Ionic Bonding

1. Ionic Bonding Writing Formulae Naming Compounds

2. Atoms and Ions • Chemical Bond —force that holds 2 atoms together • Atoms are neutral=same number of protons as electrons • Ion—atom that has lost or gained electrons (it has a charge of + or -)

3. Remember • Only electrons can move • Atoms gain or lose electrons to achieve a noble gas configuration • To be stable

4. Keeping Track of Electrons • The electrons responsible for the chemical properties of atoms are those in the outer energy level. • Valence electrons - The s and p electrons in the outer energy level. • Core electrons -those in the energy levels below.

5. Keeping Track of Electrons • Atoms in the same column have the same outer electron configuration. • Have the same valence electrons. • Easily found by looking up the group number on the periodic table. • Group 2A - Be, Mg, Ca, etc.- • 2 valence electrons

6. Electron Dot diagrams • A way of keeping track of valence electrons. • How to write them • Write the symbol. • Put one dot for each valence electron • Don’t pair up until they have to X

7. The Electron Dot diagram for Nitrogen • Nitrogen has 5 valence electrons. • First we write the symbol. N • Then add 1 electron at a time to each side. • Until they are forced to pair up.

8. Write the electron dot diagram for • Na • Mg • C • O • F • Ne • He

9. Electron Configurations for Cations • Metals lose electrons to attain noble gas configuration. • They make positive ions. • If we look at electron configuration it makes sense. • Na 1s22s22p63s1 - 1 valence electron • Na+ 1s22s22p6 -noble gas configuration

10. Electron Dots For Cations • Metals will have few valence electrons Ca

11. Electron Dots For Cations • Metals will have few valence electrons • These will come off Ca

12. Electron Dots For Cations • Metals will have few valence electrons • These will come off • Forming positive ions Ca+2

13. Electron Configurations for Anions * • Nonmetals gain electrons to attain noble gas configuration. • They make negative ions. • If we look at electron configuration it makes sense. • S 1s22s22p63s23p4 - 6 valence electrons • S-2 1s22s22p63s23p6 -noble gas configuration.

14. Electron Dots For Anions • Nonmetals will have many valence electrons. • They will gain electrons to fill outer shell. P P-3

15. Stable Electron Configurations • All atoms react to achieve noble gas configuration. • Noble gases have 2 s and 6 p electrons. • 8 valence electrons . • Also called the octet rule. Ar

16. Compounds • 2 atoms bonded together • Follow the Law of Definite Proportion—have a constant composition—the same # of atoms every time

17. 3 Types of compounds • Ionic Bonds • Covalent or Molecular Bonds • Metallic Bonds

18. Ionic Bonds • Made by transferring electrons • Made of cations (metals) and anions (nonmetals) • The e- lost by the cation is gained by the anion • The cations and anions surround each other • Smallest piece is a Formula Unit

19. Ionic Bonding

20. Ionic Bonding • Anions and cations are held together by opposite charges. • Packed into a regular repeating pattern that balances the forces of attraction and repulsion between the ions forming a crystal • Very strong bond • Ionic compounds are called salts.

21. Properties of Ionic Compounds • Crystalline structure. • A regular repeating arrangement of ions in the solid. • Ions are strongly bonded. • Structure is rigid. • High melting points- because of strong forces between ions.

22. Crystalline structure

23. Do they Conduct? • Conducting electricity is allowing charges to move. • In a solid, the ions are locked in place. • Ionic solids are insulators. • When melted, the ions can move around. • Melted ionic compounds conduct. • First get them to 800ºC. • Dissolved in water they conduct.

24. + - + - - + - + + - + - - + - + Ionic solids are brittle

25. - + - + - + - + + - + - - + - + Ionic solids are brittle • Strong Repulsion breaks crystal apart.

26. Writing the formula for compounds and Naming compounds Learning to speak the language

27. Chemical Formula • Shows the kind and number of atoms in the smallest piece of the substance • Nicotine • C10H14N2

28. For Ionic Compounds: Systematic Naming • There are too many compounds to remember the names of them all • Compound-2 or more elements chemically combined • Pure substance • Name tell how many and what kind of atoms

29. Remember –Ionic Bonds • Anions and cations held together by opposite charges • Called salts • Simplest ratio is called formula unit • Bond is formed by transfer of electrons • Electrons are transferred to achieve a noble gas configuration

30. Ionic bonding or Formula Unit • Shows lowest whole # ratio of atoms in the crystal lattice • NaCl • MgCl2

31. Charges on Ions • You can tell charge of an atom by its location • Elements in the same group have similar properties including the charge when they are ions • Oxidation number -the charge of the ion

32. +1 +2 +3 -3 -2 -1

33. Naming ions • We will use the systematic way. • Cation- if the charge is always the same (Group A) just write the name of the metal. • Transition metals can have more than one type of charge. • Indicate the charge with roman numerals in parenthesis.

34. Name these • Na+1 • Ca+2 • Al+3 • Fe+3 • Fe+2 • Pb+2 • Li+1

35. Write Formulas for these • Potassium ion • Magnesium ion • Copper (II) ion • Chromium (VI) ion • Barium ion • Mercury (II) ion

36. Naming Anions • Anions are always the same. • Change the element ending to – ide • F-1 Fluorine

37. Naming Anions • Anions are always the same. • Change the element ending to – ide • F-1 Fluorine  Fluor + ide = Fluoride

38. Name these • Cl-1 • N-3 • Br-1 • O-2 • Ga+3

39. Write these • Sulfide ion • iodide ion • phosphide ion • Strontium ion

40. Polyatomic ions • Group of atoms covalently bonded together that gain or lose an electron • LEARN YOU POLYATOMIC IONS! • Oxyanion –polyatomic ions composed of an element bonded to one or more oxygen atoms • Ate ions • Ite ions • Per • hypo

41. Sulfate SO4-2 Sulfite SO3-2 Carbonate CO3-2 Chromate CrO4-2 Dichromate Cr2O7-2 Phosphate PO4-3 Phosphite PO3-3 Ammonium NH4+1 Polyatomic ions

42. S-2 monatomic Sulfide ion N-3 monatomic Nitride ion Bromide Selenide SO4-2 polyatomic Sulfate ion NO3- polyatomic Nitrate PO4-3 Phosphate ion Monatomic vs Polyatomic anions

43. Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • To write the names just name the two ions. • Easy with Representative elements. • Group A • NaCl = Na+ Cl- = sodium chloride • MgBr2 = Mg+2 Br- = magnesium bromide

44. Naming Binary Ionic Compounds • The problem comes with the transition metals. • Need to figure out their charges. • The compound must be neutral. • same number of + and – charges. • Use the anion to determine the charge on the positive ion.

45. Naming Binary Ionic Compounds • Write the name of CuO • Need the charge of Cu • O is -2 • copper must be +2 • Copper (II) chloride • Name CoCl3 • Cl is -1 and there are three of them = -3 • Co must be +3 Cobalt (III) chloride

46. Naming Binary Ionic Compounds • Write the name of Cu2S. • Since S is -2, the Cu2 must be +2, so each one is +1. • copper (I) sulfide • Fe2O3 • Each O is -2 3 x -2 = -6 • 3 Fe must = +6, so each is +2. • iron (III) oxide

47. Naming Binary Ionic Compounds • Write the names of the following • KCl • Na3N • CrN • Sc3P2 • PbO • PbO2 • Na2Se

48. Ternary Ionic Compounds • Will have polyatomic ions • At least three elements • name the ions • NaNO3 • CaSO4 • CuSO3 • (NH4)2O

49. Ternary Ionic Compounds • LiCN • Fe(OH)3 • (NH4)2CO3 • NiPO4

50. Writing Formulas • The charges have to add up to zero. • Get charges on pieces. • Cations from name on table. • Anions from table (ide) or polyatomic. • Balance the charges by using subscripts.