Dr. Stéphanie Le ClairEmail: [email protected] Hours: Mondays 4-5PM and Fridays 4-5PM Office: 103 WhitmoreOR e-mail me to schedule an appointment and provide 3 time slots that work for you. Use your psu email address when emailing me and put Chem 110 in the subject.Have your clickers and materials out before class starts.12Classification of matterMatterMixturesPure substancesCan it be separated by physical means?Is the composition uniform?Heterogeneous mixturesHomogeneous mixturesSeparation by physical meansPure substancesCan it be decomposed by chemical means?ElementsCompoundsNoYesYesNoYesNoChemical combination of two or more elementsPhysical means: use the substances’ differing physical properties; e.g. density, solubility, melting point, etc.Chemical means: use a reaction; e.g. combustion, reaction with acid, etc.Pure substances3F01-3-5 (found in Lesson 01-3)4What is an atom composed of? Subatomic particles• Experiments found that both charged and neutral particles make up the atom.• The particles found in the atom are called “subatomic particles.”• The following three subatomic particles affect chemical properties:5SymbolMass(amu)Charge(au)Protonp+ElectronNeutronnwhere:• 1 amu = 1 atomic mass unit = 1.66054 x 10-24g (or 1 g = 6.022114 x 1023amu) We define the mass of 12C as exactly 12 amu, so 1 amu = 1/12 mass of carbon~1+1e-~10-10.0005How many subatomic particles?• Nucleons: particles found in the nucleus (protons and neutrons)• Atomic number: • Mass number: 6  612Ctell the identity of elementthe # of p+ in the nucleustotal # of p +n= total # of nucleonsmass#=#p+#nAtomic symbolatomic massatomic #What is the structure of the atom?7An atom is almost entirely empty space.Atom Diameter = 0.1-0.5 nm ~ 10-14 mNuclear diameter = 10-5nm = 10-10 mAtom diameter = 10,000 x nuclear diameter 1 nm = 10-9m 10 Å = 1 nm Å= angstromF01-1-1Putting it into perspective:The size of the nucleus relative to the atomLet’s say the nucleus has a diameter the size of a mechanical pencil eraser:How big would the diameter be for entire atom?6 mm x 10,000 = 60,000 mm x 1 m1000 mm= 60 m diameter 86 mmIons versus neutral atoms• Atoms can lose or gain electrons to become more stable (more on this later!)• For neutral atoms: # of protons # of electrons• For ions: # of protons # of electrons• Anions have a net ____________ charge  _____________ of electrons• Cations have a net ______________ charge  _______________ of electrons9Formation of anion Formation of cationF01-3-1=positivenegativeexcessdeficiencyClicker question (clicker frequency AD)How many protons, electrons and neutrons does a 57Fe3+ion have?10A. 57 neutrons, 26 protons and 23 electronsB. 31 neutrons, 57 protons and 57 electronsC. 31 neutrons, 26 protons and 26 electronsD. 31 neutrons, 26 protons and 23 electronsE. 57 neutrons, 26 protons and 26 electronsClicker questionWhich of the following statements is/are true regarding the number of protonsin an atom?I. It gives you the element’s atomic number.II. It gives you the number of electrons in a neutral atom.III. It gives you the identity of the element.IV. It changes based on the charge of the atom.11A.I and IIB.I and IIIC.IIand IIID.I, II, and IIIE.I, III and IVIsotopes• Isotopes are atoms that have the• Same # of: • Different # of: • For example, there are three naturally occurring isotopes of uranium: 234U, 235U and 238U. 235U is used for nuclear bombs and reactors.• The atomic mass/weight given on the periodic table is: 12proton (same element)neutrondifferent number of masssame atomic number, but different mass numberthe weighted average of atomic masses of naturally occuring isotopesIsotope abundance and atomic weightAvg. atomic weight = [ fractional natural abundance × isotope mass ]• The atomic weight and isotope mass are in units of ______. • If you are not given the exact isotope mass in a problem, use the _____________.• The natural abundance of isotopes can be given as a percent abundance or a fractional abundance.• The fractional natural abundance is the isotope abundance (0-1)• This is just the percent abundance as a decimal. Example: 83% is _________• .*Not on data sheet13*amumass number0.83the sum of fractional abundances =1Example calculationCarbon has two isotopes: 12C (98.93%) and 13C (1.07%). The mass of 13C is 13.00335 amu. What is the average atomic weight of carbon?Avg. atomic weight = [ fractional natural abundance × isotope mass ]Avg. atomic weight for C = (0.9893)(12 amu) + (0.0107)(13 amu)= 12.011 amu14Your turn: Clicker questionThe natural abundance of 79Br is 54.8%. What is the atomic weight of the onlyother isotope of Br?15A. 77 amuB. 78 amuC. 80 amuD. 81 amuE. 82 amu16Lesson 01-2 Avogadro’s numberWhat is this mystical thing called a “mole”?• Unfortunately, we cannot see atoms or molecules, or weigh individual atoms or molecules.• Instead, we can measure moles of atoms and molecules.• Definition: 1 mole is defined as the number of atoms in exactly 12 g of 12C.• NA= • 1 mole of something =Is that a lot?Bill Gates has a net worth of $76,000,000,000Avogadro’s number is 602,200,000,000,000,000,000,00017https://kidjeice.files.wordpress.com/2014/06/wpid-screenshot_2014-06-25-06-44-21.png?w=7056.02214 x 10^23 amu= Avogadro’s number6.02214 x 10^23 of somethingMOLE: Connection between microscopic (what we don’t see: atoms) and macroscopic (what we see)• Saying a “mole” is just like saying a “dozen.” It is just a way to count atoms, molecules, etc. • You can have one mole of anything.• 1 mole of atoms = • 1 mole of molecules = • 1 mole of particles =1818 g = 1 mole H2O6.022 x 1023molecules of H2O…MW = 18 amu6.02214 x 10^23 atoms6.02214 x 10^23 molecules6.02214 x 10^23 particlesWhat could we do with a mole of Hershey bars?• Given that one Hershey bar is 0.1365 meters long.• The Andromeda II galaxy is 2.13 million light years away from the Earth.• This corresponds to 2.02 x 1022meters• With a mole of Hershey bars (6.022 x 1023Hershey bars), we would be able to cover a distance of 0.1365metersHershey barx 6.022 x 1023 Hershey bars = 8.220 x 1022meters• This means we could build a bridge between Earth and the Andromeda II galaxy that would be four Hershey bars wide.• And we would still have 1.4 x 1021meters of Hershey bars left over, so the fifth layer could only span 7% of the way.19*not drawn to