Chapter Four

1. Chapter Four Chemical Bonding: The Ionic Bond Model

2. Chemical Bonding: The Ionic Bond Modelcont’d Chemical Compounds • _________ Compounds • Usually Metal and Nonmetal ions • ________ Bonds • Solids, high melting, conducts electricity (molten or in solution) • __________ Compounds • Usually between Atoms of same Element or between atoms of nonmetals • __________ Bonds • Gases, liquids, or low melting solids, non-conductor

3. Chemical Bonding: The Ionic Bond Modelcont’d • What are chemical bonds? • Chemical bond: attractive _______ holding two or more atoms together. • Ionic bond results from the attraction of ________ and ____________ ions • Usually, a metal forms the ________ ion and a nonmetal forms the _________ ion • Covalent bond results from _________ electrons between the atoms. • Usually found between ____________

4. Chemical Bonding: The Ionic Bond Modelcont’d Chapter 4 Focus is on Ionic Bonds • Bond formed through the ________ of one or more electrons from one atom or group of atoms to another atom or group of atoms • Metals tend to give up electrons and form ______ • Non-metals tend to accept electrons and form _________ • The Ionic Bond is formed by the attraction between the _____ and ____ charges

5. Chemical Bonding: The Ionic Bond Modelcont’d Recall Chapter 3 Topic Electron Configurations Electrons residing in outer most energy level are called distinguishing or valence electrons Valence electrons determine chemical properties or how atoms of one particular element interact (give up or gain electrons) with atoms of another element

6. Chemical Bonding: The Ionic Bond Modelcont’d • Valence Electrons: • Example: Mg: ________________________ • Example: Cl: ____________________________ • An easy way to determine how many valence electrons an element has: • The number of valence electrons is _______ to the group number (for elements in the s and p blocks)

7. Chemical Bonding: The Ionic Bond Modelcont’d

9. Chemical Bonding: The Ionic Bond Modelcont’d How many valence electrons do the following elements have? • Na • Al • S • Cl

10. Chemical Bonding: The Ionic Bond Modelcont’d Lewis Symbol Is the chemical symbol of an element surrounded by dots equal in number to the number of __________ electrons present in atoms of the element Elements in the same group have the same number of ___________ electrons The number of __________ electrons for elements in the same group is the same as the “A” Group number The maximum number of ____________ electrons for any element is eight (H and He exceptions) Eight ____________ electrons is most stable and results in the rule of eight or octet rule to produce a noble gas electron configuration

11. Chemical Bonding: The Ionic Bond Modelcont’d • Fig. 4.2 Gilbert Newton Lewis was one of the foremost chemists of the 20th century. Edgar Fahs Smith Collection, University of Pennsylvania Library

12. Chemical Bonding: The Ionic Bond Modelcont’d

13. Chemical Bonding: The Ionic Bond Modelcont’d • Fig. 4.3 Loss of an electron from a sodium atom leaves it with one more proton than electrons, so it has a net electrical charge of +1.

14. Chemical Bonding: The Ionic Bond Modelcont’d Fig. 4.4 a-c (a,b) Two-dimensional cross section and a three-dimensional view of sodium chloride. (c) sodium chloride crystals

15. Chemical Bonding: The Ionic Bond Modelcont’d Focus on Mg and Cl

16. Chemical Bonding: The Ionic Bond Modelcont’d Let’s look at Mg. Its electron configuration is 1s22s22p63s2. • If it loses ____ electrons to become ________, it will have the electron configuration 1s22s22p6 • ____ Valence Electrons! • If it gains ____ electrons to become ______, it will have the electron configuration 1s22s22p63s23p6 • ___ Valence Electrons! • The question is which is easier? To lose TWO electrons or to gain SIX? • Losing two: Therefore, Mg tends to form Mg2+ ions

17. Chemical Bonding: The Ionic Bond Modelcont’d Let’s look at Cl. Its electron configuration is 1s22s22p63s23p5. • If it loses ____ electrons to become ______, it will have the electron configuration 1s22s22p6 • ___ Valence Electrons! • If it gains _____ electron to become ______, it will have the electron configuration 1s22s22p63s23p6 • ___ Valence Electrons! • The question is which is easier? To lose SEVEN electrons or to gain ONE? • Losing ONE: Therefore, Cl tends to form Cl- ions

18. Chemical Bonding: The Ionic Bond Modelcont’d • So, Mg will form Mg2+ ions, and Cl will form Cl- ions. • Opposite charges attract: • Mg2+ + 2Cl- MgCl2

19. Chemical Bonding: The Ionic Bond Modelcont’d Isoelectronic Species Are atoms or ions that have the ______ number and configuration of electrons. N3- O2- F1- Na1+ Mg2+ Al3+ All are isoelectronic with ______ and all have the electronic configuration 1s2 2s2 2p6

20. Chemical Bonding: The Ionic Bond Modelcont’d Formula Units The smallest whole number repeating ratio of ions present in an ionic compound that results in charge neutrality. NaCl MgCl2 AlCl3 Na2O MgO Al2O3

21. Chemical Bonding: The Ionic Bond Modelcont’d • Fig. 4.5 Cross section of the structure of the ionic solid NaCl.

22. Chemical Bonding: The Ionic Bond Modelcont’d • The number of electrons an atom loses or gains is related to its position on the periodic table.

23. Chemical Bonding: The Ionic Bond Modelcont’d • Group IA metals • Group IIA metals • Group IIIA metals • Group VIIA nonmetals • Group VIA nonmetals • Group VA nonmetals

24. Chemical Bonding: The Ionic Bond Modelcont’d • Fig. 4.8 Periodic table in which the metallic elements that exhibit a fixed ionic charge are highlighted.

25. Chemical Bonding: The Ionic Bond Modelcont’d Writing Formulas for compounds • For compounds, a neutral species, the number of electrons lost and gained must be _______. • The amount of positive charge must _______ the amount of negative charge. • Formulas of ionic compounds • Symbol for the positive ion is always written first • The charges on the ions are _______ shown in the formula • The _____________ in the formula give the combining ratio for the ions

26. Chemical Bonding: The Ionic Bond Modelcont’d It may be helpful to initially write in the charges of each ion, then determine the number of + and – ions that would balance out the charges. K1+ S2- Al3+ O2-

27. Chemical Bonding: The Ionic Bond Modelcont’d Naming Ionic Compounds • First word of name: • Name of ___________ (first element in formula) • If the metal can form more than one _________, then the charge is indicated in parentheses in the name. • Examples: Cu+ = copper (I); Cu2+ = copper (II). • Second word of name: • Name of ________ (second element in formula). Write the _____ of the name of the nonmetal ion with the –ide ending

28. Chemical Bonding: The Ionic Bond Modelcont’d

29. Chemical Bonding: The Ionic Bond Modelcont’d What is the name or formula for each of the following? • K3N • AuCl3 • PbS

30. Chromium (III) oxide • Iron (II) oxide • Magnesium Chloride

31. Chemical Bonding: The Ionic Bond Modelcont’d Thus far these have been compounds formed by Metal Cations and Non-metal Anions. An ionic compound in which one element present is a metal and the other element present is a nonmetal is called a “_________ Ionic Compound”

32. Chemical Bonding: The Ionic Bond Modelcont’d • Monatomic ion • An ion formed from a _______ atom through loss or gain of electrons • Examples: Na+, S2-, etc. • Polyatomic ion • An ion formed from a ______ of atoms (held together by covalent bonds) and as a whole becomes charged through loss or gain of electrons • Can be the positive or the negative ion in an ionic compound

33. Chemical Bonding: The Ionic Bond Modelcont’d

34. Chemical Bonding: The Ionic Bond Modelcont’d • Give the formulas and names of the ionic compounds formed between the following ions: • NH4+ & PO43- • Na+ & NO31- • NH4+ and O2-

35. NH4+ and PO43- • Li+ and CO32- • Mg2+ and NO31-

36. Chemical Bonding: The Ionic Bond Modelcont’d