Chapter 7 Ionic and Metallic Bonding

1. Chapter 7Ionic and Metallic Bonding Mr. Samaniego Lawndale High School

2. Section 7.1 - Ions • When Mendeleev arranged his periodic table according to properties, he didn’t know that it was also due to the number of bonding electrons • The reason that certain elements were grouped together was because they have the same number of valence electrons • Valence Electrons – electrons in the highest occupied energy level of an atom • To find the valence electrons in an atom of the representative element, simply look at the group number

3. He 2 e-

4. Determine the Valence electrons in each of these elements • K 6. Be • P 7. Li • C 8. He • O 9. Ne • N 10. B

5. Electron Dot Structure • A diagram that shows valence electrons as dots around the element symbol PRACTICE 1. K 6. Be 2. P 7. Li 3. C 8. He 4. O 9. Ne 5. N 10. B

6. Valence Electrons • The reason that valence electrons are so important is that they are the only electrons involved in bonding

7. Octet Rule • Remember that all atoms want to be like the noble gases because their s and p orbitals are completely filled, which makes them unreactive and stable • The Octet Rule states that all atoms want 8 electrons in their valence shells, just like the noble gases (except He)

8. Satisfying the Octet Rule • In forming compounds, atoms want to achieve a noble gas configuration • In order for atoms to combine together to obtain 8 valence electrons, they transfer electrons (either gain or lose electrons)

9. Some atoms will gain electrons, while other atoms will lose electrons Filling Order: 1s 2s 2p 3s 3p 4s 3d 4p • Draw the orbital diagram for Sodium • Draw the orbital diagram for Magnesium • Draw the orbital diagram for Fluorine • Draw the orbital diagram for Oxygen

10. Cation versus Anion • Remember that atoms are electrically neutral because they have the same number of protons and electrons

11. How are electrons transferred? • Metals lose valence electrons • Nonmetals gain valence electrons

12. Bonding • Once an atom has a stable octet, it is happy and does not want to react anymore • Atoms without stable octets are sad and want to react with other atoms to achieve a stable octet • Why don’t noble gases want to form bonds?

13. Why do atoms form bonds?1. To have a full octet2. To be more stable3. To be less reactive How do atoms become more stable and less reactive? By having completely filled s and p orbitals just like the noble gases

14. Charges on the Periodic Table

15. Practice • What are the charges on the following elements? • Calcium • Oxygen • Chlorine • Hydrogen • Cesium • Helium • Krypton • Aluminum

16. Section 7.2 – Ionic Bonds • Ionic Compounds are METAL cations and NONMETAL anions held together by electrostatic forces • Ionic compounds are formed through transferring or exchanging electrons

17. Example… • Sodium Chloride (Salt, NaCl) is an example of an ionic compound

18. Practice • Which of the following are ionic compounds? • LiCl • NaS • C2H4 • MgBr2 • H2O • SiC • Rb3P • CsI

19. Ionic Charges • Although they are composed of positive and negative charges, ionic compounds are overall electrically neutral because their charges will cancel out • For example… • Na+1 will bond with Cl-1 • Mg2+ will bond with O2- • Al3+ will bond with N3- • Two K+1 can also bond with One S2-

20. Writing Chemical Formulas S2- S2- Al3+ S2- Al3+ Al2S3 The numbers on top are the charges, while the numbers on the bottom tell how many atoms there are

21. Practice Write as many compounds as you can with the following ions. Remember that the overall charge must be zero. There are 9 possible.

22. Salt • Salt crystals are repeating patterns of positive and negative ions held together by electrostatic attraction

23. Ionic Bonding • When cations and anions transfer electrons, a SALT is formed • Draw the electron dot structure for the following atoms • Li and Br • Mg and O • Two K and One S • One Sr and Two F

24. SALTS When cations and anions form bonds with each other they are called SALTS • Example: Li 1s 2p F 1s 2p Li+ LiF F-

25. Practice Show how the following compounds bond with the use of orbital diagrams • NaF • MgO • Li2S • CaCl2 • AlN

26. Properties of Ionic Compounds • CrystallineSolid at Room Temperature • High Melting Points • Can conduct an electric current when melted or dissolved in water

27. Section 7.3 – Bonding in Metals • Metal atoms are arranged in very compact and orderly patterns

28. Metallic Bond • A Metallic Bond is a bond between metal cations surrounded by a sea of electrons

29. Metallic Bond The attraction of the free floating valence electrons holds them together

30. Crystalline Structure of Metals(Page 202)

31. Properties of Metals Good Conductors of electrical current 2. Ductile (ability to be stretched) 3. Malleable (ability to be shaped)

32. Alloys • Very few of the metal objects you use everyday are pure metals • Alloys are a mixture of two or more elements, at least one being a metal • Alloys are important because the combination of metals are stronger than the single metal by itself

33. Examples of Alloy Combinations • Brass – copper and zinc • Sterling Silver – silver and copper • Bronze – copper and tin • Steel – iron, carbon, boron, chromium, manganese, molybdenum, nickel, tungsten, vanadium • Stainless Steel – iron, chromium, carbon, nickel • Cast Iron – iron and carbon

34. Homework Chapter 7 Assessment #’s 30-44, 48, 53, 55, 56, 58, 59, 60, 62, 63, 64, 65, 72, 73, 87, 88, 90, 92, 93, 94, 95