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Ionic Bonding Part I

Ionic Bonding Part I. An Elemental Love Story. Demo. Burning string demo Clean string vs Sugar soaked string vs Salt soaked string Any difference?. Research Mission. For this week, you will read articles about: Iodine deficiency disorder Pros and cons of fluoride

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Ionic Bonding Part I

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  1. Ionic Bonding Part I An Elemental Love Story

  2. Demo • Burning string demo • Clean string vs Sugar soaked string vs Salt soaked string • Any difference?

  3. Research Mission For this week, you will read articles about: • Iodine deficiency disorder • Pros and cons of fluoride • The importance of potassium • The dangers of chromium After gathering information, your group will present what you learned and how it relates to ions and ionic bonding.

  4. Before we dive in • What is a chemical bond? • What are three main different types of bonds? • Why do elements form ions? • What is a cation? • What is an anion?

  5. Q: How do elements combine to form compounds? A: Compounds have different forces that hold groups of atoms together and make them function as a unit called bonds. Bonds

  6. Bonds Bonds come in three main varieties: • Metallic bonds – when metal cations bond they share a sea of delocalized electrons. • Ionic bonds – transfer of electrons between metals and non metals • Covalent bonds – sharing of electrons between two nonmetals

  7. Metallic Bonding Strong forces of attraction are responsible for the high melting point of most metals.

  8. Metallic Bonding • The chemical bonding that results from the attraction between metal cations and the surrounding sea of electrons • Vacant p and d orbitals in metal's outer energy levels overlap, and allow outer electrons to move freely throughout the metal • Valence electrons do not belong to any one atom

  9. Properties of Metals • Metals are good conductors of heat and electricity • Metals are malleable • Metals are ductile • Metals have high tensile strength • Metals have luster

  10. Metal Alloys Alloys: some metal atoms replaced by others of similar size.

  11. Ionic bonding Ionic compounds bond in repeating 3-dimensional patterns with alternating positive and negative ions called crystal lattice.

  12. Ionic Crystal Lattice Shapes

  13. Ionic bonding All salts are ionic compounds and form crystals. NaCl forms the simplest cubic structure

  14. Properties of Ionic Compounds

  15. Properties of Ionic Compounds • Lab! • We will be examining the properties of ionic compounds next double with a lab. • In the meantime, we will move onto how and why ions bond.

  16. Great BBC video on ions • http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/ionicact.shtml

  17. Know our ions inside and out • In order to be successful with ionic bonding, you need to know what ion each element in the s and p block will form. • Practice on the Ion worksheet grid in the packet

  18. The Octet Rule – Ionic Compounds • Ionic compounds form so that each atom, by gaining or losing electrons, has an octet of electrons in its highest occupied energy level. • Ionic bonds form between metals and nonmetals! • Metals lose electrons to form positively-charged cations • Nonmetals gains electrons to form negatively-charged anions

  19. Ionic Bonding:Sodium Chloride Example • Sodium has 1 valence electron • Chlorine has 7 valence electrons • An electron transferred gives each an octet Na:1s22s22p63s1 Cl:1s22s22p63s23p5

  20. Ionic Bonding

  21. Ionic Bonding:Sodium Chloride Example This transfer forms ions, each with an octet: Na+1s22s22p6 Cl-1s22s22p63s23p6

  22. Ionic Bonding:Sodium Chloride Example The resulting ions come together due to electrostatic attraction (opposites attract): Na+ Cl- The net charge on the compound must equal zero

  23. Writing Ionic Compounds with Electron Dot Diagrams

  24. Drawing Ionic compounds • How would these elements bond? Li F K Br

  25. Drawing Ionic Compounds • Not all relationships are 1:1 with sharing of valence electrons. • Sometimes you need more of one element than the other to make a neutral compound

  26. Drawing Ionic Compounds • How would these elements bond? Mg Br

  27. Draw the ionic compounds How about K S

  28. Criss Cross method! Example: Aluminum sulfide 1. Write the formulas for cation and anion, including CHARGES! 2. Do charges balance? 3. If not, use criss-cross method to balance subscripts. Al3+ S2- 2 3 Not balanced! Now balanced. = Al2S3

  29. Criss Cross Method! Example: Beryllium chloride 1. Write the formulas for cation and anion, including CHARGES! Be2+ Cl- 2 Now balanced. 2. Do charges balance? Not balanced! 3. Balance charges, if necessary, using subscripts. Use criss-cross method to balance subscripts. = BeCl2

  30. Try the criss cross method Magnesium chloride: Magnesium loses two electrons and each chlorine gains one electron Mg Cl Sodium oxide: Each sodium loses one electron and the oxygen gains two electrons Na O Aluminum sulfide: Each aluminum loses two electrons (six total) and each sulfur gains two electrons (six total) Al S

  31. Naming Ionic Compounds You may have noticed that the name of the nonmetal in the previous compounds sounded different (chloride instead of chlorine, oxygen inside of oxide) Can you think of what might be a naming rule for ionic compounds? What’s the order we use? Do any of the names change?

  32. Naming Ionic Compounds • Name the cation first and then the anion • Cations – use the name of the element • Anions – use the name of the nonmetal but change the ending to an –ide

  33. Practice! Let’s try writing our predicting ion charges and and writing ionic compounds using the criss cross method

  34. Ionic Bonding Wrinkles Polyatomic molecules and METALS WITH MULTIPLE IONS

  35. Polyatomic ions • Many ionic compounds contain polyatomic ions which are ions made up of more than one atom. • Polyatomic ions are atoms that are covalently bonded together and act as an individual ion. • Because it exists as a unit, DO NOT change the subscripts within the ion. • In Ionic Compounds, you put ( ) around them

  36. Polyatomic ions • You will not be asked to memorize the polyatomic ions, but… • You do need to be able to recognize them • And use a resource to determine its ionic charge • So that you can balance and write ionic compounds! • http://www.youtube.com/watch?v=MJZeZvDxcx8

  37. Polyatomic Ion Names • CO32- carbonate • OH – hydroxide • SO42- sulfate • PO43- phosphate • NO3– nitrate • ClO3– chlorate • NH4+ ammonium

  38. Writing Ionic Compound with polyatomics Example: Zinc hydroxide 1. Write the formulas for cation and anion, including CHARGES! ( ) Zn2+ OH- 2 Now balanced. 2. Do charges balance? Not balanced! 3. Balance charges , if necessary, using subscripts. Use () if more than one polyatomic ion. Use criss-cross method to balance subscripts. = Zn(OH)2

  39. Example: Barium nitrate 1. Write the formulas for cation and anion, including CHARGES! ( ) Ba2+ NO3- 2. Do charges balance? 2 3. Balance charges , if necessary, using subscripts. Use () if more than one polyatomic ion. Use criss-cross method to balance subscripts. Now balanced. Not balanced! = Ba(NO3)2

  40. Writing Ionic Compound with polyatomic molecules Example: Ammonium sulfate (note the 2 word name) ( ) NH4+ SO42- 1. Write the formulas for cation and anion, including CHARGES! 2 Now balanced. 2. Do charges balance? Not balanced! = (NH4)2SO4 3. Balance charges , if necessary, using subscripts. Use () if more than one polyatomic ion. Use criss-cross method to balance subscripts.

  41. METALS WITH MULTIPLE IONS Up until now, we’ve only been working with ions from the s and p block and ignoring d-block This is because d-block metals as well as other metals can often form more than one type of ion Again, you will not have to memorize these ions, but be able to use a resource to write ionic compounds with them.

  42. METALS WITH MULTIPLE IONS • For those metals it is important to represent which ion it is with a roman numeral. • If it is +1 you put a (I) after the name of the metal • If it is +2 it is a (II) after the name of the metal • If it is a +3, you put a (III) after the name of the metal • You include this roman numeral in the name ONLY for metals that form multiple ions! For example: NiBr2 would be Nickel (II) Bromide

  43. Roman numeral review!

  44. Practice! Now, let’s practice writing ionic compounds with either polyatomic ions or METALS WITH MULTIPLE IONS

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