1 / 42

Unit 8: Ionic and Metallic Bonding

Unit 8: Ionic and Metallic Bonding. REVIEW: Electron dot structure. Only shows valence electrons (as dots) # of valence electrons = last digit of group number for main group (representative) elements. No more than 2 dots per side, for a total of 8 dots. Electronegativity.

geoff
Download Presentation

Unit 8: Ionic and Metallic Bonding

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. Unit 8: Ionic and Metallic Bonding

  2. REVIEW: Electron dot structure • Only shows valence electrons (as dots) • # of valence electrons = last digit of group number for main group (representative) elements. • No more than 2 dots per side, for a total of 8 dots

  3. Electronegativity • Describes the relative ability of an element’s atoms to attract electrons in a chemical bond. • The halogens have the highest EN because they only need one more electron to complete an octet and achieve chemical stability.

  4. Ionization energy • The amount of energy required to remove an electron from an atom. • The noble gases, with a stable electron configuration, have the highest IE. • The alkali metals have the lowest IE meaning it is pretty easy to remove an electron from one of these atoms.

  5. Formation of Ions • Atoms will gain or lose valence electrons so they have an electron configuration like the NEAREST noble gas. ***Why would elements want to be like the Noble Gases?

  6. Isoelectronic • Term used to describe elements that have the same electron configuration

  7. Copy Cat Sulfur wants to be like Argon (1s22s22p63s23p6) Sulfur Atom 1s22s22p63s23p4 16 Protons 16(+) 16 Electrons 16 (-) 0 No charge Sulfur has 6 valence e- and will gain 2 more to complete an octet. The result is a: Sulfur Anion 1s22s22p63s23p6 16 Protons 16 (+) 18 Electrons 18 (-) 2- Charge The sulfur anion, S-2, has the same electron configuration as Argon. S-2 and Ar are isoelectronic.

  8. Copy Cat Sodium wants to be like Neon (1s22s22p6) Sodium Atom 1s22s22p63s1 11 Protons 11(+) 11 Electrons 11 (-) 0 No charge Sodium has 1 valence e- and loses it so that its 2nd energy level has 8 valence e- Sodium Cation 1s22s22p6 11 Protons 11(+) 10 Electrons 10 (-) 1+ Charge Na+1and Ne are isoelectronic.

  9. Charge of Ions • called OXIDATION NUMBER • Related to the number of electrons that are lost or gained when an atom becomes an ion Group 14 +4 -3 Group 13 +3 Group 15 Group2 Group 16 +2 • -2 Group 1 +1 -1 Group 17 0 Group 18

  10. Oxidation numbers • Same for all elements in a group or family • (+) means that the atom loses electrons when forming a cation; formed by metals • (-) means that the atom gains electrons when forming an anion ; formed by nonmetals • The Noble Gases have oxidation number of zero because they are nonreactive and do not lose or gain electrons.

  11. Transition Metals and Charge MULTIVALENT: transition metals that form ions with multiple charges. Ex. Fe2+ or Fe3+ Ex. Mn2+ or Mn5+ or Mn7+ MONOVALENT: T. metals that DO NOT form ions with more than one charge. Ag1+, Zn2+, Cd2+, Al3+ (Remember AZCA, they also make a stair step)

  12. Classifying metals: • Type 1 metal (MONOVALENT): Group 1,2 and Al, Zn, Cd, Ag • These metals only have 1 charge • Al is +3 Zn and Cd are +2 Ag is +1 • Type 2 metal (MULTIVALENT): all metals that are not type 1 metals • Can have 2 or more charges • Must use a Roman Numeral in the name

  13. POLYATOMIC ION (PAI) • Two or more nonmetal atoms bonded together • Act as a single unit with a net charge • LISTED ON YOUR STAAR CHART • Chlorate, ClO3-1 is the same as (ClO3)-1 which means that 1 chlorine atom is bonded to 3 oxygen atoms and as a group • it has a charge of -1

  14. Bonding • A chemical bond is an electrostatic force that holds two atoms together; • involves valence electrons • Electrostatic: refers to the attraction between opposite charges • Bonds form so that atoms are more stable than they were when unbonded.

  15. Ionic bond • Formed by the transfer of electrons between a metal and a nonmetal • # of e- lost by metal = # of e- gained by nonmetal

  16. The greater the difference between eN values of 2 atoms, the more ionic the bond will be. 0.8- 4.0 = 3.2 very ionic

  17. Ionic Bond Na+Cl- http://www.chm.bris.ac.uk/pt/harvey/gcse/ionic.htm

  18. Ionic BondsMetal to Nonmetal Na Cl Sodium gives Chlorine 1 electron. NaCl Sodium Chlorine SodiumChloride

  19. Ionic Bonds Strong electrostatic force (positive-negative) in ionic compounds makes a strong ionic bond. How does the strong ionic bond affect the properties of ionic compounds? Formula unit : smallest unit of an ionic compound; lowest whole number ratio of ions represented in an ionic compound

  20. Properties of ionic compounds • high melting and boiling points • hard solids • good conductors – in aqueous solutions and when molten • have a crystal lattice structure Ions are here

  21. WRITING FORMULAS FOR IONIC COMPOUNDS : • Write the symbol for each ion. *** Positive ion goes first*** • Write the oxidation number for each ion above the symbol. *For type 2metals, the Roman numeral after the metal tells you the oxidation number

  22. Criss-cross the oxidation numbers (do not take the + or -). These numbers become the subscripts. 4. If a subscript is needed for the PAI, you must enclose it in parentheses first, then write the subscript outside of the parentheses.

  23. Example: Write the formula for the compound that contains aluminum and sulfur.

  24. Example: Write the formula for the compound that forms when sodium and oxygen combine.

  25. Example: Write the formula for iron (II) chloride. *Reminder: What does the Roman Numeral tell you?

  26. Example: Write the formula for the compound that contains calcium and phosphate.

  27. WRITING NAMES FOR IONIC COMPOUNDS • Write the name of the metal first. • IF THE METAL IS A TYPE 2 METAL, write the oxidation number of the metal in parentheses. • (You will have to work backwards from the subscripts to determine the oxidation number.) • Example: Fe2O3 un-criss-cross the subscripts • Iron is +3 Oxygen is -2

  28. Write the name of the nonmetal second 4. Change the ending to “ide.” 5. IF EITHER PART OF THE COMPOUND IS A POLYATOMIC ION: • Write the name of the polyatomic nonmetal from the chart. • DO NOT CHANGE THE ENDING OF THE PAI.

  29. Example: Write the name for the compound that contains lithium and nitrogen.

  30. Example: Name this compound: NiF2

  31. Example: Name this compound: Ca(C2H3O2)2

  32. Metallic bonding http://www.launc.tased.edu.au/online/sciences/PhysSci/pschem/metals/Metals.htm

  33. Metallic bonds Metallic bonding is the strong attraction between closely packed positive metal ions and a 'sea' of delocalized electrons. What are the properties of metals? How does metallic bonding affect the properties of metals? http://www.bbc.co.uk/schools/gcsebitesize

  34. Metallic bonds What property of metals is illustrated above?

  35. Metallic bonding

  36. Alloys • a mixture of elements that has metallic properties • Examples: • Steel is an alloy of iron that contains carbon • brass (copper and zinc) • dental amalgam (mercury, silver, tin) • sterling silver (silver and copper)

  37. Properties of metals • Here’s another one. Enjoy • Video clip

  38. Percent Composition Percent Composition (% mass): the percentage by mass of each element in a compound

  39. % Composition Practice What is the percent of Li and O in Li2O?

  40. What is the percent of each element in Na2SO3?

  41. How much sodium is in 25 grams of Na2SO3 ?

More Related