Lexi Eyerman – AP CHEM SUMMARY 29 Sept. 2011 AP CHEMISTRY: UNIT 2 [pgs. 198-273, chapters 6-7] I. Scientific Laws, Theories, and BIG Ideas a. The Wave Nature of Light i. Electromagnetic Radiation – energy carried through space (ex/ light) b. Dual-nature of Electrons & Photons i. Quantized Energy: Planck’s Constant (see Equations section); only a certain fixed quanta of energy is emitted (one/ a few fixed wavelengths) ii. Photoelectric Effect: light can be particle-like (photons) iii. Electrons have energy and frequencies associated with them and require a certain quanta of energy to change energy levels. c. Electrons i. Energy is negative and becomes less negative as you go outward ii. Writing electron configurations: 1. n = size of path (Principle Quantum Number, a.k.a. P.E.L) 2. l = shape of path (0=s, 1=p, 2=d, 3=f); n-1 = l 3. m = orientation of path (m= -l… +l) 4. ms = electron spin iii. No two electrons can have the same set of quantum numbers iv. Hund’s rule: draw spin up before spin down v. No more than 2 electrons per orbital vi. Magnetic properties 1. Ferromagnetism – unpaired electrons attracted into magnetic field 2. Paramagnetism – unpaired electrons attracted into magnetic field (induced; ex/ Al, Mn, Sc, Y, lanthanides) 3. Diamagnetism – all electrons are paired; no attraction to magnetic field (noble gases) d. Periodicity i. Effective nuclear charge – the number of protons in nucleus minus the avg. number of electons between the nucleus and electron in question 1. Coulomb’s law: attraction affected by difference in charge and distance/ size ii. Cation: positive; size = smaller; anion = negative; size = larger iii. Isoelectronic series = ions that have same number of electrons iv. First Ionization energy = energy required to remove first electron from a neutral atom v. Electronegativity = electron affinity; the attraction of an atom for an electron vi. Groups/ Types of elements Lexi Eyerman – AP CHEM SUMMARY 29 Sept. 2011 1. Metals = majority of elements; shiny; conduct heat & electricity; malleable, ductile, solids at room temp; reducing agents a. Alkali: group 1; react violently with water b. Alkaline Earth: group 2; react with water 2. Nonmetals = poor conductors of heat and electricity; diatomic (7H club); oxidizing agents a. Halogens: group 7 3. Metalloids = in-between metals & nonmetals Ionization Energy decreases Electronegativity decreases = nonmetals = metals = metalloids = Lanthanide series = Actinide series II. Ionization Energy increases Electronegativity increases Equations & Calculations 𝑚 a. Speed of light = c = 3.00 × 108 𝑠 ; use in wavelength & frequency calc (below); b. 𝑐 = 𝜆𝜈 ; c= speed of light, = wavelength (m); = frequency (hertz = 1/s) i. Wavelength and frequency are indirectly related ii. Speed remains constant c. 𝐸 = ℎ𝜈 ; E= energy, h = Planck’s constant (6.63 × 10−34 𝐽 ∙ 𝑠); = frequency i. Used to determine energy of a photon of a certain or ii. Direct relationship between frequency and energy 𝑄 𝑄 d. Coulomb’s law: 𝐹 = 𝑘 𝑟1 2 2 ; F=force, k= a constant, Q = charge, r = distance i. Used to determine attraction: positive = repulsive, negative = attractive force 1 e. 𝐸 = (−2.18 ∙ 10−18 𝐽)(𝑛2 ) ; E = energy; n = principle energy level i. Used to determine energy of an electron in a certain state 1 1 f. ∆𝐸 = (−2.18 ∙ 10−18 𝐽)(𝑛2 − 𝑛2 ); nfinal = final P.E.L. of electron 𝑓𝑖𝑛𝑎𝑙 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 i. Used to determine the amount of energy released/ absorbed when an electron is moving into/ out of an excited state ii. Negative = energy released; positive = energy absorbed III. Favorite Topic: The Periodic Table – I like to see the relationship between different elements and like to pick out patterns. Lexi Eyerman – AP CHEM SUMMARY IV. 29 Sept. 2011 Least Favorite Topic: Magnetism – it seemed random and unrelated.