Ionic, Covalent and Metallic Bonding Lab NAME:___________________________DATE:_____________PERIOD:_______ Background: Bonding can be ionic, covalent or metallic. An ionic bond occurs when elements of very different electronegativities combine. This happens when a metal that has a very low electronegativity comes in contact with a nonmetal that has a very high electronegativity. Electronegativity is the ability to attract and pull on electrons. The metal has little ability to pull on the electron while the nonmetal has a high ability to pull on the electron. Therefore the nonmetal will pull the electron away from the metal forming an ionic bond! Ionic Bond: Metal and Nonmetal Na + Cl Na+1 + Cl-1 Covalent bonding occurs when elements of similar electronegativity combine. This happens when nonmetals combine with other nonmetals creating a covalent bond. Covalent means “sharing” of electrons. If the sharing of the electrons in the bond is “equal” then a nonpolar covalent bond forms. If the sharing of the electrons in the bond is “unequal” then a polar covalent bond forms. Nonpolar Covalent: Diatomic elements! Electrons are equally shared. Both atoms have the same pull on the electrons. H● + ●H H●--●H Polar Covalent: Two different nonmetals! Electrons are unequally shared. One atom has a greater pull on the electrons. C● + ●O C ●--●O Metallic bonding occurs in metals. In metals the electrons are not tied to a specific nucleus so they are free to move creating a model that looks like an array of positive nuclei surrounded in a sea of electrons. It is important to understand that we use the term metallic bonding and not metallic bond. The bonding in metals is collective and not a single bond between one metal atom and another metal atom. ---------------------------------------------+++++++++++++++++++++++ ---------------------------------------------Procedure: Visit each lab station and record the compound formula or element symbol for each sample. Then decide if the sample represents an ionic compound, covalent compound or a metal. Then decide the bonding type and bonding description for each sample. Data: Sample Number Formula Or Symbol Compound Or Element Ionic, Covalent or Metallic Transfer of eSharing of eSea of e- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Conclusion: 1) ________________ is the atom’s ability to pull or attract electrons. 2) A ______________ bond forms between a metal atom and a nonmetal atom. 3) A ______________ bond forms between two nonmetallic atoms. 4) _________ bonding occurs in metals. The electrons move freely as in a “sea”. 5) A ____________ covalent bond forms when electrons are shared “unfairly”. 6) A ____________ covalent bond forms when electrons are shared “fairly”. 7) Nonpolar covalent bonds always form between ________________ elements. Teacher Notes: Ionic, Covalent and Metallic Bonding Lab General Set-up to Create as a kit: This a very simple lab set up that should be created once then stored as a kit for the following year. Obtain 20 clear sample bottles with labels. Place the sample number, formula/symbol and name on each label. I use the polypropylene sample jars sold by Flinn Scientific. Sample Number Formula/Symbol Name Iron 1 Fe 2 CO2 Carbon dioxide 3 NaCl 4 Cu Sodium chloride Table salt Copper 5 C12H22O11 6 CuSO4●5H2O 7 Zn 8 MgSO4●7H2O 9 CaCO3 10 NaHCO3 11 O2 12 H2O 13 Al 14 CaCl2 15 Sn Sucrose Table sugar Copper II sulfate pentahydrate Root killer Zinc Epsom’s salt Bath salts Calcium carbonate Tum’s Sodium bicarbonate Baking soda Oxygen gas Water Aluminum foil Calcium chloride Ice melt Tin I strongly suggest that the labels contain all the information on the chart under the set up notes. This allows students to read “sucrose” then “table sugar”; again trying to consistently make connections to their everyday surroundings. This lab is very teacher friendly as it uses household materials that can quickly be placed into a sample bottle or a test tube with a screw type lid and then placed into a box for use many years to come. Teaching Tips: Students should read the background and answer all of the conclusion questions before being quietly dismissed to the lab area. This lab takes about 20 minutes to complete and could serve as an introduction or a review to bond types. It should be noted that compounds containing polyatomic ions and hydrates have both covalent and ionic bonding. This can be discussed before the students go to lab or after the students have done the lab. I use this lab as an introduction to bonding and have the following slide on the screen when they do the lab. I do not discuss that many compounds have both types of bonding until after the lab or the next day. The answer key is made according to using this lab as an introduction. If using this lab for further review then the answer key should be adjusted to show Sample bottles 6, 9, 10, 17, 19 had both ionic and covalent bonding. Ionic Starts with a metal atom ends with a nonmetal atom Covalent Starts with a nonmetal atom ends with a nonmetal atom Metallic You have a metal from the periodic table Going Further: Students could research metallic bonding and why copper is used for household wiring.