 8 Covalent Bonding 8.4 Polar Bonds and Molecules
VI. Polarity.
2.1 Polar Covalent Bonds: Electronegativity
Unit 4 Bonding Theories.
Electronegativity and Polarity
Unit 4 Bonding Theories.
Polar versus Nonpolar.
V. Molecular Polarity (p. 183)
III. Molecular Polarity (p. 183)
Hydrogen and Chlorine:
BOND & polarity.
Presentation transcript:

Exercises 6. trigonal planar 7. bent 8. trigonal pyramidal 9. T-shaped 10. square planar

E denotes a lone pair

E denotes a lone pair

Polar bonds and polar molecules

Polar bonds and polar molecules When two identical atoms form a covalent bond, as in H2 or Cl2, each atom has an equal share of the electron pair in the bond.

Polar bonds and polar molecules When two identical atoms form a covalent bond, as in H2 or Cl2, each atom has an equal share of the electron pair in the bond. The electron density at both ends of the bond is the same because the electrons are equally attracted to both nuclei.

When different kinds of atoms combine (e. g When different kinds of atoms combine (e.g. HCl) the attractions are not equal.

When different kinds of atoms combine (e. g When different kinds of atoms combine (e.g. HCl) the attractions are not equal. In the HCl molecule the bonding electron cloud is pulled more tightly around the Cl and that end of the molecule experiences a slight buildup of negative charge.

When different kinds of atoms combine (e. g When different kinds of atoms combine (e.g. HCl) the attractions are not equal. In the HCl molecule the bonding electron cloud is pulled more tightly around the Cl and that end of the molecule experiences a slight buildup of negative charge. In HCl electron transfer is incomplete. The electrons are still shared, but unequally.

When different kinds of atoms combine (e. g When different kinds of atoms combine (e.g. HCl) the attractions are not equal. In the HCl molecule the bonding electron cloud is pulled more tightly around the Cl and that end of the molecule experiences a slight buildup of negative charge. In HCl electron transfer is incomplete. The electrons are still shared, but unequally. The charges on either end of the molecule are less than full +1 (on H) and -1 (on Cl) – they are partial charges indicated by a Greek letter delta δ.

When different kinds of atoms combine (e. g When different kinds of atoms combine (e.g. HCl) the attractions are not equal. In the HCl molecule the bonding electron cloud is pulled more tightly around the Cl and that end of the molecule experiences a slight buildup of negative charge. In HCl electron transfer is incomplete. The electrons are still shared, but unequally. The charges on either end of the molecule are less than full +1 (on H) and -1 (on Cl) – they are partial charges indicated by a Greek letter delta δ. H Cl δ+ δ-

The situation for H2, compared with F2, and HF.

A bond that carries partial positive and negative charges at opposite ends is called a polar bond.

A bond that carries partial positive and negative charges at opposite ends is called a polar bond. The polar bond in HCl results because the bond has poles of opposite charge at either end: the molecule is said to be a dipole.

A bond that carries partial positive and negative charges at opposite ends is called a polar bond. The polar bond in HCl results because the bond has poles of opposite charge at either end: the molecule is said to be a dipole. The extent of the polarity of a molecule is expressed quantitatively through its dipole moment.

Dipole moment: A measure of the charge separation in a molecule: the product of the charge and the distance between the charges:

Dipole moment: A measure of the charge separation in a molecule: the product of the charge and the distance between the charges: where is the dipole moment, Q is the charge, and r is the separation distance.

Dipole moment: A measure of the charge separation in a molecule: the product of the charge and the distance between the charges: where is the dipole moment, Q is the charge, and r is the separation distance. When there are a number of different charges, it is necessary to sum over all the charges (we will not deal with this case).

Dipole moment: A measure of the charge separation in a molecule: the product of the charge and the distance between the charges: where is the dipole moment, Q is the charge, and r is the separation distance. When there are a number of different charges, it is necessary to sum over all the charges (we will not deal with this case). By convention Q is taken to be the positive charge involved.

Example: If the separation is 1. 00 Å (1 Example: If the separation is 1.00 Å (1.00 x 10-8 cm) and the charge involved is the full electronic charge, calculate the dipole moment.

Example: If the separation is 1. 00 Å (1 Example: If the separation is 1.00 Å (1.00 x 10-8 cm) and the charge involved is the full electronic charge, calculate the dipole moment. The magnitude of the electronic charge is 1.602 x 10-19 C. (The unit of charge in the SI system is the coulomb, abbreviated C).

Example: If the separation is 1. 00 Å (1 Example: If the separation is 1.00 Å (1.00 x 10-8 cm) and the charge involved is the full electronic charge, calculate the dipole moment. The magnitude of the electronic charge is 1.602 x 10-19 C. (The unit of charge in the SI system is the coulomb, abbreviated C).

Example: If the separation is 1. 00 Å (1 Example: If the separation is 1.00 Å (1.00 x 10-8 cm) and the charge involved is the full electronic charge, calculate the dipole moment. The magnitude of the electronic charge is 1.602 x 10-19 C. (The unit of charge in the SI system is the coulomb, abbreviated C). = 1.602 x 10-19 C 1.00 x 10-8 cm = 1.60 x 10-29 Cm

Dipole moments are usually expressed in debye units, abbreviation D: 1 D = 3.336 x 10-30 Cm

The dipole moment in the example is = 1.60 x 10-29 Cm = 4.80 D Dipole moments are usually expressed in debye units, abbreviation D: 1 D = 3.336 x 10-30 Cm The dipole moment in the example is = 1.60 x 10-29 Cm = 4.80 D

The dipole moment in the example is = 1.60 x 10-29 Cm = 4.80 D Dipole moments are usually expressed in debye units, abbreviation D: 1 D = 3.336 x 10-30 Cm The dipole moment in the example is = 1.60 x 10-29 Cm = 4.80 D Note in this example, we have total charge separation (the electron is not shared) so 4.80 D corresponds to an ionic bond.

The dipole moment in the example is = 1.60 x 10-29 Cm = 4.80 D Dipole moments are usually expressed in debye units, abbreviation D: 1 D = 3.336 x 10-30 Cm The dipole moment in the example is = 1.60 x 10-29 Cm = 4.80 D Note in this example, we have total charge separation (the electron is not shared) so 4.80 D corresponds to an ionic bond. Covalently bonded diatomic molecules will have smaller dipole moments (in general).

Key point: In some molecules, the effects of the polar bonds cancel, and even though the individual bonds in the molecule may be polar, the molecule as a whole is nonpolar.

Key point: In some molecules, the effects of the polar bonds cancel, and even though the individual bonds in the molecule may be polar, the molecule as a whole is nonpolar. Example: carbon dioxide, CO2

Key point: In some molecules, the effects of the polar bonds cancel, and even though the individual bonds in the molecule may be polar, the molecule as a whole is nonpolar. Example: carbon dioxide, CO2 O C O

Key point: In some molecules, the effects of the polar bonds cancel, and even though the individual bonds in the molecule may be polar, the molecule as a whole is nonpolar. Example: carbon dioxide, CO2 O C O

Key point: In some molecules, the effects of the polar bonds cancel, and even though the individual bonds in the molecule may be polar, the molecule as a whole is nonpolar. Example: carbon dioxide, CO2 O C O

Key point: In some molecules, the effects of the polar bonds cancel, and even though the individual bonds in the molecule may be polar, the molecule as a whole is nonpolar. Example: carbon dioxide, CO2 O C O Arrows points in the direction of negative charge: these represent the bond dipoles.

The molecular dipole moment is the vector sum of the two bond dipoles The molecular dipole moment is the vector sum of the two bond dipoles. For CO2, this sum = 0.

The molecular dipole moment is the vector sum of the two bond dipoles The molecular dipole moment is the vector sum of the two bond dipoles. For CO2, this sum = 0. So the dipole moment for the molecule is zero, and hence the molecule is nonpolar.

The molecular dipole moment is the vector sum of the two bond dipoles The molecular dipole moment is the vector sum of the two bond dipoles. For CO2, this sum = 0. So the dipole moment for the molecule is zero, and hence the molecule is nonpolar. For this case the bond dipoles have the same magnitude, but they point in opposite directions, and therefore cancel.

Math Aside: Resolving a vector into components.

Math Aside: Resolving a vector into components. Component of in the x direction is

Math Aside: Resolving a vector into components. Component of in the x direction is Component of in the y direction is

Example: BF3, is it polar or nonpolar?

Example: BF3, is it polar or nonpolar Example: BF3, is it polar or nonpolar? To show that the molecule is nonpolar, we would need to prove:

Example: BF3, is it polar or nonpolar Example: BF3, is it polar or nonpolar? To show that the molecule is nonpolar, we would need to prove:

Example: BF3, is it polar or nonpolar Example: BF3, is it polar or nonpolar? To show that the molecule is nonpolar, we would need to prove: That is, the components of the dipole moment of the molecule in the x, y, and z directions must each be zero.

All four atoms are in the x–y plane and the z direction is perpendicular to the plane.

All four atoms are in the x–y plane and the z direction is perpendicular to the plane. Each FBF angle is exactly 120o.

All four atoms are in the x–y plane and the z direction is perpendicular to the plane. Each FBF angle is exactly 120o. There are three bond dipoles, each of strength .

All four atoms are in the x–y plane and the z direction is perpendicular to the plane. Each FBF angle is exactly 120o. There are three bond dipoles, each of strength . The z-direction:

All four atoms are in the x–y plane and the z direction is perpendicular to the plane. Each FBF angle is exactly 120o. There are three bond dipoles, each of strength . The z-direction:

All four atoms are in the x–y plane and the z direction is perpendicular to the plane. Each FBF angle is exactly 120o. There are three bond dipoles, each of strength . The x-direction:

All four atoms are in the x–y plane and the z direction is perpendicular to the plane. Each FBF angle is exactly 120o. There are three bond dipoles, each of strength . The y-direction:

Conclusion: BF3 is a nonpolar molecule.

Example: water.

Example: water. What is the correct shape?

Example: water. What is the correct shape?

Example: water. What is the correct shape?

Example: water (bent shape)