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Agenda Dec 3, 2019 Quick Questions(Ions Pogil - Big Ideas) Quick review Octet Rule and Ionic bonding notes Naming Ionic Compounds Pogil Start Work on Study Guide for Final 1. Write out the correct statement only. QQs a) Metals make negative anions and nonmetals make positive cations. b) Metals make positive cations and nonmetals make negative anions. c) Metals make negative cations and nonmetals make positive anions. d) Metals make positive anions and nonmetals make negative cations. 2. What is the charge on an ion with 21 protons, 25 neutrons and 18 electrons? a) 4+ b) 3+ c) 4- d) 4+ QQs 1. Write out the correct statement only. b) Metals make positive cations and nonmetals make negative anions. 2. What is the charge on an ion with 21 protons, 25 neutrons and 18 electrons? 21protons (21+) 18 electrons (18-) 21 - 18 = 3 QQs 1. Write out the correct statement only. b) Metals make positive cations and nonmetals make negative anions. 2. What is the charge on an ion with 21 protons, 25 neutrons and 18 electrons? b) 3+ 21protons (21+) 18 electrons (18-) 21 - 18 = 3 The Octet Rule Atoms tend to gain, lose or share electrons in order to acquire a full set of eight valence electrons. Electron configurations like those of the Noble gases with filled s and p orbitals of the same energy level are unusually stable. (Note that Helium has only 2 valence electrons, but that is because the 1st energy level can only accommodate 2 electrons in its 1s orbital.) Octet rule is useful for determining the type of ions that elements are likely to form. The Octet Rule in action If atoms gain or lose electrons in order to acquire a full set of eight valence electrons. When a metal with one or two valence electrons reacts with a nonmetal with 6 or 7 valence electrons we can see that both can satisfy the octet rule by reacting with each other so that 1 or 2 electrons are transferred from the metal to the nonmetal. During this reaction process metals cations (positive ions) will form and at the same time nonmetal anions (negative ions) will form - and then the oppositely charged ions will attract each other... Ionic Bonding The electrostatic (or coulombic) force that holds oppositely charged particles (cations and anions) together in an ionic compound is referred to as an ionic bond. Compounds that contain ionic bonds are referred to as ionic compounds. (When metals react with oxygen to form ionic compounds those compounds are called oxides, most other ionic compounds are called salts.) Metals - most Nonmetals of PT What kind of chemical bonding will occur from top between these 2 different types of right corner elements? Any Group 1 Halogens (or group 2 https://www.youtube.com/watch?v=d2geiGKFveE – make (Why is what he does at the end not a good idea?) metal, or any easiest transition examples metal) Na 11 p+ Cl 17 p+ 11 e- 17 e- Na• Metals from Nonmetals most of PT What kind of chemical bonding will occur from top between these 2 different types of right corner elements? Family of compounds called Any Group 1 Halogens “Salts” (or group 2 – make (see acids, bases and salts metal, or any easiest later for details) transition examples metal) Na 11 p+ Cl 17 p+ 11 e- 17 e- Na• Metals from Nonmetals most of PT What kind of chemical bonding will occur from top between these 2 different types of right corner elements? Cl 17 p+ Now (Na) 18 e- Na 11 p+ = 1- 10 e- . Cl− = 1+ + Chloride ion Na Sodium ion Simplest ratio of - + + ions is - + - - 1:1 + + - NaCl A Crystal Lattice Is a 3D arrangement of alternating positive and negative ions in all directions The electrostatic (coulombic) attraction between oppositely charged ions is ionic bonding Notes Properties of Ionic Compounds Page reference- p. 217 “No single unit consisting of only one ion attracting one other ion is formed.” Large numbers of positive ions (usually metal cations) and negative ions (often non-metal anions) exist together in a ratio determined by the number of electrons transferred from the metal to the non-metal. Properties of ionic compounds cont. Strong attraction of positive ions and negative ions result in a crystal lattice (a 3D geometric arrangement of particles, each +ve ion is surrounded by -ve ions and each -ve ion is surrounded by +ve ions). Ionic crystals will vary in shape based on the sizes and relative numbers of the ions bonded. Properties of ionic compounds cont. Physical properties: If an external force is large enough to Mpt - high Large amounts of move the ions in a crystal, the crystal energy are required to cracks as like-charged ions next to each break the ions apart; other will provide a repulsive force large Bpt - high enough to crack the crystal. Hardness - hard, rigid and brittle solids All as a result of the strong and numerous attractions between the ions in the compound. Properties of ionic compounds cont. Physical properties: Solid ionic compounds do not conduct electricity (ions cannot move). Liquid state or when dissolved in water, ionic compounds conduct electricity (ions free to move) - called electrolytes (chemical changes occur). Properties of ionic compounds cont. Lattice Energy: defined as the heat of formation for ions of opposite charge in the gas phase to combine into an ionic solid. As an example, the lattice energy of sodium chloride, NaCl, is the energy released when gaseous Na + and Cl - ions come together to form a lattice of alternating ions in the NaCl crystal. The more negative the lattice energy the stronger the force of attraction between those ions. Smaller cations tend to have more negative values for lattice energy than larger cations bonded to the same anions. Ions with larger positive or negative charge generally have more negative lattice energy. See Table 8-3 p 220 Naming Ionic Compounds Part 1 Binary Compounds Pogil Naming Ionic Compounds What are the structural units that make up ionic compounds and how are they named? Why? When working in Chemistry, it is often convenient to write a chemical in symbols. For example we might write down the substance table salt as NaCl. In talking about chemistry, however, it is a bit tacky to say “en-ay see-ell” when we want to refer to a substance. Also in formal writing we should use the name of the compound rather than its symbols. We need to learn how to say the proper names of ionic substances. Model 1 - Ion Charges for Selected Elements 1. a) Identify three elements that form only one cation. We need to learn how to say the proper names of ionic substances. Model 1 - Ion Charges for Selected Elements 1. a) Identify three elements that form only one cation. Hydrogen, Lithium, Beryllium etc. etc. We need to learn how to say the proper names of ionic substances. Model 1 - Ion Charges for Selected Elements 1. b) Identify three elements that form only one anion. Nitrogen, oxygen, fluorine (any of the ones shown). We need to learn how to say the proper names of ionic substances. Model 1 - Ion Charges for Selected Elements 1. c) Identify three elements that form more than one cation. d) In what region of the periodic table are these “multiple ion” elements usually located? We need to learn how to say the proper names of ionic substances. Model 1 - Ion Charges for Selected Elements 1. c) Identify three elements that form more then one cation. Iron, Nickel, Copper etc. d) In what region of the periodic table are these “multiple ion” elements usually located? The transition elements and low in group 14 (4A) 2. Consider K+ and S2- Write chemical formulas for all possible ionic compounds involving these ions, using the simplest ratio(s) of potassium(K) to sulfur(S). Keep in mind that the sum of the charges in an ionic compound must equal zero. 1+ (-2) = -1 how make it 0? 2. Consider K+ and S2- Write chemical formulas for all possible ionic compounds involving these ions, using the simplest ratio(s) of potassium(K) to sulfur(S). Keep in mind that the sum of the charges in an ionic compound must equal zero. 1+ (-2) = -1 how make it 0? 2(1+) - 2 = 0 Need 2 K+ to every 1 S2- 2. Consider K+ and S2- K2S We use the charges on the ions to figure out what the formula will be, but we don’t show that information when we write a formula. Only this one ratio makes an electrically neutral compound. 2. Consider Fe2+ or Fe3+ and S2- For 2+ ion 2+ (-2) = 0 2+ - 2 = 0 1:1 Ratio Formula: FeS 2. Consider Fe2+ or Fe3+ and S2- For 2+ ion For 3+ ion 2+ (-2) = 0 3+ - 2 = +1 1:1 Ratio Common multiples? Formula: FeS 2. Consider Fe2+ or Fe3+ and S2- For 2+ ion For 3+ ion 2+ (-2) = 0 3+ - 2 = +1 1:1 Ratio lowest common multiple? 2(3+) + 3(-2) = 0 Formula: FeS 2. Consider Fe2+ or Fe3+ and S2- For 2+ ion For 3+ ion 2+ (-2) = 0 3+ - 2 = +1 1:1 Ratio LCM? 2(3+) + 3(-2) = 0 Ratio Fe:S is 2:3 Formula: FeS 2. Consider Fe2+ or Fe3+ and S2- For 2+ ion For 3+ ion 2+ (-2) = 0 3+ - 2 = +1 1:1 Ratio LCM? 2(3+) + 3(-2) = 0 Ratio Fe:S is 2:3 Formula: FeS Fe2S3 Model 2 - Ionic Compound Names (Metals that form one ion ONLY) 4.
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