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BELL RINGER: Write the charges for the following elements/polyatomic ions
Mg Li P K Ba I Cl O S Nitrate Sulfate Acetate Chromate Carbonate Cyanide
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Ionic compounds
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What is a bond? A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds them together. Can be formed by atoms gaining, losing, or sharing electrons. Why do atoms form chemical bonds? To become more stable (lower potential energy) ONLY valence electrons are used for bonding.
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Ionic bonds Atoms lose or gain electrons to satisfy octet (become more stable) Form two kinds of ions—atom that has an electrical charge. Cations—positively charged atoms. Anions—negatively charged atoms
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Periodic trends associated with ionic bonding
Ionization energy—energy required to remove an electron from the outer shell of an atom. Electron affinity—the change in energy when an electron is added to the outer shell. For bonding—High IE, high EA = less likely to give electrons = anion Low IE, low EA = more likely to give electrons = cation Need more convincing? Draw orbital diagram for F.
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Formation of Cations Atoms that lose electrons: Examples: Metals
Low IE—does not require a ton of energy to take an e- away Low EA-does not readily accept other e- into outer shell. Examples: Metals Li, Na, K, Be, Mg, Ca, etc Draw orbital diagrams for the following: Li
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Transition Metals Form cations with different oxidation states (depends on what it’s bound to) Titanium: [Ar]4s23d2 Can lose two electrons for Ti2+ or four electrons for Ti4+ Sometimes they will rearrange to have a pseudo-noble gas configuration (full outer shell, but not really) Copper usually has its electrons fully rearrange to form [Cu]4s13d10 instead of [Cu]4s23d9
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Formation of Anions Atoms that gain electrons:
High IE—requires a ton of energy to take an e- away High EA-readily accepts other e- into outer shell. Examples: Halogens and nonmetals F, N, O, Cl, etc. Draw orbital diagrams of the valence shells of the following: S
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EXIT SLIP - Write the oxidation states for the following elements
B Br N Be Na F Al Se As
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Ionic Bonds Held together by electrostatic force
Electrostatic force—force of attraction between positively and negatively charged particles
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Crystal lattice What is it?
a 3 dimensional geometric arrangement of particles where + and – ions surround each other the ions are packed into a regular repeating pattern that balances the forces of attraction and repulsion between the atoms
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Crystal lattice Na Cl - In a solid state, ionic compounds are non-conductors, ions must be free to move for a current to pass through it - In a liquid state (molten) or when dissolved in water they are good conductors (ions are free to move)
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Amorphous—particles are arranged randomly throughout the solid
Crystalline—particles pack in an organized fashion Amorphous Crystalline
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Amorphous Crystalline
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Lattice energy The energy released when 1 mol of an ionic compound is formed from gaseous ions. Endothermic—energy has to be absorbed for the rxn to happen Surroundings are colder Exothermic—energy is released (Ex: -436 kJ/mol) Surroundings feel warmer since energy is given off Which is more stable?
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Formation of ionic compounds is almost ALWAYS exothermic Why
Formation of ionic compounds is almost ALWAYS exothermic Why??? More stable with lower potential energy
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Formulas Formula unit--represents the most simple ratio of the ions in an ionic compound The total number of e-‘s gained by the nonmetal must equal the number lost by the metal atoms Oxidation states—give insight into how the atom will bond Used to determine the formula for a compound
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Nomenclature What is it?? Rules for ionic nomenclature
The naming and writing of formulas for chemical compounds. Rules for ionic nomenclature 1.) Cation is ALWAYS written first. 2.) Anion is ALWAYS written second. 3.) Use subscripts to cancel out charges 4.) Overall charge of the compound formed is always ZERO
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Write the formulas for a compound formed by the following elements.
Practice Write the formulas for a compound formed by the following elements. K and Cl Mg and Br Li and O
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Rules for ionic nomenclature
Write the name of the cation 1st using the elements name Write the root word of the anion 2nd plus change the suffix to “ide” NEVER change the name of a polyatomic ion Transition metals can have more than one ox. # Write the elemental name then give ox. # as roman numeral in parenthesis. Ex: iron (III) oxide
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Write the name of the following compounds:
Practice Write the name of the following compounds: MgCl2 CaCO3 Cu2(SO4)3 KCN AgOH TiS2
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Write the formulas for the following compounds:
Practice Write the formulas for the following compounds: Magnesium Bromide Sodium Nitrate Calcium Carbonate Palladium (II) Chloride
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Nomenclature Practice
Elements Bonding Chemical Formula Chemical Name Mg + NO3 Al + Br Ag2+ + CrO4 C2H3O2 + Ca F + NH4 Be + IO3 SO4 + NH4 Li + AsO4 Fe2+ + PO4 Cu2+ + P K + Cr2O7 Ba + N Nomenclature Practice
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Hydrides Hydrogen can gain or lose one e- depending on what it binds with… WHY? When bonding with metals, H gains an e- Since it is an anion, it gets the “-ide” suffix Examples: LiH, MgH2, NaH, etc.
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Hydrates Contain water in crystalline lattice
Can remove water without chemically altering substance Nomenclature is the same as ionic compounds, except take water molecules into account. How? Use prefixes to show number of water molecules
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Nomenclature for Hydrates
Examples: CuSO4· 5H2O 1.) Use name of compound: Copper (II) Sulfate. 2.) Name hydrate with correct prefix: Hexa = 6 Mono = 1 Hepta = 7 Di = 2 Octa = 8 Tri = 3 Nona = 9 Tetra = 4 Deca = 10 Penta = 5
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Practice Name the following compounds: NaCl∙2H2O MgSO4∙7H2O Al2(SO4)3∙9H2O CoCl2∙5H2O NiCl4∙3H2O
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Practice Write the names for the following compounds:
Iron (II) fluoride tetrahydrate Barium hydroxide octahydrate Lead (II) perchlorate pentahydrate Copper (II) acetate monohydrate Tin (II) chloride dihydrate
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