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Chemical Bonds, Names and Formulas

Chemical Bonds, Names and Formulas. Unit # 6. Big Ideas. OBJECTIVES: Distinguish between ionic and molecular compounds. Distinguish between ionic, covalent and metallic bonds Define cation and anion, and relate them to metal and nonmetal. Name molecules and compounds. What is a bond?.

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Chemical Bonds, Names and Formulas

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  1. Chemical Bonds, Names and Formulas Unit # 6

  2. Big Ideas • OBJECTIVES: • Distinguish between ionic and molecular compounds. • Distinguish between ionic, covalent and metallic bonds • Define cation and anion, and relate them to metal and nonmetal. • Name molecules and compounds

  3. What is a bond? • The valence electron of one atom is attracted to the nucleus of another atom • Reasons Why? • Mutual attraction • To achieve a full valence shell • To have lower Kinetic Energy

  4. Covalent Bonds • When a pair of electrons are “shared” between two atoms • This will occur between atoms that have similar electronegativity values • Non-metal bonded to non-metal

  5. Covalent Bonds • Single bond – one pair of electrons are shared (2 electrons) • Double bond – two pairs of electrons are shared (4 electrons) • Triple bond – three pairs of electrons are shared (6 electrons)

  6. Ionic Bonds • An unequal sharing of a pair of electrons between atoms • Between a metal and a non-metal • We usually say “ the metal will give up the electron and the non-metal will take the electron • Atoms that have a electronegativity difference higher than 1.7

  7. Metallic Bonds • Bonds between 2 metals • Both metals will give up electrons and then share the “sea of electrons”

  8. Determine the bond type • H2O • HCl • NaCl • KCr • KBr

  9. Determine the bond type • H2O covalent • HCl covalent • NaCl ionic • KCr metallic • KBr Ionic

  10. Let’s Review some old concepts to tie this together

  11. Atoms and ions • Atoms are electrically neutral. • Same number of protons and electrons. • Ions are atoms, or groups of atoms, with a charge (positive or negative) • Different numbers of protons and electrons. • Only electrons can move. • Gain or lose electrons.

  12. Anion • A negative ion. • Has gained electrons. • Nonmetals can gain electrons. • Charge is written as a superscript on the right. Has gained one electron (-ide is new ending= fluoride) F1- O2- Gained two electrons (oxide)

  13. Cations • Positive ions. • Formed by losing electrons. • More protons than electrons. • Metals can lose electrons Has lost one electron (no name change for positive ions) K1+ Ca2+ Has lost two electrons

  14. Back to New Material Now let’s bond the old material to the new material

  15. Two types of Compounds Ionic and molecular

  16. Ionic Compounds • Ionic compounds- from joining metal and nonmetal - they are electrically neutral • Metal and polyatomic ion • Ionic Bonds

  17. Ionic Compounds • This formula represents not a molecule, but a formula unit • The smallest whole number ratio of atoms in an ionic compound. • Ions surround each other so you can’t say which is hooked to which.

  18. Molecules and Molecular Compounds Molecular compounds • Made of molecules. • Made by joining nonmetal atoms together into molecules. • Covalent bonds

  19. Molecules and Molecular Compounds • Molecule- smallest electrically neutral unit, still has properties of the substance • Made from only nonmetals • Can be from one element- O2 • Can make a compound- CO2

  20. Two Types of Compounds Ionic Molecular Smallest piece Formula Unit Molecule Types of elements Metal and Nonmetal Nonmetals Solid, liquid or gas State solid Bond Type Ionic Covalent

  21. Chemical Formulas • Shows the kind and number of atoms in the smallest piece of a substance. • Molecular formula- number and kinds of atoms in a molecule. • CO2 • C6H12O6

  22. Chemical Formulas • More than one atom? –use a subscript (H2O) • There are 7 diatomic elements • Hydrogen (H2), Nitrogen (N2), Oxygen (O2), Fluorine (F2), Chlorine (Cl2), Bromine (Br2), and Iodine (I2) • Remember: “Br I N Cl H O F”

  23. Charges on ions • Elements in the same group have similar properties. • Including the charge when they are ions • Remember Group 1 forms +1 ions

  24. 1+ 2+ 3+ 3- 2- 1-

  25. What about the others? • Many transition metals have more than one common ionic charge • We use roman numerals in naming

  26. More Big ideas • OBJECTIVES: • Name ions based on their oxidation state • Define a polyatomic ion, and give the names and formulas of the most common polyatomic ions.

  27. Naming ions • Two methods if more than one charge is possible: • 1. Stock system – uses roman numerals in parenthesis to indicate the numerical value • 2. Classical method – uses root word with suffixes (-ous, -ic) • Does not give true value

  28. Naming ions • We will use the Stock system. • Cation- if the charge is always the same (Group A) just write the name of the metal. • Transition metals can have more than one type of charge. • Indicate the charge with roman numerals in parenthesis

  29. Name these • Na1+ • Ca2+ • Al3+ • Fe3+ • Fe2+ • Pb2+ • Li1+

  30. Write Formulas for these • Potassium ion • Magnesium ion • Copper (II) ion • Chromium (VI) ion • Barium ion • Mercury (II) ion

  31. Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluorine

  32. Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluorin

  33. Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluori

  34. Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluor

  35. Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluori

  36. Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluorid

  37. Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluoride

  38. Name these • Cl1- • N3- • Br1- • O2- • Ga3+

  39. Write these • Sulfide ion • iodide ion • phosphide ion • Strontium ion

  40. Exceptions: • Some of the transition metals have only one ionic charge: • Do not use roman numerals for these: • Silver is always 1+ (Ag1+) • Cadmium and Zinc are always 2+ (Cd2+ and Zn2+)

  41. Polyatomic ions • Groups of atoms that stay together and have a charge. • Acetate C2H3O21- • Nitrate NO31- • Nitrite NO21- • Hydroxide OH1- and Cyanide CN1- • Permanganate MnO41-

  42. Sulfate SO42- Sulfite SO32- Carbonate CO32- Chromate CrO42- Dichromate Cr2O72- Phosphate PO43- Phosphite PO33- Ammonium NH41+ Polyatomic ions

  43. Big Idea • OBJECTIVES: • Apply the rules for naming and writing formulas for binary ionic and ternary ionic compounds.

  44. Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • To write the names, just name the two ions. • Easy with Representative elements (which are Group A elements) • NaCl = Na1+Cl1- = sodium chloride • MgBr2 = Mg2+Br1-= magnesium bromide

  45. Naming Binary Ionic Compounds • The problem comes with the transition metals. • Need to figure out their charges. • The compound must be neutral. • same number of + and – charges. • Use the anion to determine the charge on the positive ion.

  46. Naming Binary Ionic Compounds • Write the name of CuO • Need the charge of Cu • O is 2- • copper must be 2+ • Copper (II) oxide • Name CoCl3 • Cl is 1- and there are three of them = 3- • Co must be 3+ Cobalt (III) chloride

  47. Naming Binary Ionic Compounds • Write the name of Cu2S. • Since S is 2-, the Cu2 must be 2+, so each one is 1+. • copper (I) sulfide • Fe2O3 • Each O is 2- 3 x -2 = -6 • 2 Fe must = 6+, so each is 3+. • iron (III) oxide

  48. Naming Binary Ionic Compounds • Write the names of the following • KCl • Na3N • CrN • Sc3P2 • PbO • PbO2 • Na2Se

  49. Ternary Ionic Compounds • These will have polyatomic ions • At least three elements • name the ions • NaNO3 • CaSO4 • CuSO3 • (NH4)2O

  50. Ternary Ionic Compounds • LiCN • Fe(OH)3 • (NH4)2CO3 • NiPO4

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