Chemistry – Nov 28, 2016 P3 Challenge- Today’s Objective – Identify the ion formed by each of the following elements: 1) Potassium, K 2) Chlorine, Cl 3) Zinc, Zn Today’s Objective – Ionic Compounds (Get out your colored periodic table)

Chemistry – Nov 28, 2016 Objective – Ionic compound identification Ionic compound formation Ionic compound nomenclature Assignment: Ionic Compounds Worksheet Agenda Valence electrons Identifying types of compounds Writing ionic formulas Type I Ionic Nomenclature Type II Ionic Nomenclature Polyatomic ions

Valence Electrons The outermost electrons of an atom will be located in the s and p orbitals with the highest principle quantum number. These are the valence electrons. All other electrons are core electrons. Because the s subshell can carry 2 electrons and the p subshell can carry 6 electrons, the maximum number of valence electrons is 8, an octet. A completed octet of valence electrons is the most stable configuration for an atom and explains why atoms form the ions that they do.

Compound formation – two methods Ionic compounds form between metal and nonmetal elements by transferring electrons Cation (metal ion) and anion (nonmetal ion) Both cation and anions achieve completed octets Two metal elements do not form compounds Two nonmetal elements can form molecular compounds by sharing electrons Both nonmetals get surrounded by 8 electrons

Chemical Formulas Chemical Formula tells number and types of elements Ionic – formula unit; a representative sample of elements in lattice Molecular – formula shows number and type of atoms in one molecule

Writing Formulas Because compounds are electrically neutral, one can determine the formula of a compound this way: The charge on the cation becomes the subscript on the anion. The charge on the anion becomes the subscript on the cation. If these subscripts are not in the lowest whole-number ratio, divide them by the greatest common factor. “Switch, Drop and Reduce”

Writing Formulas of Ionic Compounds Predict ionic compounds that form using the exponent switch and reduce process to create a neutral formula. Formula always written with cation (metal) first Ex: compound formed by barium and chlorine Ex: compound formed by aluminum and oxygen Ex: compound formed by sulfur and sodium Ex: compound formed by Fe+2 and oxygen

Polyatomic Ions and compounds Often two or more atoms form a group that has a collective charge. Memorize the polyatomic ions (see next slide). Make flash cards. Seriously. NEVER change the formula of a polyatomic ion Imagine a shrink-wrap packaging goes around the number and types of atoms and you cannot break up this bundle Polyatomic ions form ionic compounds. Ex: sodium and carbonate Na+ and CO3-2 Na2CO3 Ex: calcium and nitrite Use parentheses: Ca2+ and NO2- Ca(NO2)2

Three types of ionic compounds Type 1 - Binary compound (contains only two elements) and cation charge is known because atom can form only one type of ion. Metal forms only one type of ion: Groups 1A, 2A, Al3+, Ga3+, Zn2+, Cd2+, and Ag+ Type 2 – Binary compound with variable charge cations. Transition metals and representative metals. Type 3 – Polyatomic ion compound contains three or more elements contained within one or two polyatomic ions.

Type 1 Ionic Compounds Formed by electron transfer from a metal to a nonmetal Metal forms only one type of ion: Groups 1A, 2A, Al3+, Ga3+, Zn2+, Cd2+, and Ag+ Name as metal nonmetalide Name Formula sodium chloride KBr calcium oxide Al2O3 lithium fluoride ZnI2 beryllium nitride Ag2S

Type 2 Ionic compounds – Transition Metals Most transition metals and group 13-16 metals form multiple ions. Cr, Fe and Co form 2+ and 3+ ions Cu forms 1+ and 2+ ions Sn, Pb form 2+ and 4+ ions Mercury (II) is Hg2+, while Mercury (I) is Hg22+ Named as metal (roman numeral for charge on metal) nonmetalide Name Formula lead (II) oxide CuO tin (IV) fluride Hg2S copper (I) bromide CoP iron (III) selenide Cr3N2

Type 3 Ionic compounds – polyatomic ions Formula will have more than two elements Often includes oxygen Often includes () around a polyatomic ion Name as cation anion Name Formula sodium carbonate CuOH tin (II) cyanide Mg(ClO2)2 ammonium nitrate FePO4 barium sulfate LiN02

Exit Slip - Homework Exit Slip: Name Ca(OH)2 Write the formula for Iron (II) sulfate What’s Due? (Pending assignments to complete.) Ionic Compounds Worksheet What’s Next? (How to prepare for the next day) Read Holt p159-175