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Chemical Bonding

Chemical Bonding. Chapter 17. Chapter 17. Ions and Molecules. Ions. What is an ion?. An atom that has either gained or lost one or more electrons Positive ion – cation Negative ion – anion Electrons have a charge of -1 (be careful when you add or subtract). Sodium Ion.

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Chemical Bonding

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  1. Chemical Bonding Chapter 17

  2. Chapter 17 Ions and Molecules

  3. Ions • What is an ion? • An atom that has either gained or lost one or more electrons • Positive ion – cation • Negative ion – anion • Electrons have a charge of -1 (be careful when you add or subtract)

  4. Sodium Ion • How many protons and electrons does sodium have? • What is the best way to make sodium stable? • 11 protons • 11 electrons • Lose 1 electron • Na1+

  5. Chlorine Ion • How many protons and electrons does chlorine have? • What is the best way to make chlorine stable? • 17 protons • 17 electrons • Gain 1 electron • Cl1-

  6. Ions • How do we determine charge? • Determine the number of electrons that should exist in the neutral atom (atomic number) • Determine how many electrons are present • Subtract and assign the charge, this is called the oxidation state NOTE: An element may have more than one oxidation state

  7. Most Common Oxidation States

  8. Ions • Determine how many electrons there are in the following ions: • Mg2+ • Fe3+ • C4- • I7- • Ar0 • lost 2 & has 10 electrons • lost 3 & has 23 electrons • gained 4 & has10 electrons • gained 7 & has 60 electrons • gained/lost none & has 18 electrons

  9. Molecules • What is the difference between monatomic, diatomic and polyatomic? • Monatomic – only one atom • Metals and noble gases are monatomic atoms • Diatomic – contains two atoms • Ex. H2 or CO • Polyatomic - contains more than two atoms • Ex. H2O and O3

  10. Molecules • What are molecules? • Any diatomic or polyatomic combination of atoms • A molecule can be an element or a compound • Cl2 vs. O3 vs. H2O Element Element Compound

  11. Molecules and Ions • What is the connection between molecules and ions? • An ion is a charged atom • A polyatomic ion is a charged diatomic or polyatomic molecule • OH1- (hydroxide) • CN1- (cyanide) • CO32- (carbonate) • NH41+ (ammonium)

  12. Chapter 17 Chemical Formulas

  13. Chemical Formulas • What is a chemical formula? • Shows us what elements the are in the molecule • How many atoms of each element are present

  14. Chemical Formulas • What is the formula for three caffeine molecules? • 3C8H10N4O2 • Subscript indicates how many of each element are in the molecule • 8 carbons • 10 hydrogens • 4 nitrogens • 2 oxygens • Coefficient shows how many molecules

  15. Chemical Formulas • How do sodium and chlorine combine? • Oppositely charged ions attract each other • Na1+ and Cl1- chemically combine to create the compound NaCl, which is table salt

  16. Chemical Formulas • How do we make a chemical formula neutral? • The total charge of the ions in the molecule equals zero • Must have positive and negative ions to do this • If the charges don’t cancel out use subscripts to balance them

  17. Chemical Formulas • How do you determine a chemical formula? • Use the “swap and drop” method • Ex. Iron (III) Sulfide NOTE! If the positive and negative charge are the same, the subscripts NEED to be set to 1

  18. Chemical Formulas • What is the formula for magnesium bromide? • Mg2+ and Br1- • “swap and drop” • Mg1Br2, but we do not write the 1 • MgBr2

  19. Chemical Formulas • What happens when we have a polyatomic ion? • What is the formula for potassium cyanide (CN1-)? • Treat the polyatomic as one piece with one charge • K1+ and CN1- • “swap and drop” • KCN

  20. Chemical Formulas Practice • What are the formulas of the following chemicals: • Lithium and Bromide • Aluminum and Chloride • Beryllium and Oxide • Sodium and Hydroxide • Calcium and Nitrate • LiBr • AlCl3 • BeO • NaOH • Ca(NO3)2 Same charges, so subscripts changed to 1 Need parentheses to show that it is one piece

  21. Ion Puzzle Cards • Please combine the following ion puzzle pieces and write the chemical formula in your notes: • Barium and Chloride • Potassium and Bromide • Cesium and Fluoride • Silver and Chloride • Scandium and Nitride • Barium and Hydroxide

  22. Ion Puzzle Cards Continued • Aluminum and Hydroxide • Zinc and Chloride • Barium and Sulfide • Potassium and Cyanide • Ammoniumand Chloride • Lead andChloride • Zincand Carbonate • Sodium andOxide • Lead and Sulfide (Careful with this one!)

  23. Chapter 17 Naming Compounds

  24. Chemical Formulas Undone • How do you determine the oxidation states from the formula? • Al2O3 • FeCl3 • KOH • Reverse the “swap and drop” method • Remember: The cation always comes before the anion! • Al 3+ and O2- • Fe3+ and Cl1- • K1+ and OH1- One piece with one charge!

  25. Naming Compounds • What scientific word do we use for naming? • What is the difference between organic and inorganic compounds? • Nomenclature • Organic compounds contain primarily carbon and hydrogen and inorganic compounds don’t

  26. Naming Compounds • What two main categories can we divide inorganic compounds into? • Covalent compounds are made up of only non-metals or metalloids • Metalloids are B, Si, Ge, As, Sb, Te and Po • Ionic compounds are made up of metals and non-metals

  27. Naming Ionic Compounds • How do you name an ionic compound? • Step 1: Write the name of the cation first • Step 2: Write the name of the anion but change the suffix (ending) to –ide • NaCl • Ex. Sodium Chloride • NOTE: If there is a polyatomic ion, its name does not change

  28. Naming Ionic Compounds • How do you name an ionic compound that has more than one oxidation state? • Using roman numerals to represent the oxidation state • Ex. Iron • Iron(II) or Fe(II) • Iron(III) or Fe (III) • Ex. Fe2O3 • Iron (III) Oxide

  29. Naming Ionic CompoundsPractice • Please name the following ionic compounds: • AlCl3 • NaOH • AgO • MoI6 • Y2Te3 • NbF5 • IrI • Cr2O3 • HgCl • Pb(NO3)4 • Aluminum Chloride • Sodium Hydroxide • Silver Oxide • Molybdenum Iodide • Yttrium Telluride • Niobium (V) fluoride • Iridium Iodide • Chromium (III) oxide • Mercury (I) chloride • Lead (IV) nitrate

  30. Naming compounds • How do you name covalent compounds? • Step 1: Write the name of the first part without any suffix • If there is more than one, add the appropriate prefix • Step 2: Write the name of the second part change the suffix (ending) to –ideand add the appropriate prefix • CO2 • Ex. Carbon Dioxide

  31. Naming Covalent CompoundsPractice • Please name the following covalent compounds: • SO2 • BF3 • SiO4 • C2S4 • NF3 • PoBr2 • SeI4 • NO2 • CO • Sulfur dioxide • Boron trifluoride • Silicon tetroxide • Dicarbontetrasulfide • Nitrogen trifluoride • Polonium dibromide • Selenium tetraiodide • Nitrogen dioxide • Carbon monoxide

  32. Chapter 17 Metallic Bonding

  33. Chemical Bonds • What is a chemical bond? • A force that holds two or more elements together • Three types: • Metallic • Ionic • Covalent

  34. Metallic Bonds • What do metals do with their valence electrons? • Lose/donate them and become cations (positively charged) to become stable

  35. Metallic Bonds • How do the metal ions arrange themselves? • Arranged in perfect rows and columns • In a crystal structure, called a lattice

  36. Metallic Bonds • Where are the electrons that were lost/donated? • Moving through the lattice around the metal ions • “Sea of Electrons” • These electrons hold the ions together in a metallic bond

  37. Metallic Bonds • What are metallic bonds responsible for? • Metals can: • Conduct electricity and heat because electrons are easily moved • Be easily bent and shaped because of the lattice structure • Malleable – bendable • Ductile – drawn into a wire

  38. Metallic Bonds • What is an alloy? • A homogeneous mixture of two or more metals held together by metallic bonds • Two parts: • Base metal • Solute (metal that’s added) • Examples: • Brass (Cu Zn) • Stainless Steel (Fe Ni Cr) • White Gold (Au Ni)

  39. Metallic Bonds • What is 24kt gold? • Pure gold ions • Anything less than 24kt will contain a mixture of other metal ions like silver and copper making it an alloy

  40. Metallic Bonds • Why would we want to build alloys? • Alloys allow us to change the properties of metals like… • Hardness • Strength • Melting point • Ex. Adding other metals to gold makes it harder and more durable

  41. What is an Alloy? - Video

  42. Nitinol Alloy – Memory Metal Video

  43. Chapter 17 Ionic Bonding

  44. Lewis Dot Digrams (Review) • Responsible for how an element reacts • Shows the element symbol with only the number of valence electrons (as dots) • NOTE: Remember how we placed them before • Ex. Chlorine • Why are valence electrons important? • How do dot structures emphasize this?

  45. Lewis Dot Diagram Practice • What are the dot diagrams for C, N, Mg and S?

  46. Ionic Bond • An electrostatic force that holds ions together in an ionic compound • In other words, opposite charges attract and like charges repel • What is an ionic bond?

  47. Ionic Bond • Metals are always cations (+) • Nonmetals can be anions (-) • A metal-nonmetal bond is called an ionic bond • Ex. NaCl • How does periodic position determine whether a bond will be ionic?

  48. Ionic Bond • Are the following bonds ionic, yes or no? • Ca-Br • Be-Br • Si-F • K-Cl • O-H • Yes (metal-nonmetal) • Yes (metal-nonmetal) • No (metalloid-nonmetal) • Yes (metal-nonmetal) • No (nonmetal-nonmetal)

  49. Ionic Bond • How is an ionic bond formed? • Electrons are transferred which create ions • Positive and negative ions attract each other • Ionic bond created

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