Bonding Between Atoms

1. Bonding Between Atoms

2. Why Do Atoms Form Bonds • To get a stable octet of valence electrons. • Called a “noble gas configuration”

3. Changes in Energy Exothermic = Bond Forms • Energy is released when bonds form. • Exothermic • Lower energy = more stable Endothermic = Bond Breaks

4. Bond Formation is EXOTHERMIC

5. Major Types of Bonds

6. IONIC BOND • Metal and Nonmetal • valence e- transferred

7. COVALENT BOND • All nonmetals • valence e- shared

8. Metallic Bonding • Pure metals & alloys • Valence electrons become “mobile” between all the atoms.

9. What Type of Bonding? • _________CaCl2 • _________C6H12O6 • _________ CO2 • _________ Fe • _________ H2O • _________ Al(NO3)3 • _________ Mg • _________ NH3

10. Lewis Dot Diagrams of Atoms • Show valence electrons involved in bonding

11. Lewis Dot Diagrams of Ions • Positive Ions (cations): lose outer shell valence to get stable octet. • Negative Ions (anions): gain electrons to complete outer shell octet. Do Bonding Packet Pgs 4, 5, 6

12. Ionic Bonding Crash Course: https://www.youtube.com/watch?v=QXT4OVM4vXI

13. Ionic Bonding • Happens between metals and nonmetals What are Ionic Bonds? (1:30) https://www.youtube.com/watch?v=zpaHPXVR8WU

14. Electronegativity Difference • Ionic compounds: large differences in atomic EN values ( > 1.7) Greater EN diff. = more “Ionic Character”.

15. Ex: EN Values • Metal Na = 0.9 • Nonmetal Cl = 3.2 • Nonmetal with higher EN “takes” electron(s) from metal

16. Atoms Become Ions • Metals Lose Electrons: • become (+) ion • Ex: Mg is 2-8-2 • Loses 2 electrons to become Mg+2 2-8 • Nonmetals Gain Electrons: usually take top (-) charge • become (–) ion • Ex: Cl is 2-8-7 • Gains 1 electron to become Cl-1 2-8-8

17. Ionic Bond = Electron Transfer • As ions form, an exchange or transfer of electrons happens. Lithium (metal) 2-1 Fluorine (nonmetal) 2-7

18. Positively and negatively charged ions form and attract each other due to OPPOSITE CHARGES. IONIC BOND • Forming Table Salt :6 minutes • http://science360.gov/obj/video/c8b6ed58-5791-4fc1-8619-62fd8d99d9d0/atoms-bond-ionic-bonds - ion + ion

20. They transfer enough electrons so that all get a stable octet of valence!

21. Drawing Lewis Dot Diagrams of Ionic Compounds

22. Ionic compounds have uniform crystalline lattice structure. https://www.youtube.com/watch?v=lhC42qxk5kQ&safe=active

23. Can you identify an ionic compound from a covalent? • Ionic = Metal with nonmetals • _____________MgBr2 • _____________Ca(NO3)2 • _____________P2O5 • _____________SiO2 • _____________Na2S • _____________H2S

24. Ionic Compounds are Neutral “Subscripts” show ratio of ions Total positive and negative charges must balance Compound is electrically neutral.

25. Writing Neutral Ionic Formulas • Write symbols of elements with charge • Criss-Cross charges if necessary to balance the formula • Put parenthesis around polyatomic ions if more than one in formula • Simplify if needed. Tutorial on writing ionic formulas 9 min http://www.youtube.com/watch?v=vscoYh6m46M

26. Stock System for Naming Ionic Compounds • Binary: Contain ions of 2 elements Ex: MgCl2, Al2O3, NaCl

27. Naming Binary Ionics • Name metal • Name nonmetal with “-ide” ending. • Note: Name never indicates # of ions • Ex: NaCl, MgBr2, CaO, Al2S3 Writing Ionic Formulas: (3:22) https://www.youtube.com/watch?v=vfYnhnfdsD0

28. Ternary Ionics: Contain 3 elements • Polyatomic ion present. • Note: Elements inside the polyatomic ion are covalently bonded (all nonmetals). • These compounds contain both ionic and covalent bonds!! MgSO4

29. Naming Ternary Ionics (with polyatomic) • Name Metal • Name polyatomic ion • If two polyatomics, name them both • Ex: NaNO3, Ca3(PO4)2, NH4Cl Ionics with Polyatomic Ions: (3:46) https://www.youtube.com/watch?v=JylJwHryeSU

31. Why does the 3rdcompound use a Roman Numeral in it’s name?

32. When to Use a Roman Numeral • Roman numerals are used when the metal can have more than one possible charge. • Roman numeral indicates the charge the metal takes in that compound and must be indicated in the name Ex: NiBr2 Nickel II Bromide NiBr3 Nickel III Bromide

33. Name the following ionic compounds: • Fe(NO3)3 ____________________ • NaF _________________________ • Cu3P ________________________ • Al2(SO4)3 ____________________

34. Write the correct formula for: • _____________cobalt III oxide • _____________magnesium sulfide • _____________ lead II nitrate • _____________ calcium phosphate

35. Properties of Ionic Compounds

36. High Melting Point Attraction between ions is very strong. Requires large amount of heat energy to separate ions and make solid melt. Higher MP than covalents

37. Solubility in Water • Most ionics will dissolve in water, or be “soluble”. • When dissolved in water they are “aqueous” Ex: NaCl (aq)

38. Water is a “polar molecule”. • Acts like magnet to pull ions apart and into solution. • Ions are now “dissociated” or “hydrated” ions. • http://youtu.be/EBfGcTAJF4o

39. Conductivity • Ionic compounds conduct when ions are “mobile” or free to move about. • Ionic compounds conduct when: • Molten (melted or liquid) (l) • Aqueous (aq)

40. Molten Ionics can Conduct!

41. Conductivity DO NOT conduct when solid as the ions locked in place. Most covalents do not conduct

42. Which compound has the highest Melting point? KCl or SO2 • Which substances conduct electricity? NaCl (s) CO2 (g) MgBr2 (l) C6H12O6 (s) LiNO3 (aq)

43. Lattice Energy (Honors) • Energy released when ionic bond is formed • The more energy, the more stable and stronger the bond. • Related to Coulombic Attraction • Variables that Determine its Magnitude: • Atomic Size • Ion Charge • See Honors Packet Pages

44. Crash Course Chemistry: Nomenclature (only watch first 6 minutes, skip section on naming acids for now) http://www.youtube.com/watch?v=mlRhLicNo8Q Dancing Queen: Song about Ionic vs Covalent Bonding http://www.youtube.com/watch?v=QIfTT-_-xLo Crash Course: Atomic Hookups http://www.youtube.com/watch?v=QXT4OVM4vXI