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Chapter 7

Chapter 7. Ionic and Metallic Bonding. Section 1. Ions. Learning Targets. 7.1.1 – I can determine the number of valence electrons in an atom of a representative element. 7.1.2 – I can explain how the octet rule applies to atoms of metallic and nonmetallic elements.

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Chapter 7

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  1. Chapter 7 Ionic and Metallic Bonding

  2. Section 1 Ions

  3. Learning Targets 7.1.1 – I can determine the number of valence electrons in an atom of a representative element. 7.1.2 – I can explain how the octet rule applies to atoms of metallic and nonmetallic elements. 7.1.3 – I can describe how cations form. 7.1.4 – I can explain how anions form.

  4. Valence Electrons • Valence electrons – electrons in the highest occupied energy level of an elements atoms. • Valence electrons determine an elements properties.

  5. To find the number of valence electrons simply look at the group number. • Helium is the only exception to this, only has 2 electrons. • Electron dot structure – diagrams that show the valence electrons as dots.

  6. The Octet Rule • Octet rule – in forming compounds, atoms tend to achieve the electron configuration of noble gases. • Or the configuration of ns2np6

  7. Atoms of metallic elements tend to lose their valence electrons, leaving a complete octet in the next-lowest energy level. • Atoms of nonmetallic elements tend to gain electrons or share electrons with another nonmetallic element to achieve a complete octet.

  8. Formation Of Cations • An atom’s loss of valence electrons produces a cation, or a positively charged ion. • Usually metal atoms – very few nonmetals lose electrons.

  9. Transition metals will achieve the most stable configuration possible so they may be exceptions to the octet rule. • Also called a pseudo-noble gas electron configuration.

  10. Which looks like

  11. Formation Of Anions • The gain of negatively charged electrons by a neutral atom produces an anion. • Nonmetals form anions and change their name endings to –ide. • Halide ion – ions produced when atoms of chlorine and the other halogens gain electrons.

  12. Which looks like

  13. Section 2 Ionic Bonds and Ionic Compounds

  14. Learning Targets 7.2.1 – I can explain the electrical charge of an ionic compound. 7.2.2 – I can describe three properties of ionic compounds.

  15. Formation of Ionic Compounds • Ionic compound – compounds composed of cations and anions. • Although they are composed of ions, ionic compounds are electrically neutral. • Sodium reacting with chlorine 1 • Sodium reacting with chlorine 2 • Aluminum reacting with bromine • Sodium reacting with bromine • Aluminum reacting with iodine

  16. Ionic Bonds • Ionic bonds – electrostatic forces that hold ions together in ionic compounds. • Think about sodium and chloride • Sodium has 1 valence electron. • Chlorine has 7 valence electron. • When they combine sodium gives chlorine its 1 valence electron so they both satisfy the octet rule.

  17. Formula Units • Chemical formulas – shows the kinds and numbers of atoms in the smallest representative unit of a substance. • Formula unit – lowest whole-number ratio of ions in an ionic compound.

  18. Examples: • Look at sodium and oxygen

  19. Examples: • Look at aluminum and oxygen

  20. Examples: • Pick a metal from the representative elements. • Pick a nonmetal from the representative elements

  21. Properties OF Ionic Compounds • Most ionic compounds are crystalline solids at room temperature. • Ionic compounds generally have high melting points.

  22. Coordination number – number of ions of opposite charge that surround the ion in a crystal

  23. Ionic compounds can conduct an electric current when melted or dissolved in water.

  24. Section 3 Bonding In Metals

  25. Learning Targets 7.3.1 – I can model the valence electrons of metal atoms. 7.3.2 – I can describe the arrangement of atoms in a metal. 7.3.3 – I can explain the importance of alloys.

  26. Metallic Bonds and Metallic Properties • The valence electrons of metal atoms can be modeled as a “sea” of electrons. • Metallic bonds – attraction of the free-floating valence electrons for the positively charged metal atoms.

  27. Metallic Bonds and Metallic Properties • Good conductors of electrical current because of the free-floating electrons. • Malleable (pounded into sheets) • Ductile (pulled into wires)

  28. Crystalline Structure of Metals • Metal atoms are arranged in very compact and orderly patterns.

  29. Alloys • Alloy – 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 the component elements.

  30. Substitutional alloy – components are about the same size and one replaces (substitutes) another. • Interstitial alloy – components are different sizes and smaller fits into the spaces (intercies) of the larger.

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