Honors Chemistry Lewis Structures and VSEPR Theory.

Slides:

Advertisements

Similar presentations

Advertisements

Molecular Geometries and Isomers

8.1 Chemical Bonds, Lewis Symbols, and the Octet Rule

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

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 Geometry 2-2 Ch. 6 – Molecular shape. Molecules are three-dimensional objects that occupy a three- dimensional world; In general, only the smallest.

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.

Drawing Lewis Structures and VSEPR. Draw basic Lewis dot structures of atoms and compounds. Using VSEPR, predict bond shape from electron arrangement.

Chemical Bonds.

Wednesday, Feb. 19 th : “A” Day Thursday, Feb. 20 th : “B” Day Agenda  Collect homework: pg. 198: 1-14  Collect lab: “Nonmetal Reaction”  Sec. 6.1.

Drawing and Naming Molecules Lewis Dot Structures and Multiple Bonds.

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.

Types of chemical bonds Bond: Force that holds groups of two or more atoms together and makes the atoms function as a unit. Example: H-O-H Bond Energy:

1 For ions we must adjust the number of electrons available, A: Add one e - to A for each negative charge Subtract one e - from A for each positive charge.

Chemical Bonds. Forming Chemical Bonds  The force that holds two atoms together is called a chemical bond.  The valence electrons are the electrons.

Types of chemical bonds Bond: Force that holds groups of two or more atoms together and makes the atoms function as a unit. Example: H-O-H Bond Energy:

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

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.

Drawing Lewis Structures and VSEPR A Tutorial on Writing Lewis Dot Structure.

Notes #10 Lewis Structures. Valence Electrons Valence electrons are those electrons in the highest principle energy level (n). Only these outer electrons.

+ Bonding Part III Unit 5: Bonding Mrs. Callender VS E P R.

Molecular Geometry And Polarity.

Chapter 8 Covalent Bonding. The Covalent Bond Atoms will share electrons in order to form a stable octet. l Covalent bond : the chemical bond that results.

1 Covalent bonding. 2 How does H 2 form? l The nuclei repel ++

Chapter 6 Chapter 6 Representing Molecules 1.

Section 12.3 Lewis Structures 1.To predict the electron arrangement in molecules 2.To learn to write simple Lewis structures 3.To learn to write Lewis.

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.

CHAPTER 6: COVALENT COMPOUNDS Section 1: Covalent Bond Section 2: Drawing and Naming Section 3: Molecular Shapes.

Chapter 4 Covalent Compounds.

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

Lewis Symbols and the Octet Rule Electron Dot Symbols convenient way of showing the valence electrons of atoms. Consists of the chemical symbol and one.

Section 3.3 – Part A Pg Objective: 1) Apply VSEPR theory to predict molecular shapes.

Drawing Lewis Structures and predicting formulas of covalent compounds.

AP Chapter 7 Covalent Bonding Lewis Structures A Lewis structure shows the distribution of outer (valence) electrons in an atom, molecule, or polyatomic.

Molecular Shape and Polarity The Importance of Geometry in Determining Physical Properties.

9 - 1 Molecular Geometry Molecules have different shapes (geometries) depending on the type of atoms making it up and the number of electron pairs present.

Section 12.1 Characteristics of Chemical Bonds 1.To learn about ionic and covalent bonds and explain how they are formed 2.To learn about the polar covalent.

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

 UNIT 4 Bonding and Stereochemistry. Stable Electron Configurations  All elements on the periodic table (except for Noble Gases) have incomplete outer.

CHAPTER 4 Covalent Molecules General, Organic, & Biological Chemistry Janice Gorzynski Smith.

Chapter 6 Chemical Bonding. Bonding Theory and Electronegativity Atoms want to achieve noble gas configuration- 8 valence e- Some elements have stronger.

Section 8.2 The Nature of Covalent Bonding. The Octet Rule Atoms share electrons so they have a filled valence shell. Atoms share electrons so they have.

Resonance  A molecule or polyatomic ion for which 2 or more dot formulas with the same arrangement of atoms can be drawn is said to exhibit RESONANCE.

Lewis Structures & VSEPR Meyer Lewis Structures Lewis Structure – Picture of a molecule – Uses lines to indicate chemical bonds – Uses dots to indicate.

VSEPR THEORY Chemistry. Polyatomic Ions  Ions that are composed of covalently bound atoms.  Add or subtract electrons for charge when finding total.

Molecular Geometry. It’s all about the Electrons Electrons decide how many bonds an atom can have They also decide the overall shape of the molecule OPPOSITES.

Covalent Compounds. Resonance Resonance structures are those that occur when it is possible to draw two or more valid electron dot structures that have.

 LEM › A molecule is composed of atoms that are bound together by sharing pairs of e- using the atomic orbitals of the bound atoms. › Lone pairs › Bonding.

Chemistry Unit 4 Chapter 8.  Molecule  A neutral group of atoms joined together by covalent bonds  Molecular Compound  Tend to have lower melting.

Chapter 7 Bonding. What is a Bond? l A force that holds atoms together. l We will look at it in terms of energy. l Bond energy is the energy required.

Chemical bonds. Bonding, the way atoms are attracted to each other to form molecules, determines nearly all of the chemical properties we see. Chemical.

University of Louisiana at Lafayette

Types of chemical bonds

4.1 Introduction to Covalent Bonding

Chapter 8 Section 3 Molecular Structures.

Chapter 10 Molecular Structure: Solids and Liquids

Drawing Molecules and Shapes

Chapter 10 Properties of Solids and Liquids

Molecular Structure and Shape

Formation of Compounds from atoms

Valence Shell Electron Pair Repulsion

I. Lewis Diagrams (p. 202 – 213) Lecture 2.

I. Lewis Diagrams (p. 202 – 213) Lecture 2.

Formation of Compounds from atoms

Drawing Molecules and Shapes

Molecular Shapes.

Presentation transcript:

Honors Chemistry Lewis Structures and VSEPR Theory

Lewis Structures A Lewis structure shows the distribution of outer (valence) electrons in an atom, molecule, or polyatomic ion. Unshared electrons are shown as dots Bonds are shown as straight lines

In H 2 O and HF, as in most molecules and polyatomic ions, nonmetal atoms except H are surrounded by eight electrons, an octet. In this sense, each atom has a noble gas structure Lewis structures are written following a stepwise procedure

A) Rules for writing Lewis Structures (single bonds) 1.Count valence electrons available. (use group number for nonmetals!) 2.Add electrons to take into account negative charge

OCl - ion: = 14 valence e - CH 3 OH molecule: 4 + 4(1) + 6 = 14 valence e - SO 3 -2 ion: 6 + 3(6) + 2 = 26 valence e -

Draw skeleton structure, using single bonds Note that carbon almost always forms four bonds. Central atom is written first in formula, terminal atoms are most often H, O, or a halogen

3. Deduct two electrons for each single bond in the skeleton OCl - ion: 14 – 2 = 12 valence e - left CH 3 OH molecule: 14 – 10 = 4 valence e - left SO 3 -2 ion: 26 – 6 = 20 valence e- left

4. Distribute these electrons to give each atom a noble gas structure, if possible

Examples of central atom POCl 3 P is central atom SO 4 -2 S is central atom SO 3 -2 S is central atom PO 4 -3 P is central atom SCl 2 S is central atom

Draw Lewis Dot Structure Ethane C 2 H 6 Check answer on page 167

B. Too few electrons; form multiple bonds Structure of NO 3 - ion? Number of valence electrons = ? = 24 Go to Elmo #4

Exceptions to the octet When we must exceed the octet, extra electrons go on central atom. (expanded octet) ClF 3 XeO 3 ICl 4 - BeCl 2

Consider XeF 4, 36 valence electrons. Octet structure uses 32 electrons. Put extra e - around Xe ELMO 5 In a few molecules, there are less than eight electrons around the central atom

Resonance Sometimes there is more than one valid structure for an molecule or ion. NO 3 - Transparency 6 True structure is a hybrid of those three forms Use double arrows to indicate it is the “average” of the structures. It doesn’t switch between them.

Note that….. Resonance forms are obtained by moving electrons, not atoms. Resonance can be expected when is possible to draw more that one structure that follows the octet rule

VSEPR Lewis structures tell us how the atoms are connected to each other. They don’t tell us anything about shape. The shape of a molecule can greatly affect its properties. Valence Shell Electron Pair Repulsion Theory allows us to predict geometry

VSEPR Molecules take a shape that puts electron pairs as far away from each other as possible. Have to draw the Lewis structure to determine electron pairs. bonding nonbonding lone pair Lone pair take more space. Multiple bonds count as one pair.

Linear

Octahedral