First Sci-Fi Movie Released (1902) Read for Thursday Read for Thursday Chapter 3: Sections 3-4 Chapter 3: Sections 3-4 HOMEWORK – DUE Thursday 9/3/15 HOMEWORK – DUE Thursday 9/3/15 HW-BW 2 (Homework Bookwork) #’s 1-7 all, 14, 19, 21, 23, 36, all, 57, all, 81, 82, 113, 114, 116, 127, 132 HW-BW 2 (Homework Bookwork) #’s 1-7 all, 14, 19, 21, 23, 36, all, 57, all, 81, 82, 113, 114, 116, 127, 132 HW-WS 2 (Homework Worksheet) (from course website) HW-WS 2 (Homework Worksheet) (from course website) HOMEWORK – DUE Tuesday 9/8/15 HOMEWORK – DUE Tuesday 9/8/15 HW-BW 3.1 (Bookwork) CH 3 #’s 3, 4, all, 26, 27 HW-BW 3.1 (Bookwork) CH 3 #’s 3, 4, all, 26, 27 HW-WS 3 (Worksheet) (from course website) HW-WS 3 (Worksheet) (from course website) HOMEWORK – DUE Thursday 9/10/15 HOMEWORK – DUE Thursday 9/10/15 HW-BW 3.2 (Bookwork) CH 3 #’s 41, 45, 48, all, 68, 70, 72, 73, 78, 79, 85, 88, 95, 96, 104, 119, 124 HW-BW 3.2 (Bookwork) CH 3 #’s 41, 45, 48, all, 68, 70, 72, 73, 78, 79, 85, 88, 95, 96, 104, 119, 124 HW-WS 4 (Worksheet) (from course website) HW-WS 4 (Worksheet) (from course website) Lab Wednesday/Thursday Lab Wednesday/Thursday EXP #2- PRELAB!!!! EXP #2- PRELAB!!!!

Atoms vs. Ions Atoms can gain or lose e - to form IONS Atoms can gain or lose e - to form IONS ANY charged particle is called an ANY charged particle is called an ion Losing e - gives charge Losing e - gives POSITIVELY charge Called Called cations Usually formed from metals Usually formed from metals Gaining e - gives a charged ion Gaining e - gives a NEGATIVELY charged ion

16 e - = Charge!!! When an atom GAINS electrons S S  S 2- S  S e- BeforeAfter S S + 2e -  S + 2e -  S 2- WRONG!! 18 e - = 18 e – 16 p + = 16 p + – –2

Atoms vs. Ions Atoms can gain or lose e - to form IONS Atoms can gain or lose e - to form IONS ANY charged particle is called an ANY charged particle is called an ion Losing e - gives charge Losing e - gives POSITIVELY charge Called Called cations Usually formed from metals Usually formed from metals Gaining e - gives a charged ion Gaining e - gives a NEGATIVELY charged ion Called Called anions Usually formed from non-metals Usually formed from non-metals

My Atom Broke Subatomic Particles Subatomic Particles Nucleus Nucleus Neutrons – n o Neutrons – n o No charge No charge # can vary from atom to atom # can vary from atom to atom

Mass of n o about equal to mass of p + Do each of these atoms have the same mass? Isotopes: Atoms having the same atomic number, but different atomic masses

Atomic symbols E A Z Symbol of element Atomic number Mass number= # p + + # n o S 16

32 16 A Z S E S S S S Shorthand: Sulfur-33 S S

Give the atom notation for the following: 1) an atom with 82 p + and 126 n o 2) an atom of iron with 28 n o and 26 e - 3) an atom of element 29 having 34 n o and 27 e Pb Fe Cu 82 p n o = +2

Information from the Periodic Table = amu (atomic mass) = amu (atomic mass) (atomic number) 20 = (atomic number) 8 =

Atomic Masses Measured in the unit amu Stands for atomic mass unit Defined as 1/12 th the mass of a 12 C atom 35 Cl = amu 50 V = amu 79 Br = amu Are these what the P.T. say?

All Isotopes are NOT Created Equal Weighted averages Weighted averages

All Isotopes are NOT Created Equal Atomic mass is a WEIGHTED average of isotopes HUH?? FinalQuiz Possible You earned 2855 average = (93.75%)(6.25%) (score 1 x weight 1 ) + (score 2 x weight 2 ) = grade (285 (285 x ) (285 x ) + (5 (285 x ) + (5 x ) = (285 x ) + (5 x ) = 267.5

All Isotopes are NOT Created Equal Weighted averages Weighted averages An equation (oh crap) An equation (oh crap) 35 Cl = amu 35 Cl = amu Abundance = 75.77% Abundance = 75.77% 37 Cl = amu 37 Cl = amu Abundance = 24.23% Abundance = 24.23% These must be the only 2 isotopes... Why? These must be the only 2 isotopes... Why?

35 Cl = amu Abundance = 75.77% 37 Cl = amu Abundance = 24.23% x x = 35.45amu Where have I seen this before? Periodic Table gives AVERAGE ATOMIC MASS in amu!! = = All Isotopes are NOT Created Equal

78.90% of all magnesium is 24 Mg  amu 10.00% of all magnesium is 25 Mg  amu 11.10% of all magnesium is 26 Mg  amu 11.10% % = amu A Problem! What is the average atomic mass of magnesium?

Some Algebra and a New Equation decimal, not % (i.e not 12.34%) For solving for % abundance multiply by 100 to get percentages

DO NOT use “normal” averages DO NOT use “normal” averages If asked for two percent-abundances, use: If asked for two percent-abundances, use: If asked for ANYTHING else: If asked for ANYTHING else: Isotopes Calculation Summary

Another Problem! Lead has 4 isotopes, the masses and abundances of which can be found in the following table. Your job? Calculate the isotope mass of lead-207. lead amu 1.40% lead amu 24.10% lead-207???? lead amu 52.40% ???? 22.10% X = Lead-207 = amu

A Problem! Thallium has 2 isotopes, and. has a mass of amu and has a mass of amu. What are the percent abundances of each of the isotopes?  Abundance 1 = 30.2%  Abundance 2 = 69.8%

A Problem! Bromine has 2 isotopes, and. has a mass of amu and has a mass of amu. What are the percent abundances of each of the isotopes?  Abundance 1 = 50.44%  Abundance 2 = 49.56%

Percent Composition How much of each element makes up a compound