Ch. 7 presentation - part I Chapter 7: part I Resources: Class powerpoint presentation Textbook, chapter 7, sections Sections 7.3 and 7.1 Metal samples and conductivity sticks Chapter 7 reading and study guide Video - Sodium metal and chlorine gas POGIL: Chemical formulas and Names of Ionic Compounds Regents reference Tables E, S and the Regents periodic Table Prentice Hall review workbook – Unit 2 (in part) & unit 6 (in part)

End Show Slide 2 of 19 © Copyright Pearson Prentice Hall Bonding in Metals > Metallic Bonds and Metallic Properties What are some of the properties of metals? (review from chapter 6) __________________________________ __________________________________ __________________________________ __________________________________ 7.3

End Show © Copyright Pearson Prentice Hall Slide 3 of 19 Bonding in Metals > Sea of electrons model used to explain bonding between metal atoms; it is also useful in explaining characteristics of metals (they conduct electricity, are maleable, are ductile, etc.) The valence electrons of metal atoms can be modeled as a sea of electrons. The model involves a positively charged kernel (nucleus and nonvalence electrons) and valence electrons that are free to move or drift freely from one part of the metal to another. In this model the valence electrons are mobile. Metallic bonds consist of the attraction of the free-floating valence electrons for the positively charged kernel of the metal atom

End Show Slide 4 of 19 © Copyright Pearson Prentice Hall Bonding in Metals > Metallic Bonds and Metallic Properties Metals are ductile—that is, they can be drawn into wires. 7.3

End Show Slide 5 of 19 © Copyright Pearson Prentice Hall Bonding in Metals > Metallic Bonds and Metallic Properties A force can change the shape of a metal. A force can shatter an ionic crystal. 7.3

End Show © Copyright Pearson Prentice Hall Bonding in Metals > Slide 6 of 19 Crystalline Structure of Metals How are metal atoms arranged? Metal atoms are arranged in very compact and orderly patterns. 7.3

End Show Slide 7 of 19 © Copyright Pearson Prentice Hall Bonding in Metals > Alloys are mixtures composed of two or more elements, at least one of which is a metal. Alloys are important because their properties are often superior to those of their component elements. Alloys Bicycle frames are often made of titanium alloys that contain aluminum and vanadium. 7.3

End Show Slide 8 of 19 © Copyright Pearson Prentice Hall Bonding in Metals > Alloys The most important alloys today are steels. Steels have a wide range of useful properties, such as corrosion resistance, ductility, hardness, and toughness. 7.3

End Show © Copyright Pearson Prentice Hall Slide 9 of 19 Section Quiz -or- Continue to: Launch: Assess students’ understanding of the concepts in Section 7.3 Section Quiz. 7.3.

© Copyright Pearson Prentice Hall Slide 10 of 19 End Show 1.The valence electrons of metals can be modeled as a.a body-centered cube. b.octets of electrons. c.a rigid array of electrons. d.a sea of electrons. 7.3 Section Quiz.

© Copyright Pearson Prentice Hall Slide 11 of 19 End Show 2. In most metals, the atoms are a.free to move from one part of the metal to another. b.arranged in a compact and orderly pattern. c.placed at irregular locations. d.randomly distributed. 7.3 Section Quiz.

© Copyright Pearson Prentice Hall Slide 12 of 19 End Show 3. Alloys are important because they a.are pure substances. b.are the ores from which metals can be refined. c.can have properties superior to those of their components. d.are produced by the combustion of metals. 7.3 Section Quiz.

© Copyright Pearson Prentice Hall Slide 13 of 19 End Show Valence Electrons and Chemical Properties a.Valence electrons are the electrons in the highest occupied energy level of an element’s atoms. b.The number of valence electrons largely determines the chemical properties of an element. c.To find the number of valence electrons in an atom of a representative element, simply look at its group number and its electron configuration (ref. Periodic Table). 7.1

© Copyright Pearson Prentice Hall Slide 14 of 19 End Show The Octet Rule a.Noble gases, such as neon and argon, are unreactive in chemical reactions. In 1916, chemist Gilbert Lewis used this fact to explain why atoms form certain kinds of ions and molecules. b.He called his explanation the octet rule: In forming compounds, atoms tend to achieve the electron configuration of a noble gas. 7.1

© Copyright Pearson Prentice Hall Slide 15 of 19 End Show The Octet Rule Atoms of which elements tend to gain electrons? Atoms of which elements tend to lose electrons? 7.1

© Copyright Pearson Prentice Hall Slide 16 of 19 End Show The Octet Rule Atoms of metals tend to lose their valence electrons, leaving a complete octet in the next-lowest energy level. Atoms of some non- metals tend to gain electrons or to share electrons with another nonmetal to achieve a complete octet. 7.1

© Copyright Pearson Prentice Hall Slide 17 of 19 End Show Formation of Cations How are cations formed? An atom’s loss of valence electrons produces a cation, or a positively charged ion. 7.1

© Copyright Pearson Prentice Hall Slide 18 of 19 End Show Formation of Cations a.The most common cations are those produced by the loss of valence electrons from metal atoms. b.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. 7.1

© Copyright Pearson Prentice Hall Slide 19 of 19 End Show Formation of Cations a.The electron configuration of the sodium ion is the same as that of a neon atom. 7.1

© Copyright Pearson Prentice Hall Slide 20 of 19 End Show Formation of Cations a.Using electron dot structures, you can show the ionization more simply. 7.1

© Copyright Pearson Prentice Hall Slide 21 of 19 End Show Formation of Cations a.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

© Copyright Pearson Prentice Hall Slide 22 of 19 End Show Formation of Cations a.Cations of Group 1 (alkali metals, 1A) elements always have a charge of 1+. Cations of group 2 (alkaline earth metals, 2A) elements always have a charge of

© Copyright Pearson Prentice Hall Slide 23 of 19 End Show Formation of Anions How are anions formed? The gain of negatively charged electrons by a neutral atom produces an anion. a.An anion is an atom or a group of atoms with a negative charge. b.The name of an anion typically ends in -ide. 7.1

© Copyright Pearson Prentice Hall Slide 24 of 19 End Show Formation of Anions a.The figure shows the symbols of anions formed by some elements in Groups 15 (5A), 16 (6A), and 17 (7A). 7.1

© Copyright Pearson Prentice Hall Slide 25 of 19 End Show Formation of Anions a.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. 7.1

© Copyright Pearson Prentice Hall Slide 26 of 19 End Show Formation of Anions a.Both a chloride ion and the argon atom have an octet of electrons in their highest occupied energy levels. 7.1

© Copyright Pearson Prentice Hall Slide 27 of 19 End Show Formation of Anions a.In this equation, each dot in the electron dot structure represents an electron in the valence shell in the electron configuration diagram. 7.1

© Copyright Pearson Prentice Hall Slide 28 of 19 End Show Formation of Anions a.The negatively charged ions in seawater—the anions—are mostly chloride ions. 7.1

© Copyright Pearson Prentice Hall Slide 29 of 19 End Show Formation of Anions a.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. All halogen atoms need to gain only one electron to achieve the electron configuration of a noble gas. 7.1

© Copyright Pearson Prentice Hall Slide 30 of 19 End Show Formation of Anions a.Oxygen is in Group 16 (6A). 7.1

© Copyright Pearson Prentice Hall Slide 31 of 19 End Show Conceptual Problem

© Copyright Pearson Prentice Hall Slide 32 of 19 End Show Conceptual Problem

© Copyright Pearson Prentice Hall Slide 33 of 19 End Show Conceptual Problem

© Copyright Pearson Prentice Hall Slide 34 of 19 End Show for Conceptual Problem 7.1

© Copyright Pearson Prentice Hall Slide 35 of 19 End Show 7.1 Section Quiz. 7.1.

© Copyright Pearson Prentice Hall Slide 36 of 19 End Show 7.1 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 37 of 19 End Show 7.1 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 38 of 19 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. 7.1 Section Quiz.

END OF SHOW