Note for CH 104 with Professor Woski at UA-Study Guide Exam 2
Note for CH 104 with Professor Woski at UA-Study Guide Exam 2
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This 4 page Study Guide was uploaded by an elite notetaker on Friday February 6, 2015. The Study Guide belongs to a course at University of Alabama - Tuscaloosa taught by a professor in Fall. Since its upload, it has received 16 views.
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Date Created: 02/06/15
Exam 2 Outline CH 104 F all 2009 You need to bring a pencil a calculator and your ACT card ALL 0th er materials must be left at th e front of the classroom in an unsecured area ALL cellphones must be turned off during exam Chapter 4 Ionic Compounds 1 2 Use the octet rule to determine the ionic charge of ions for representative elements Sections 41 amp 42 Octet rule atoms will gain lose or share valence electrons to reach an octet or duet in the case of hydrogen Atoms and molecules that lose electrons become positively charged cations Atoms and molecules that gain electrons become negatively charged anions Exceptions to octet rule 0 Hydrogen only needs duet 2 o Boron and aluminum usually only has 6 Use charge balance to write an ionic formula Sections 4348 Ionic compounds consist of a cation a metal or ammonium ion and an anion nonmetal or polyatomic ion Ionic compounds are neutral therefore positive charges balance out negative charges Some ions have typical charges Group 1 alkali metals 1 Group 2 alkaline earth metals 2 Group 3A aluminum 3 Group SA N P 3 Group 6A 0 S 2 Group 7A halogens 1 o Polyatomic ions Table 43 Transition metals can typically have more than one possible charge indicated in the usual way for example Fe or by roman numeral after element symbol or name FeIII and iron 111 Be able to name ionic compounds cation first then anion Sections 47410 especially Tables 4143 000000 3 Acids and Bases Section 411 Acids provide H ions in water Bases provide OH ions in water Know names and formulas of common acids Table 45 Chapter 5 Covalent Compounds 1 Draw the electron dot structure for covalent compounds Sections 5155 0 Each valence electron is represented as a dot Section 55 o Paired electrons are represented as a pair of dots lone pair or a line shared or bonding pair 0 Covalent bond is pair of electrons shared to give both atoms an octet electrons count for both atoms Section 51 0 To draw 0 Must be given connectivity of atoms Count total number of valence electrons Form single bonds between atoms Put remaining electrons in lone pairs to nish off octets If unable to give each atom an octet use lone pair on neighboring atom to form double or triple bonds 0 O O O 2 Shapes of molecules Section 57 0 Count groups of electrons around the atom of interest lone pairs and bonds single double or triple number determines geometry of the electron groups 0 2 groups linear o 3 groups trigonal planar o 4 groups tetrahedral 0 Geometry of atoms alone not lone pairs determine the shape of a molecule 0 For example tetrahedral arrangement of electrons in water H20 and ammonia NH3 result in bent and pyramidal geometries of the molecules 3 Use electronegativity values to identify polar and nonpolar covalent bonds Sections 5859 o Electronegativity describes the tendency of an atom to hang on to the electrons in a bond 0 Values increase from left to right across the periodic table for example Li 10 Be 15 B 20 C 25 N 30 O 35 F 40 0 Values decrease going from top to bottom of a group for example F gt C1 gt Br gt I o The difference in electronegativity between two bonded nonmetal atoms determines the type of bond 0 0 N 04 nonpolar covalent o 04 N 19 polar covalent o 220 ionic o Polarity of bonds results in more negative charge accumulating on the more electronegative atom and more positive charge on the less electronegative atom 4 Write the correct names for covalent compounds Section 510 o For covalent compounds pre xes indicate multiple atoms 0 Mono 1 not usually used 0 Di 2 o Tri 3 o Tetra 4 o Penta 5 o Hexa 6 o Diatomic elements H2 N2 02 F2 C12 Br2 I2 and polyatomic elements P4 S8 are usually named for the element without a pre x Chapter 6 Chemical Reactions 1 Write a balanced equation for a reaction when given the reactants and products Sections 61 amp 62 o balanced equation has an equal number of atoms of each element on both the reactant and product sides 0 write equation with correct formulas 0 determine is equation is already balanced 0 balance equation one element at a time Be careful balancing one element may cause another previously balanced element to become unbalanced 2 Moles Section 63 o Avogadro s number of anything atoms molecules ions bananas is a mole o Avogadro s number 602 X 1023 o Subscript in a molecular formula indicates the number of atoms of an element in that molecule and the number of moles of the element in a mole of the molecule 3 Determine the molar mass of a compound from its formula Section 63 o The molar mass of an element in grams atomic mass of an element in amu 0 Based on 12C 1 mole 120 g o Molar mass of a molecule is the sum of the molar masses of its constituent elements multiplied by their subscripts 4 Use the molar mass to convert between the grams of a substance and the number of moles Section 54 o Grams molar mass X number of moles 0 Number of moles grams molar mass 5 Using a given number of moles of a starting material determine the corresponding number of moles ofa product and visa versa Section 65 o Coefficients in balanced equations shows relative numbers of moles of each substance in the reaction o Ratios of the coefficients can be used to calculate number of moles of all compounds in the reaction from any one 6 Using a given number of grams of a starting material determine the corresponding mass of a product and visa versa Section 66 o Grams of any component can be converted into the number of moles o Moles can be converted back into grams 7 Determine the limiting reactant and calculate the amount of product formed Section 67 o In some reaction mixtures an excess of one or more reactants may be present 0 Amount of product depends on the amount of limiting reagent 0 Limiting reagent forms smallest amount of products 0 Watch coef cients 0 Given the actual yield of a product calculate the percent yield 0 Theoretical yield maximum yield of product based on limiting reagent 0 Percent yield actual yield theoretical yield X 100 8 Classes of Chemical Reactions Sections 68 o Precipitation reactions Section 69 0 Know solubility guidelines in Table 61 o Halides with Ag ngz and Pb2 are generally insoluble o Sulfates with Ba Hg22 and Pb2 are also generally insoluble o Acidbase neutralization reactions Section 610 0 Acid base salt water 0 Oxidationreduction reaction Section 6 l l 0 Be able to identify which species is being oxidized and which is being reduced 0 Any reaction where an atom changes charge is an oxidationreduction I For example ironIII gt ironH I Note pure elements monoatomic for example Fe diatomic for example N2 and polyatomic for example S8 have a charge of zero 0 Loss of electrons is oxidation LEO for example Fe2 gt Fe 0 Gain in electrons is reduction GER for example Brz gt 2Br o LEO the lion says GER
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