Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Table of Contents Chapter 6 Chemical Bonding Section 1 Introduction to Chemical Bonding Section 2 Covalent Bonding and Molecular Compounds Section 3 Ionic Bonding and Ionic Compounds Section 4 Metallic Bonding Section 5 Molecular Geometry

End Show © Copyright Pearson Prentice Hall 2 Slide of 39 Ions Pyrite (FeS 2 ), a common mineral that emits sparks when struck against steel, is often mistaken for gold— hence its nickname, “fool’s gold.” Pyrite is an example of a crystalline solid. In this chapter, you will learn about crystalline solids composed of ions that are bonded together. But first you need to understand how ions form from neutral atoms. 6.1A

End Show © Copyright Pearson Prentice Hall 3 Ions > Slide of 39 Valence Electrons How do you find the number of valence electrons in an atom of a representative element? 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 4 Ions > Valence Electrons Valence electrons are the electrons in the highest occupied energy level of an element’s atoms. The number of valence electrons largely determines the chemical properties of an element. 6.1A

End Show © Copyright Pearson Prentice Hall 5 Slide of 39 Ions > Valence Electrons To find the number of valence electrons in an atom of a s-block element, simply look at its group number. Example Na would have 1 valence electron and Ca would have 2. For p-block elements, the number of valence electrons is the Group number less 10 with the method of our periodic table, so B would have 3 valence electrons and Fluorine has 7 (2 from s orbital and 5 from p orbitals) 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 6 Ions > Valence Electrons Applications of Group 14 Elements (also sometimes called Group 4A with some periodic tables.) 6.1A Carbon Silicon Germanium Text

7 End Show Slide of 39 © Copyright Pearson Prentice Hall Ions > From section 5.3 An ion is an atom or group of atoms that has a positive or negative charge and was created from a transfer of 1 or more electrons A

End Show © Copyright Pearson Prentice Hall 8 Ions > Slide of 39 Formation of Cations How are cations formed? 6.1A

End Show © Copyright Pearson Prentice Hall 9 Slide of 39 Ions > Formation of Cations An atom’s loss of valence electrons produces a cation, or a positively charged ion. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 10 Ions > Formation of Cations The most common cations are those produced by the loss of valence electrons from metal atoms. You can represent the electron loss, or ionization, of the sodium atom by drawing the complete electron configuration of the atom and of the ion formed. 6.1A

End Show © Copyright Pearson Prentice Hall 11 Slide of 39 Ions > Formation of Cations The electron configuration of the sodium ion is the same as that of a neon atom. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 12 Ions > Formation of Cations Using electron dot structures, you can show the ionization more simply. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 13 Ions > Formation of Cations The sodium atoms in a sodium-vapor lamp ionize to form sodium cations. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 14 Ions > Formation of Cations A magnesium atom attains the electron configuration of neon by losing both valence electrons. The loss of valence electrons produces a magnesium cation with a charge of A

End Show Slide of 39 © Copyright Pearson Prentice Hall 15 Ions > Formation of Cations Walnuts are a good dietary source of magnesium. Magnesium ions (Mg 2+ ) aid in digestive processes. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 16 Ions > Formation of Cations Cations of Group 1 (or 1A) elements always have a charge of 1+. Cations of group 2 (or 2A) elements always have a charge of A

End Show © Copyright Pearson Prentice Hall 17 Slide of 39 Ions > Formation of Cations A copper atom can ionize to form a 1+ cation (Cu + ). By losing its lone 4s electron, copper attains a pseudo noble-gas electron configuration. 6.1A

End Show © Copyright Pearson Prentice Hall 18 Ions > Slide of 39 Formation of Anions How are anions formed? 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 19 Ions > Formation of Anions The gain of negatively charged electrons by a neutral atom produces an anion. An anion is an atom or a group of atoms with a negative charge. The name of an anion typically ends in -ide. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 20 Ions > Formation of Anions The figure shows the symbols of anions formed by some elements in Groups 15 (or 5A), 16 (or 6A), and 17 (or 7A). 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 21 Ions > Formation of Anions A gain of one electron gives chlorine an octet and converts a chlorine atom into a chloride ion. It has the same electron configuration as the noble gas argon. 6.1A

End Show © Copyright Pearson Prentice Hall 22 Slide of 39 Ions > Formation of Anions Both a chloride ion and the argon atom have an octet of electrons in their highest occupied energy levels. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 23 Ions > Formation of Anions In this equation, each dot in the electron dot structure represents an electron in the valence shell in the electron configuration diagram. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 24 Ions > Formation of Anions The negatively charged ions in seawater—the anions—are mostly chloride ions. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 25 Ions > Formation of Anions The ions that are produced when atoms of chlorine and other halogens gain electrons are called halide ions. All halogen atoms have seven valence electrons. They are a nonmetal. All halogen atoms need to gain only one electron to achieve the electron configuration of a noble gas. Halide ions often combine with metal cation. Metals and nonmetals often combine to form a group of compounds called “salts”. 6.1A

End Show © Copyright Pearson Prentice Hall 26 Slide of 39 Ions > Formation of Anions Oxygen is in Group 6A. 6.1A

End Show Slide of 39 © Copyright Pearson Prentice Hall 27 Ions > Formation of Anions 6.1A Common elemental anions and polyatomic anions

© Copyright Pearson Prentice Hall Slide of 39 End Show Conceptual Problem A

© Copyright Pearson Prentice Hall Slide of 39 End Show Conceptual Problem

© Copyright Pearson Prentice Hall Slide of 39 End Show Conceptual Problem A

End Show © Copyright Pearson Prentice Hall Slide of 27 Section Quiz -or- Continue to: Launch: Assess students’ understanding of the concepts in Section 6.1A Section Quiz. 6.1A.

© Copyright Pearson Prentice Hall Slide of 39 End Show 6.1A Section Quiz. 1. How many valence electrons are there in an atom of oxygen? a.2 b.4 c.6 d.8

© Copyright Pearson Prentice Hall Slide of 39 End Show 6.1A Section Quiz. 2. Atoms that tend to gain a noble gas configuration by losing valence electrons are a.metals. b.nonmetals. c.noble gases. d.representative elements.

© Copyright Pearson Prentice Hall Slide of 39 End Show 3. When a magnesium atom forms a cation, it does so by a.losing two electrons. b.gaining two electrons. c.losing one electron. d.gaining one electron. 6.1A Section Quiz.

© Copyright Pearson Prentice Hall Slide of 39 End Show 4. When a bromine atom forms an anion, it does so by a.losing two electrons. b.gaining two electrons. c.losing one electron. d.gaining one electron 6.1A Section Quiz.

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Define chemical bond. Explain why most atoms form chemical bonds. Describe ionic and covalent bonding. Explain why most chemical bonding is neither purely ionic nor purely covalent. Classify bonding type according to electronegativity differences. Section 1B Introduction to Chemical Bonding Chapter 6

End Show © Copyright Pearson Prentice Hall 37 Slide of 18 Molecular Compounds These toy models are made from circular pieces joined together in units by sticks. Atoms can also be arranged in different ways to make a variety of products. 6.1B

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Chemical Bond Chapter 6 udent/ch06/sec01/vc00/hc606_01_v00fs. htm

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonds A chemical bond is a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together. Nature favors arrangements in which potential energy is minimized. By bonding with each other, atoms decrease in potential energy, creating more stable arrangements of matter. Types of chemical bonding that results from the electrical attraction between cations and anions is ionic bonding. These bonds resulted from a metal and nonmetal due to transfer of electrons. 6.1B

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Ionic Bonding Ch dent/ch06/sec01/vc01/hc606_01_v01fs.ht m

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Covalent Bonds Covalent bonding results from the sharing of electron pairs between two atoms. These are usually made up of 2 nonmetals. 6.1B

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Covalent Bonding 6.1 B x/student/ch06/sec01/vc02/hc606_01_ v02fs.htm

End Show © Copyright Pearson Prentice Hall 43 Slide of 28 Polar Bonds and Molecules Snow covers approximately 23 percent of Earth’s surface. Each individual snowflake is formed from as many as 100 snow crystals. The polar bonds in water molecules influence the distinctive geometry of snowflakes. 6.1

End Show © Copyright Pearson Prentice Hall 44 Polar Bonds and Molecules > Slide of Bond Polarity How do differences in electronegativity values help determine the type of bond formed?

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of chemical bonds and electronegativity The degree to which bonding between atoms of two elements is ionic or covalent can be estimated by calculating the difference in the element’s electronegativity. 6.1B

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Electronegativity differences determining bonds a) An electronegativity difference > 1.7 is an ionic bond. Example: Cs and S see pg. 161 chart? Cs 2.5 and S 0.7 Find the difference of electronegativity values = 1.8 so Cs + and S - should form an ionic bond and thus an ionic compound. The electron will transfer from the metal Cs to the nonmetal S. 6.1B

End Show © Copyright Pearson Prentice Hall 47 Polar Bonds and Molecules > Slide of Bond Polarity How do electronegativity values determine the charge distribution in a polar bond?

End Show Slide of 33 © Copyright Pearson Prentice Hall 48 Polar Bonds and Molecules > 6.1 Bond Polarity The bonding pairs of electrons in covalent bonds are pulled by the nuclei.

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Electronegativity differences determining bonds b) An electronegativity difference difference of 0.3 to 1.7 is polar. Bonds that have an uneven distribution of charge are polar. A polar-covalent bond is a covalent bond in which the bonded atoms have an unequal attraction for the shared electron. Example A1): H 2 S 6.1B

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding, continued Sample Problem A1 Use electronegativity values listed in Figure 20 from the previous chapter in your book, on page 161, and Figure 2 in your book, on page 176, to classify bonding between sulfur, S, and the following elements: hydrogen, H. In the pair, which atom will be more negative? Section 1 Introduction to Chemical Bonding ch. 6.1

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem A1 Solution The electronegativity of sulfur is 2.5. The electronegativity of hydrogen is 2.1. The atom with the larger electronegativity will be the more-negative atom. Section 1 Introduction to Chemical Bonding 6.1B Bonding betweenElectroneg.More-neg- sulfur anddifferenceBond typeative atom hydrogen2.5 – 2.1 = 0.4polar-covalentsulfur Chemical Bonding, continued Since S has a greater electronegativity value, electrons are closer to S causing partial charges.

End Show Slide of 33 © Copyright Pearson Prentice Hall 52 Polar Bonds and Molecules > 6.1 Bond Polarity A polar covalent bond, known also as a polar bond, is a covalent bond between atoms in which the electrons are shared unequally. The more electronegative atom attracts electrons more strongly and gains a slightly negative charge. The less electronegative atom has a slightly positive charge.

End Show Slide of 33 © Copyright Pearson Prentice Hall 53 Polar Bonds and Molecules > 6.1 Bond Polarity Example with H and Cl which is polar covalent. The chlorine atom attracts the electron cloud more than the hydrogen atom does.

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Electronegativity differences determining bonds Need to draw picture of H 2 S with partial charges shown. 6.1B

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Covalent Bonds c) A covalent bond where electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge, is a nonpolar covalent bond. Electronegativity differences of 0 to 0.3 are non-polar covalent bonds. (Some references use 0 to 0.4 as non- polar covalent bonds and 0.4 to 2 for polar covalent.) Example: Cl = 0 difference so this is non-polar and electrons are shared equally. 6.1B

End Show Slide of 33 © Copyright Pearson Prentice Hall 56 Polar Bonds and Molecules > 6.1 Bond Polarity When the atoms in a covalent bond pull equally (as occurs when identical atoms are bonded), the bonding electrons are shared equally, and the bond is a nonpolar covalent bond. Examples H 2, Cl 2

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Using Electronegativity Difference to Classify Bonding Chapter 6 x/student/ch06/sec01/vc04/hc606_01_ v04fs.htm Please watch to help clarify classifications of bonds based upon electronegativity differences.

End Show Slide of 33 © Copyright Pearson Prentice Hall 58 Polar Bonds and Molecules > Bond Polarity 6.1 Other curriculum uses this table Holt pg. 176

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Comparing Polar and Nonpolar Covalent Bonds Chapter 6 In covalent bonds, atoms share electron pairs. If they share them equally, the covalent bond is nonpolar. If the electrons are more strongly attracted to one of the atoms, the covalent bond is polar.

60 End Show Slide of 33 © Copyright Pearson Prentice Hall Polar Bonds and Molecules > Complete the Practice problems on page 177 and place in your notes. 60 DO THIS BEFORE GOING TO NEXT SLIDE.

61 End Show Slide of 33 © Copyright Pearson Prentice Hall Polar Bonds and Molecules > Complete the Practice problems on page 177 and place in your notes. 61

© Copyright Pearson Prentice Hall Slide of 33 End Show 6.1B Section Quiz. 1.In a molecule, the atom with the largest electronegativity value a.repels electrons more strongly and acquires a slightly negative charge. b.repels electrons more strongly and acquires a slightly positive charge. c.attracts electrons more strongly and acquires a slightly positive charge. d.attracts electrons more strongly and acquires a slightly negative charge.

© Copyright Pearson Prentice Hall Slide of 25 End Show Online Self-Check Quiz 6.1 Complete the online Quiz and record answers. Ask if you have any questions about your answers. click here for online Quiz 6.1 (8 questions) You must be in the “Play mode” for the slideshow for hyperlink to work.

© Copyright Pearson Prentice Hall Slide of 28 End Show VIDEOS FOR ADDITIONAL INSTRUCTION Additional Videos for Section 6.1: Introduction to Chemical Bonding Ionic Bond (5:11)Ionic Bond Covalent Bonds (2:35)Covalent Bonds Polarity (5:12)Polarity

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu End of Section 6.1 Show