AP Chem review Big Idea 1

Info Schedule of review sessions During review sessions Cover Big Idea from review book Keep track of what we need to memorize Work on questions from review book Test taking strategies I’ll put info on Edmodo After march 1- not sure if afterschool review will stay on Friday Available in my room anytime (flex or after school) answers to WKSTs and test etc. I’ll review on Tuesdays but if you want to come to flex on other days to work in groups or check keys – sign up- my spring semester students will get my attention first on M,W,Th HW Reading from review book Diagnostic test Practice tests Lab info if want to write in lab notebook Practice WKSTs

Test Taking Strategies Test in 2 parts 90 min each Part 1 – 60 mc questions No calculator so math should be easy(ish) Access to PT and equation sheet 3 pass system 40 min 10 min Don’t leave any blank- GUESS at end (educated guess is better)

Test Taking Strategies Part 2- free response 7 questions- 90 minutes total 3 long – 17 to 20 min each 4 short – 7 to 10 minutes each Calculators allowed PT and equation sheet allowed They give partial credit- answer any part you know Math Type If multi-part and need answer from a to do b and can’t do a... But you can do b make up a # to insert-explain why you did it- you get credit! Units Don’t squeeze answers up near questions, use space provided at bottom Be neat and organized Free response (wordy) type DEFINE what they are asking for. Ex. Ionization energy Step by step approach is easier for grader to find your correct answer

Big idea 1 Molar mass or sometimes called atomic weight – units gram/mol

Mole Relationships Liters Mole Grams Atoms or molecules 6.02 x 1023 22.4 L 6.02 x 1023 22. 4 L Mole Mole Relationships Atomic Mass Grams 6

Mass spectrometry Isotope = form of element with a different # of neutrons Mass spectrometry = a techniques used to analyze various isotopes of an element

Percent composition Ex. Ca(NO3)2 # atom mass Total mass % composition

Percent composition Total= 164 Ex. Ca(NO3)2 # atom Total mass 40 40x1=40 40/164 x100=24.5% N 2 14 2x14=28 28/164 x100 = 17% O 6 16 6x16=96 96/164 x 100 = 58.5% Total= 164

Electron Configuration Energy of electrons is “quantized” –like steps e configuration (1s2..etc) Rules Lower fill 1st 1 e- per box, then double up Spin in opposite direction Noble gas configuration What is e- config for Si? Noble gas config for Si?

Coulomb’s Law E= (q)(q) r E = energy of electron Roughly inverse prop. No calculations but need to apply it logically. If electron is closer to nucleus the radius is small and Energy is big More charge on nucleus- more energy

Electrons as a wave E=hv c=lv E= energy h is planks’ constant (on eq sheet) l is wavelength v is frequency l and v inverse prop 1nm = 1 x10-9 m 1m = 1 x 109 nm

Ionization energy (IE) Definition= when atom exposed to high energy radiation (like a photon) it can remove an electron Closer electron is to nucleus = higher IE For the AP exam ionization energy and binding energy are synonymous terms This energy can be Joules (J) or electron volts (eV)

Photoelectron spectroscopy (PES) Incoming radiation energy = binding energy + Kinetic energy (of the ejected electron) Radiation energy is energy used to remove an electron Any energy not used in breaking electron free from nucleus is converted into kinetic energy for the ejected electron The faster an ejected electron is going- the more kinetic energy it has Hi KE = hi velocity We can use the kinetic energy to predict how close electron is to nucleus Faster e- ejection speed = hi KE = low binding energy = farther from nucleus Low KE implies closer to nucleus

Problem: Identify the element represented by the following photoelectron spectrum: Look at x-axis- high Energy is closer to nucleus Look at peak heights Relate to e- configuration (1s2..etc)

Trends Zeff = Z- S Zeff =effective nuclear charge Z = # protons Atomic radius- Define As go down period b/c you add an energy shell DECREASE left to right b/c less shielding as add electron to same shell Cations smaller than original (Ex. Mg2+ loses 2 e- and shell collapse) Anions bigger than original Isoelectric (same # e- ) series bigger proton, bigger Zeff= # smaller atom Zeff = Z- S Zeff =effective nuclear charge Z = # protons S = # core electrons Bigger Zeff smaller atom

Ionization energy Definition = Energy needed to remove outer most electron

Electronegativity Definition = How strongly atom attracts an electron from another atom

What to Memorize Coulomb’s law E= (q)(q) l and v inverse prop 1nm = 1 x10-9 m Zeff = Z- S (proton- core electrons) trends