LECTURE 6: COVALENT COMPOUNDS

Binary Covalent Molecules Contains 2 atoms covalently bonded together What is a covalent bond? 2 Nonmetals bonded together Rules: Do the same as before Add prefixes

Binary Covalent Molecules

Naming Covalent Compounds, continued Section 2 Drawing and Naming Molecules Chapter 6 Naming Covalent Compounds, continued Prefixes can be used to show the numbers of each type of atom in diphosphorus pentasulfide.

Sample Problems Name the following covalent compounds CO CO2 NO2 N2O4

Sample Problems Name the following covalent compounds CO – carbon monoxide CO2 – carbon dioxide NO2 – nitrogen dioxide N2O4 – dinitrogen tetraoxide

Writing Binary Formula Example: Carbon Monoxide Carbon = C Monoxide (1 oxide) = O Formula: CO

Naming Compounds Using Numerical Prefixes Chapter 6 Visual Concepts Naming Compounds Using Numerical Prefixes

CHEMICAL BONDS

Chapter 6 Visual Concepts Chemical Bond

Chemical Bond A mutual attraction between nuclei and valence electrons of different atoms Only includes “s” and “p” orbitals This leads us to the ……

Types of Bonds Ionic Bonding – e- are transferred Covalent Bonding – e- are shared Metallic Bonding – e- are mobile around a large cluster of nuclei

Types of Bonds Cation the + charged ion that loses the e- Anion the – charged ion that gains the e- Orbitals overlap to create a sharing of e- e- move freely around the nuclei Movement creates electricity, malleability, ductility

Ionic Bonds Occurs between a metal and a nonmetal Electronegativity values have a difference >2.1 Metal becomes a cation (+) by giving up 1 or more e- Nonmetal becomes an anion (-) by taking 1 or more e-

Covalent Bonds Occurs between a nonmetal and a nonmetal Electronegativity values have a difference of < 2.1 Electrons are shared by both atoms

Predicting Bond Character from Electronegativity Differences Chapter 6 Predicting Bond Character from Electronegativity Differences

Comparing Polar and Nonpolar Covalent Bonds Chapter 6 Visual Concepts Comparing Polar and Nonpolar Covalent Bonds

Metallic Bonding Occurs between 2 or more metal atoms Electrons float around freely creating a negative “sea of electrons” and a positively charged nuclei center

Hydrogen Bonding Special Case Occurs between hydrogen and another element Typically N, O, or any of the halogens

Properties of Substances with Metallic, Ionic, and Covalent Bonds

Octet Rule “Eight is great” Every atom wants a total of 8 valence electrons 2 in the s orbital 6 in the p orbital

Drawing Chemical Bonds LEWIS DOT STRUCTURES Drawing Chemical Bonds

Drawing Lewis Dot Structures Group 1 Write the element symbol Draw a dot for every valence electron Dots should be in the form of a box Group 1 Ends in s1 1 valence electron 1 dot

Lewis Electron-Dot Structures, continued Section 2 Drawing and Naming Molecules Chapter 6 Lewis Electron-Dot Structures, continued Lewis Structures Show Valence Electrons As you go from element to element across a period, you add a dot to each side of the element’s symbol.

Lewis Dot Structures Group 2 Group 13 Ends in s2 2 valence electrons Ends in s2 p1 3 valence electrons 3 dots

Lewis Electron-Dot Structures, continued Section 2 Drawing and Naming Molecules Chapter 6 Lewis Electron-Dot Structures, continued Lewis Structures Show Valence Electrons, continued You do not begin to pair dots until all four sides of the element’s symbol have a dot.

Lewis Dot Structures Group 14 – 18 You get the idea 4-8 valence electrons 4-8 dots

Lewis Dot Structures for Compounds Rule 1: Write the symbol for the element Rule 2: Use the group # to determine the # of valence electrons Rule 3: Draw the correct # of dots (box) around the symbol

Example

Sample Problems Draw the Lewis Dot Structure for: Carbon Tetrachloride CCl4. Water, H2O. Carbon Dioxide, CO2. Nitrogen, N2

Comparing Single, Double, and Triple Bonds Chapter 6 Comparing Single, Double, and Triple Bonds

Multiple Bonds For O2 to make an octet, each atom needs two more electrons. The two atoms share four electrons. A double bond is a covalent bond in which two atoms share two pairs of electrons.

Multiple Bonds, continued For N2 to make an octet, each atom needs three more electrons. The two atoms share six electrons. A triple bond is a covalent bond in which two atoms share three pairs of electrons.

Chapter 6 Standardized Test Preparation 1. Which of these combinations is likely to have a polar covalent bond? A. two atoms of similar size B. two atoms of very different size C. two atoms with different electronegativities D. two atoms with the same number of electrons

Understanding Concepts Chapter 6 Standardized Test Preparation Understanding Concepts 1. Which of these combinations is likely to have a polar covalent bond? A. two atoms of similar size B. two atoms of very different size C. two atoms with different electronegativities D. two atoms with the same number of electrons

3. How many electrons are shared in a double covalent bond? Chapter 6 Standardized Test Preparation Understanding Concepts 3. How many electrons are shared in a double covalent bond? A. 2 B. 4 C. 6 D. 8

3. How many electrons are shared in a double covalent bond? Chapter 6 Standardized Test Preparation Understanding Concepts 3. How many electrons are shared in a double covalent bond? A. 2 B. 4 C. 6 D. 8