1 / 112

Chapter 4 Compounds and Their Bonds

Chapter 4 Compounds and Their Bonds. 4.1 Valence Electrons 4.2 Octet Rule and Ions. Valence Electrons. The valence electrons are the electrons in the outer shell.

emma
Télécharger la présentation

Chapter 4 Compounds and Their Bonds

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 4 Compounds and Their Bonds 4.1 Valence Electrons 4.2 Octet Rule and Ions

  2. Valence Electrons • The valence electronsare the electrons in the outer shell. • The electrons in the outer shell have the most contact with other atoms and strongly influence the chemical properties of atoms.

  3. Number of Valence Electrons • For Group A elements, the number of valence electrons is the number of electrons in the s and p subshells of the outer shell. • In the electron configuration for phosphorus, there are 5 valence electrons in the s and p subshells with the highest number. 5 valence electronsP Group 5A 1s22s22p63s23p3

  4. Valence Electrons for Groups

  5. Learning Check State the number of valence electrons for each. A. Magnesium 1) 2 2) 6 3) 8 B. Oxygen 1) 2 2) 4 3) 6 C. Potassium 1) 1 2) 2 3) 7

  6. Solution State the number of valence electrons for each. A. Magnesium 1) 2 Group 2A 1s22s22p63s2 B. Oxygen 3) 6 Group 6A 1s22s2 2p4 C. Potassium 1) 1 Group 1A 1s22s22p63s23p64s1

  7. Electron Dot Structure • An electron-dot structure is a convenient way to represent the valence electrons. • For example, the two valence electrons for magnesium are placed as single dots on any two sides of the Mg symbol.

  8. Electron-Dot Structures • Dot structures are used for Group A elements. • The valence electrons are placed on the sides of the symbol of an element.

  9. Learning Check  A. X is the electron dot formula for 1) Na 2) K 3) Al   B.  X  is the electron dot formula of  1) B 2) N 3) P

  10. Solution  A. X is the electron dot formula for 1) Na 2) K   B.Xis the electron dot formula of  2) N 3) P

  11. Octet Rule • The stability of the noble gases is associated with 8 valence electrons(He has 2). Ne 2,8Ar 2, 8,8Kr 2, 8, 18, 8 • Atoms can become more stable by acquiring an octet (8 electrons) in the outer shell. • The process of acquiring an octet involves the loss, gain, or sharingof valence electrons.

  12. Ionization Energy • Ionization energy is the energy it takes to remove a valence electron. • Metals have lower ionization energies and nonmetals have higher ionization energies.

  13. Metals Form Positive Ions • Metals acquire octets by losingvalenceelectrons. • The loss of electrons converts an atom to an ion that has the electron configuration of the nearest noble gas. • Metals form positiveionsbecause they have fewer electrons than protons. Group 1A metals ion 1+Group 2A metals ion 2+Group 3A metals ion 3+

  14. Learning Check Give the ionic charge for each ion. A. 12 p+ and 10 e- 1) 0 2) 2+ 3) 2- B. 50p+ and 46 e- 1) 2+ 2) 4+ 3) 4- C. 15 p+ and 18e- 2) 3+ 2) 3- 3) 5-

  15. Solution Give the ionic charge for each ion. A. 12 p+ and 10 e- 2) 2+ B. 50p+ and 46 e- 2) 4+ C. 15 p+ and 18e- 2) 3-

  16. Formation of a Sodium Ion, Na+ • Sodium forms an octet by losing its one valence electron. Na  – e Na + 1s22s22p63s11s22s22p6(= Ne) • A positive ion forms with a +1 charge. Sodium atomSodium ion 11 p+ 11 p+ 11 e-10 e- 01 +

  17. Formation of Mg2+ Magnesium forms an octet by losing its two valence electrons. Magnesium atomMagnesium ion  Mg  – 2e Mg2+ 1s22s22p63s21s22s22p6(= Ne) • A positive ion forms with a +2 charge. 12 p+ 12 p+ 12 e- 10 e- 02 +

  18. Formation of Negative Ions • When nonmetals gain electrons to achieve an octet arrangement, they form negative ions. • The ionic charge of a nonmetal is 3-, 2-, or 1-.

  19. Formation of a Fluoride Ion, F- • Fluorine forms an octet by adding an electron to its seven valence electrons.   1- : F  + e:F :  1s22s22p51s22s22p6(= Ne) • A negative ion forms with a -1 charge. Fluorine atom Fluoride ion 9 p+ 9 p+ 9 e-10 e- 01 –

  20. Group Number and Ions • The Group number can be used to determine the charge of an ion. • The charge of a positive ion is equal to its Group number. Group 3A = 3+ • The charge of a negative ion is obtained by subtracting its Group number from 8. Group 6A = - (8-6) = 2-

  21. Examples of Ionic Charges

  22. Some Important Ions in the Body

  23. Learning Check A. How many valence electrons does aluminum have? 1) 2e- 2) 3e- 3) 5e- B. How does aluminum acquire an octet? 1) loses 3e- 2) gains 3e- 3) gains 5e- C. What is the ionic charge of an aluminum ion? 1) 3- 2) 5- 3) 3+ D. The symbol for the aluminum ion is 1) Al3+ 2) Al3- 3) Al+

  24. Solution A. How many valence electrons does aluminum have? 2) 3e- B. How does aluminum acquire an octet? 1) loses 3e- C. What is the ionic charge of an aluminum ion? 3) 3+ D. The symbol for the aluminum ion is 1) Al3+

  25. Chapter 4 Compounds and Their Bonds 4.3 Ionic Compounds 4.4 Naming and Writing Ionic Formulas

  26. Ionic Compounds • Ionic compounds consist of positive and negative ions. • An ionic bond is an attraction between the positive and negative charges. • In an ionic formula, the total charge of the positive ions is equal to the total charge of the negative ions. total positive charge = total negative charge

  27. Ionic Formulas • The formulas of ionic compounds are determined from the charges on the ions. atoms ions  – Na +  F : Na+ : F : NaF  sodium fluorine sodium fluoride • The overall charge of NaF is zero (0). (1+ ) + (1-) = 0

  28. Charge Balance In NaCl • The formula does not show the charges of the ions in the compound. • The symbol of the metal is written first, followed by the symbol of the nonmetal.

  29. Charge Balance In MgCl2

  30. Writing a Formula from Charges Write the formula of the ionic compound that forms from Ba2+ and Cl. • Write the symbols of the positive ion and the negative ion. Ba2+ Cl • Balance the charges until the positive charge is equal to the negative charge. Ba2+ CltwoCl-neededCl • Write the formula using subscripts for the number of ions for charge balance. BaCl2

  31. Learning Check Write the correct formula for the ionic compound of A. Na+ and S2- 1) NaS 2) Na2S 3) NaS2 B. Al3+ and Cl- 1) AlCl3 2) AlCl 3) Al3Cl C. Mg2+ and N3- 1) MgN 2) Mg2N3 3) Mg3N2

  32. Solution A. Na+ and S2- 2) Na2S B. Al3+ and Cl- 1) AlCl3 C. Mg2+ and N3- 3) Mg3N2

  33. Names of Ions • Positive ions are named like the element. • Negative ions are named by changing the end of the element name to –ide.

  34. Learning Check Complete the names of the following ions: N3 O2 F _________ __________ _________ P3 S2 Cl _________ __________ _________ Br  _________

  35. Solution N3 O2 F nitrideoxidefluoride P3 S2 Cl phosphidesulfidechloride Br  bromide

  36. Naming Ionic Compounds with Two Elements • The name of a binary ionic compound (two elements) gives the name of the metal ion first and the name of the negative ion second. Examples: NaCl sodium chloride K2S potassium sulfide CaI2 calcium iodide Al2O3 aluminum oxide

  37. Learning Check Write the names of the following compounds: 1) Na3N ___________ 2) KBr ___________ 3) Al2S3 ___________ 4) MgO ___________

  38. Solution Complete the names of the following compounds: 1) Na3N sodium nitride 2) KBr potassium bromide 3) Al2S3aluminumsulfide 4) MgO magnesium oxide

  39. Ionic Charges of Transition Metals • Most transition elements have two or more positive ions.

  40. Summary of Common Ions • Of the transition metals, silver and zinc are important elements that form only one ion.

  41. Learning Check A. The formula for the ionic compound of Na+ and O2- is 1) NaO 2) Na2O 3) NaO2 B. The formula of a compound of aluminum and chlorine is 1) Al3Cl 2) AlCl2 3) AlCl3 C. The formula of Fe3+ and O2- is 1) Fe3O2 2) FeO3 3) Fe2O3

  42. Solution A. The formula for the ionic compound of Na+ and O2- is 2) Na2O B. The formula of a compound of aluminum and chlorine is 3) AlCl3 C. The formula of Fe3+ and O2- is 3) Fe2O3

  43. Naming Compounds with Transition Metals • Transition metals with two different ions use a Roman numeral following the name of the metal to indicate ionic charge.

  44. Learning Check Select the correct name for each. A. Fe2S3 1) iron sulfide 2) iron(II) sulfide 3) iron (III) sulfide B. CuSO4 1) copper sulfate 2) copper(I) sulfate 3) copper (II) sulfate

  45. Solution Select the correct name for each. A. Fe2S3 3) iron (III) sulfide B. CuSO4 3) copper (II) sulfate

  46. Learning Check The correct formula is A. Copper (I) nitride 1) CuN 2) CuN3 3) Cu3N B. Lead (IV) oxide 1) PbO2 2) PbO 3) Pb2O4

  47. Solution The correct formula is A. Copper (I) nitride 3) Cu3N B. Lead (IV) oxide 1) PbO2

  48. Chapter 4 Compounds and Their Bonds 4.5 Covalent Bonds 4.6 Naming and Writing Formulas of Covalent Compounds 4.7 Bond Polarity

  49. Covalent Bonds • Covalent bonds form between two nonmetals from Groups 4A, 5A, 6A, and 7A. • In a covalent bond, electrons are shared to complete octets.

  50. Learning Check Indicate whether a bond between the following is 1) Ionic 2) Covalent ____A. sodium and oxygen ____B. nitrogen and oxygen ____C. phosphorus and chlorine ____D. calcium and sulfur ____E. chlorine and bromine

More Related