ETH Zurich Chemistry Lecture 1 PDF Fall 2024

Summary

This is a chemistry lecture document for a course at ETH Zurich. It covers various topics, including introductory chemistry, syllabus, teaching assistants, and the required textbook. The lecture notes are from Fall 2024.

Full Transcript

Lecture #1, p. 1 Chemistry Fall 2024 Lecturer: Prof. David J. Norris Email: [email protected] Office: LEE...

Lecture #1, p. 1 Chemistry Fall 2024 Lecturer: Prof. David J. Norris Email: [email protected] Office: LEE P210 Office hours: Thursdays 17:00–18:00 or by appointment Chemistry Unfortunately myAmericanEnglish fromChicago stuckwith Problems Letmeknow Also I amold school I liketousechalkboardtoslowmedown But I willuseslidesalso especiallyearlyincourse Lecture #1, p. 2 Teaching Assistants Chemistry Lecture #1, p. 3 Syllabus Website: All course information will be on Moodle https://moodle-app2.let.ethz.ch/course/view.php?id=22903 Text: Chemistry: The Central Science in SI Units, 15th Edition, ©2022 By Theodore E. Brown, et al. Exercises: Fridays, 14:00–16:00 Review lectures, work problems Important! Problem Sets: Weekly, collected Three weeks graded at random PS #1 Pass 2 out of 3? Get bonus: 0.25 point on final grade Posted on Moodle Due Friday Sept. 27, 14:00 Chemistry Lecture #1, p. 4 www.eth-store.ch Required Book Title: Chemistry: The Central Science in SI Units, Global Edition Authors: Theodore Brown, H. LeMay, Bruce Bursten, Catherine Murphy, Patrick Woodward ISBN: Available in ETH Store 978-1-292-40761-6 Orell Füssli Campus Polyterrasse Mo – Fr, 10:00 – 16:00 Or online at www.orellfuessli.ch Price CHF 88.90 Lecture #1, p. 5 Why Chemistry? (For mechanical and process engineers?) ETH engineers must know basic chemistry as part of their education MAVT graduates now do everything! Need chemistry knowledge so you are not left behind! MAVT students were previously told to ignore chemistry Later regretted their poor chemistry knowledge World Needs You! Examples: Face critical crises SAF? Need world-class engineers Hydrogen-fired turbines? Batteries? Your generation must save world Carbon capture? Transportation? Biomedical devices? Chemistry Martgraduatesdoeverythingfrom soft tiestobiomedicaltocombustion Lecture #1, p. 6 Why Chemistry? (For mechanical and process engineers?) ETH engineers must know basic chemistry as part of their education MAVT graduates now do everything! Need chemistry knowledge so you are not left behind! MAVT students were previously told to ignore chemistry Later regretted their poor chemistry knowledge Goals? My Challenge? This is introductory chemistry course Your broad knowledge My goal: to teach you basic chemistry Try to keep everyone engaged Your goal: to learn basic chemistry Even “experts” continue to learn Some tutorials in early exercises Chemistry Lecture #1, p. 7 Your Challenge? 71,222 peo Been to a “live” concert? ple Why? Collective experience! Similarly for lectures Your job: ask questions Stay engaged Do Well Apologies in Advance... Final exam now in January My handwriting Save good grade for Basisprüfung German translations Feedback always welcome Questions? Chemistry Askquestions I lovequestions If something is unclearforyouothersarealsoconfused Let'sstopandclarifytogether Lecture #1, p. 8 Lecture 1 Brown 1.1 The Study of Chemistry 1.2 Classification of Matter 1.3 Properties of Matter 2.1 The Atomic Theory of Matter 2.3 The Modern View of Atomic Structure 2.4 Atomic Weights 2.5 The Periodic Table 2.6 Molecules and Molecular Compounds 2.7 Ions and Ionic Compounds 2.8 Naming Inorganic Compounds 3.1 Conservation of Mass, Chemical Equations, and Stoichiometry 3.2 Formula Weights and Elemental Compositions of Substances 3.4 Avogadro’s Number and the Mole; Molar Mass 3.5 Formula Weights and Elemental Compositions of Substances 3.6 Reaction Stoichiometry 3.7 Limiting Reactants Chemistry Lecture #1, p. 9 Lecture 2 Next Week: Brown 10.1 Characteristics of Gases 10.2 Pressure 10.3 The Gas Laws 10.4 The Ideal Gas Equation 10.5 Gas Mixtures and Partial Pressures 10.6 The Kinetic-Molecular Theory of Gases 10.7 Molecular Effusion and Diffusion 10.8 Real Gases: Deviations from Ideal Behavior Chemistry Lecture #1, p. 10 soletsbegin Likemanysubjectschemistryhasitsownlanguageand terminologythatwehavetolearn Todaygoalsomebasics What is Chemistry? IIii Study of properties and behavior of matter Language of Chemistry? How do we describe matter? Letters? Atoms Smallest unit of an element Elements Substances made of only one atom type Words? Molecules Two or more atoms joined together Compounds Molecules with different types of atoms F eg fifer Sentences? Reactions Describe “chemical changes” i Chemistry Definition Ch stance eg exempli gratia forexample Lecture #1, p. 11 puresubstances theyhavedistinctpropertiesandcompositions Elementsmoleculesandcompoundsare thatdonotchangefromonesampletoanother wecandistinguishpuresubstancesfrommixtures Pure Substances versus Mixtures Pure substances Examples: elements, molecules, compounds Have fixed composition Composition does not change from sample to sample Mixtures? Contain two or more pure substances If uniform: homogeneous mixture If nonuniform: heterogeneous mixture Examples? Pure water is a pure substance Mineral water is a homogeneous mixture Milk is a heterogeneous mixture iiiiiiiii Chemistry Uniform means composition properties appearance isthesameeverywhere inmixture www.t.is i ii i i ii Lecture #1, p. 12 Atoms We now accept that matter is made from atoms, but not obvious! Dalton’s Atomic Theory (1803–1807) Each element composed of atoms All atoms of given element are chemically identical John Dalton,1766–1844 (wikipedia.org) Different elements composed of different atoms Atoms cannot be changed, created, or destroyed by chemical reactions Compounds involve combinations of atoms of 2 or more elements Explains Laws of... Constant Composition Conservation of Mass Multiple Proportions Chemistry Constantcomposition in agiven typeofatomsisfixed compound numberand ofMass conservation massdoesnotchangeduetochemicalreactions LawofMultipleProportions if it.fi s feanditffEntumf Pounds n Lecture #1, p. 13 Atomic Structure We now know atoms are made from even smaller subatomic particles... Electrons, protons, and neutrons charge mass electrons qe = −e me = 9.11×10−31 kg Marie Curie,1867–1934 Charged (wikipedia.org) protons qp = +e mp = 1.67×10−27 kg neutrons qn = 0 mn = 1.67×10−27 kg e = 1.60×10−19 C Intra electrically Notes: Atoms have equal number of protons and electrons d Protons and neutrons much heavier than electrons 18398 respectively These masses are tiny ⟶ inconvenient in kg wewillfix Chemistry thisshortly withan Lecture #1, p. 14 The Modern Picture of the Atom Nucleus protons and neutrons ∼10−4 Å 1 Å = 1×10−10 m Electron cloud 1–5 Å Nucleus incredibly dense! Cartoon nucleus not to scale! If matchbox had same density (1014 g/cm3) If electron cloud were football pitch, would weigh 2.6 billion tons! nucleus would be 1 mm in diameter Chemistry Lecture #1, p. 15 What Makes One Type of Atom Different from Another? Each type of atom has specific number of protons, given by its... Atomic number Number of protons in atoms of particular element Also, gives number of electrons (to keep charge neutrality) Ex’s: Carbon atoms have 6 protons, 6 electrons ⟶ atomic number 6 Oxygen atoms have 8 protons, 8 electrons ⟶ atomic number 8 Notes: Chemical properties of atom determined by its electrons! Atomic number gives number of What about neutrons? protons or electrons in an atom Chemistry Lecture #1, p. 16 Neutrons For specific element, number of neutrons in its atoms can vary... Isotopes Mass number Same element with different number of neutrons Affects mass of atom, but not its chemistry Number of protons plus neutrons in atom I Ex: Carbon: most common isotope has 6 neutrons ⟶ mass number 12 Atomic symbols Mass number ⟶ 12 Atomic number ⟶ 6 C ⟶ Atomic symbol iiiiiiiii Atomic number is redundant once symbol and mass number are given Chemistry Note I a Radioactivity exuranium Lecture #1, p. 17 Atomic Mass and Atomic Weight To avoid using kg’s and extremely small numbers, we define a new mass scale for atoms... Atomic mass New scale with 12C mass equal to 12 u 1 u = 1.660539040 × 10−27 kg (atomic mass unit, amu) protons neutrons electrons mass mp = 1.0073 u mn = 1.0087 u me = 5.486 × 10−4 u Atomic weight Average atomic mass of element in amu’s Use relative abundance of each isotope of specific element 12C 98.93% 13C 1.07% 14C trace Ex: Carbon: Atomic (0.9893⋅12 u) + (0.0107⋅13.0035 u) + trace weight of C = 12.01 u Chemistry Lecture #1, p. 18 Atomsorganizedintoatable DmitriMendeleev1869 The Periodic Table Lists 118 known elements In order of atomic number Gives symbol and atomic weight Columns known as “groups” In group: chemically similar behavior Rows known as periods Quantum mechanics explains shape Tan = metals Green = non-metals Purple = metalloids Chemistry Lecture #1, p. 19 Common Names Transition metals Lanthanides Actinides Rareear Chemistry Lutetium Lu71 is included in lanthanides Lawrencium Lr103 is included inactinides Lecture #1, p. 20 wewilldiscussionsshortly Molecules and Compounds Represent connectivity and shape? Only noble gases exist as isolated atoms Most matter exists as molecules or ions 3D Represent with chemical formulas shape? structural perspective formula drawing Even Best better Ball-and-stick space-filling model model Chemistry structuralformula is niceandsimple easytodrawanditshowsconnectivity Butnot3Dshape alsocaptures ii iiiiii Lecture #1, p. 21 Ions Ions are electrically charged atoms or molecules Cations have positive charge, i.e. electron(s) removed Anions have negative charge, i.e. electron(s) added Atoms at edges of periodic table: tend to match number of e−’s in noble gas Na atom Na cation ( 1+ ) Cl atom Cl anion ( 1− ) i.e. ≡ id est = “that is” e−’s ≡ “electrons” Note: atom’s size changes when ion forms Chemistry Notewewilluse theconvention asinthetextbook thatall ioniccharges are given inmultiples of ewithsignafterthenumber Examples Natt and cis Lecture #1, p. 22 Polyatomic Ions Ions made from a group of atoms Examples: Ammonium cation, NH4+ Sulfate anion: SO42− Ionic Compounds Formed between cation and anion Generally between metal and nonmetal Example: NaCl (table salt) NaCl solid Electrons transferred from metal to non-metal Oppositely charged ions then attract each other Compounds are electrically neutral If charges are unequal on cation and anion, balance charge with coefficients: Please read Brown 2.8: Naming Inorganic Compounds Chemistry Foranionicsolidwewriteitsempiricalformula Lecture #1, p. 23 Common Cations Chemistry Lecture #1, p. 24 Common Anions Chemistry Lecture #1, p. 25 Nowwehave lettersandwords whatabout sentences Chemical Reactions Describe changes from one substance to another Distinct from physical changes of same substance Ex: ice melting is not chemical reaction iiiiiii i Rules of chemical reactions: Atoms are neither created nor destroyed during reaction Energy may be required to start reaction Energy may be released or absorbed by reaction Described by chemical equations: reactants ⟶ products Each atom type must be balanced on both “sides” “go to” “produce” Chemistry B Lecture #1, p. 26 Stoichiometry How many reactants are consumed and products produced Ex: H2 + O2 H2O Releases useful energy Reactant #1 Reactant #2 Product Important reaction for future of our planet! Not balanced! 2H + 2O ≠ 2H + O Just counting atoms Balancing chemical equations: Either by 2 H2 + O2 2 H2O Often one can see coefficients “inspection”... needed to balance... or systematically ⟶ Chemistry Balance placing coefficients infrontofreactantsandproductslikeanalgebraicequation by Lecture #1, p. 27 Balancinganequation is alittlepuzzle tosolve Balancing Chemical Equations Systematic approach a H2 + b O2 c H2O a, b, c are unknown coefficients ! Balance requires a = c and b = c " ! Set a = 1 ⇒ c = 1 and b = ! H2 + O H2O " " 2 Or multiply all coefficients by 2... 2 H2 + O2 2 H2O Both balanced. You can always check! Note: To balance equation, change coefficients, not subscripts! H2 O ≠ H2 O 2 Chemistry Thiswas a simpleexample butreactionscanbemorecomplicated aswewillsee Lecture #1, p. 28 Inreallife wedon'ttypicallyhavetwoit moleculesreactingwithone amolecule Ratherweneedtodiscussmacroscopicquantities like gramsorkilograms Formula Weight We need to know mass of substances Formula weight (FW) is sum of atomic weights for all atoms in formula Ex: H2O FW of H2O = 2⋅(1.0 u) + 1⋅(16.0 u) = 18.0 u atomic weight atomic weight mass of one H2O molecule of hydrogen of oxygen in atomic mass units molecule ⇒ FW is called molecular weight, Mw If substance is ionic solid ⇒ For FW use empirical formula Ex: NaCl, CaCl2 Gives relative amount of atoms in compound in smallest whole-number ratio Chemistry Formulaweights are themassof a singlemolecule in atomicmassunits Remi i c Lecture #1, p. 29 P give imii featinhm 9m s w fi Ee.Y a it to knowhowmanymolecules Sample Problem How many grams of O2 can react with 2.00 g of H2? Reaction: 2 H2 + O2 2 H2O FW of H2 = 2⋅(1.00 u) = 2.00 u FW of O2 = 2⋅(16.0 u) = 32.0 u ii Strategy: convert units grams H2 amu’s H2 molecules H2 molecules O2 amu’s O2 grams O2 1 kg 1u 1 molecule H2 1⁄2 molecule O2 32.0 u 1.66×10"#$ kg 1000 g 2 g H2 ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ 1000 g 1.66×10"#$ kg 2.00 u 1 molecule H2 1 molecule O2 1u 1 kg 6.02×10#% molecules H2 3.01×10#% molecules O2 Answer = 16.0 g O2 Chemistry Lessons A Theanswer is not1.0g02 teculeof Big Int esofn.tt I tenfitmhast.es B Thisprocess istedious Is thereaneasierway Lecture #1, p. 30 Iii The Magnificent Mole 6.022140857×10!" ≡ -# ≡ Avagadro’s number Why this number? For convenience! Defined such that the atomic weight of any element in grams contains -# atoms i 19 One K atom has mass of 39.0983 u From periodic table: Potassium K 39.0983 g of K contains -# K atoms 39.0983 Known as 1 mole of K Also, molecular weight of any molecule in g’s contains -# of such molecules Formula weight then gives molar mass: grams / mole Useful! Chemistry formore abbreviation notes ma Note L I molecule giant it Lecture #1, p. 31 Letsreturnto stoichiometry Return to Stoichiometry i 1 mole is 6.02 x 1023 “items” Avogadro’s Number, NA Molar mass can be determined from formula weight Chemistry faccordingtothe i fc.ie n Lecture #1, p. 32 Connection to Research in D-MAVT Prof. Nicolas Noiray Use renewable H2 in modern high-efficiency turbines for electricity production? Exploit “power-to-gas” technologies that produce H2 with excess electricity from wind, hydro, or solar... Electrolysis: 2 H2O (ℓ) 2 H2 (g) + O2 (g) Store H2 until needed Turbine: 2 H2 (g) + O2 (g) 2 H2O (g) Produce electricity on demand Goal: sustainable, carbon-neutral cycle for electricity at peak demand Chemistry Next time Ideal Gas Law Chapter 10 Lecture #1, p. 33 What We Learned Topics: Elements, compounds, mixtures Atoms, atomic structure, atomic number, periodic table Mass number, atomic mass, isotopes, atomic weight Molecules, formulas, structural formulas, representations Ions, ionic compounds Chemical reactions, chemical equations, balancing equations Stoichiometry, formula weights Mole, Avogadro’s number, molar mass Chemistry

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