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Gr. 11 Review Structure of an Atom Contributions: The earliest ideas about matter and atoms were developed by Greek philosophers between 450 and 380 B.C. At that time, the question under discussion was whether matter had the property of being continuous or discontinuous. These concepts can be visualized if you took the "lead" or graphite of a broken pencil point and divided it in half, then divided that piece in half and again half of that piece. This process could be continued as long as possible. If matter was continuous, the process could be continued indefinitely without ever "running out" of graphite. If matter was discontinuous, then at some point, the dividing process would end when the last particle which could still be called graphite was all that remained. A further division would result in destroying the matter called graphite. Aristotle: matter is CONTINUOUS Democritus: matter is DISCONTINUOUS Dalton: Billiard ball model atom was a solid, indivisible sphere. Atoms of each element were identical in mass and their properties. Atoms of one element differed from that of another atom Thompson: raisin bun / grapes ‘n jello model discovered the electron Positively charged substance filled the atom. The electrons were arranged within this substance. Atom is mostly empty space Goldstein: discovery of proton Rutherford: nuclear atom Shot alpha particles (+ve) at gold foil, expected them to go through based on Thompson’s model Small % were reflected Hypothesized atom had a postive core – the nucleus, surrounded by mostly empty space containing negative charges Bohr: Solar System Model Found inconsistencies in previous models {Rutherford’s model did not account for the lack of emission of radiation as electrons move about the nucleus (at the rate an electron would lose energy, it would spiral into the nucleus) and the emission of light at only certain wavelengths (an accelerated electron should radiate energy at all wavelengths) Proposed electrons contained specific energies - referred to as energy levels The Atom Particle Charge Changing the number of this particle in an atom means…. Determining #p, #n and #e #p = atomic number #n = atomic mass - # p #e = atomic number ** in a ground state** Bohr Model Diagram Electrons fill specific energy levels around the nucleus Filling order - Determine the number of protons, neutrons and electrons of Neon p n e Now draw the bohr diagram Determine the number of protons, neutrons and electrons Now draw the bohr diagram Determine the number of protons, neutrons and electrons for Na +1 Cl-1 He +2 And draw a Bohr diagram for each. Schrodinger’s Quantum mechanical Model Based on mathematically determining the MOST PROBABLE LOCATION OF AN ELECTRON Consists of 4 numbers each giving more information about the probable location of an electron. Electrons act like particles and waves Instead of electrons following distinct paths (Bohr) electron waves are believed to occupy an orbital space (electron cloud) Based on: Heisenberg’s uncertainty principle: it is impossible to know both the location and the momentum of an electron Shrodinger: Quantum Mechanical Model Based on determining the MOST PROBABLE LOCATION of an electron Principle quantum number: (n) specifies the energy level of the electron N = 1,2,3,4 to infinity Azimuthal (Shape) Quantum Number (l): shape of orbital l = 0 ‘s’ orbital, spherical l=1 ‘p’ orbital – dumbbell l = 2 ‘d’ orbital – complex l = 3 ‘f’ orbital – complex l = 4 ‘g’ and continues through the alphabet Magnetic Quantum Number (m): spatial orientation - # of orbitals of a shape m = -1 … 0 … +1 * the NUMBER of ‘m’ values for a given ‘l’ value tells us the NUMBER of orbitals of that shape (given by the l-value) Spin Quantum Number (s): determines the spin of the electron + 1/2 clockwise - 1/2 counter clockwise In summary n = 1,2,3,4 …. to infinity L = 0,1,2,3 …. (n-1) 0,1,2,3…. S,p,d,f m = -1..0..+1 # of m values gives us # of orbitals as determined by l S = +1/2 CW -1/2 ccw Pauli’s exclusion Principle: NO TWO electrons can have the SAME set of quantum numbers THE QUANTUM MODEL ‘l’ value Shape n=1 l=0 ‘s’ orbital n=2 l=0 l=1 ‘s’ orbital ‘p’ n=3 l=0 l=1 l=2 ‘s’ orbital ‘p’ ‘d’ m=0 m = -1,0,+1 m = -2,-1, 0, +1, +2 N=4 l=0 l=1 l=2 l=3 ‘s’ orbital ‘p’ ‘d’ ‘f’ m=0 m = -1,0,+1 m = -2,-1, 0, +1, +2 m = -3,-2,-1,0,+1,+2,+3 Major Level n m value m=0 m=0 m = -1,0,+1 # of sublevels (different shaped) n 1 value 1 ‘s’ orb 1 value 3 values 1 ‘s’ orb 1 ‘p’ orb 1 value 3 values 5 values 1 ‘s’ orb 1 ‘p’ orb 1 ‘d’ orb 1 value 3 values 5 values 7 values # of orbitals (# of ‘seats’) n2 ** where ‘n’ represents any major level 1 ‘s’ orb 1 ‘p’ orb n value 1 ‘d’ orb 1 ‘f’ orb max. # of electrons 2n2 Describe the most probable location of an electron having the following set of quantum numbers: n = 3, l = 2, m = 1, s = +1/2 Describe the most probably location given the following sets of quantum numbers AND identify the ‘illegal’ set … JUSTIFY your choice(s). n l m s a) 2 0 0 +1/2 b) 3 2 -4 +1/2 c) 4 5 +2 -1/2 d) 6 3 -3 -1/2 e) 1 1 0 +1/2 f) 7 5 +3 +1/2 g) 5 3 +4 -1/2 Justification AUF-BAU PRINCIPLE Filing order for electron configuration 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 Aka spectroscopic notation Orbital board/box notation: write spec. notation first then transfer into boxes … watch out for Hunds’ Rule (half –fill with same spin before doubling up) ** NOTE: a POSTIVE ION is formed by REMOVING electrons from the OUTERMOST (VALENCE)LEVEL of a NEUTRAL ATOM … therefore when writing configuration for POSITIVE IONS .. First write the configuration for the NEUTRAL atom, then remove electrons from the OUTERMOST LEVEL… the final configuration may look like it has not follwed proper filling order .. That is okay (read the first statement in this paragraph) Give spectroscopic notation for: a) P b) Fe c) Cu+2 d) Cr+1 Give a) N b) Ca c) S orbital board notation for Give the set of quantum numbers for the LAST 2 electrons to enter a neutral sulphur atom (hint: first give spec. notation) Sketch an outline of a PT Label/identify: groups periods Metals Non-metals Alkali metals Alkaline earth metals halogens noble/inert gases transition/heavy metals s, p, and d block elements - On your OWN PT transfer the information in the chart on page 7 of your review, and the reactivity, ionization energy and atomic radius trends Atomic Radius (AR) Group As you go down a group Atomic Radius increases (because # of levels increases ∴ valence level is further away) Period As you go across a period Atomic Radius decreases (because nucleur charge, Protons, atomic numberis increasing creating a stronger force of attraction thereby `shrinking`the atom.. .note: as you go across a period valence level is the same) Ionization Energy(IE): the energy required to remove the valence (otermost) electron For a given species .. 1st IE<2nd IE<3rd IE 1st IE – energy required to remove 1st electron from outermost level 2nd IE – energy required to remove 2nd electron from outermost level a) b) c) Given the following ionization energies for element ‘X’: What group does ‘x’ belong to? Give 2 properties of ‘X’ Give the valence and lewis dot diagram for ‘X’ 1st IE = 10 2nd IE = 25 3rd IE = 300 4th IE = 380 5th IE = 780 Electronegativity: a measure of electron affinity (how much a species LOVES electrons) *does not include noble/inert gases Man-made scale:0-4, F is the most EN element IE/EN trends * identical in the PT IE/EN are large for small radii AR IE EN the larger the radius the smaller the IE/EN AR IE EN vice versa Group:as you go down a group IE/EN decreases because AR increase Period: as you across a period IE/EN increases because AR decreases Comparing anything: K, Ca, Mg, Na different groups and periods 1. Identify valence level for each species 2. Set up. small Ar large IE/EN large AR small IE/EN ** second Ionization trends How to: 1. Rip off one electron (may need to write out spec. notation) 2. Identify valence level for this set. 3. Do as before. Ex. Place from low to high 2nd IE Na, Mg, Li, Cl Ex. Place from low to high 2nd IE Na, Mg, Li, Cl Do questions in review package. Happiness is … 8 electrons Octet Rule: a species will react so as to achieve the electron configuration of the nearest inert gas ns2np6 8e- (exception He 1s2) Metal & non-metal bond Due to electron transfer (from the metal to the nonmetal) Attraction of oppositely charged ions Lewis Dot Diagrams: Write the lewis dot for each element (# of valence electrons) b) Transfer electrons ONE AT A TIME from the metal to the nonmetal, until metal has none and the non-metal has 8 (except for H…just 2) … bring in atoms of either species if needed c) Show the ions (and the number of each) formed d) Write the formula e) Name the compound .. Metal has the same name, non=metal ion takes on the ending ‘IDE’ Do EG. 18 on page 9 of review a) Eg. Na & O Non-metal/non-metal bond Due to sharing of PAIRS of electrons so each element will have 8 electrons on its’ valence level (except H – it will have 2) Lewis Dot – indicate the pairs shared Structural Formula: each pair shared is represented by a dash It will be easier to draw structural formula first, then replace each dash with a pair of electrons and then complete the octet around each element …. Remember the following rules: Group Group # of bonds (dashes) 4 5 6 7 4 3 2 1 Eg. HCN Isomers: same chemical formula but different structural formula Do questions 19 and 20, on page 10 of review Mole Avagrados’ #: 6.02 x 1023 Molar Mass (MM): mass of 1 mole of a given substance - g/mole Molar mass of elements : off PT – eg. Na 23 g/mole Molar mass of compound: add up all the elements MM of Mg3(PO4)2 = % composition % element A = MM of A x 100% MM of compound Eg. Mg3(PO4)2 % of Mg. Formulas: Mass = # mol x MM # moles = m / MM Eg. Det. Mass of 1.6 moles of NaOH Empirical/Molecular Formula and Hydrates Emprical formula (EF): simplest whole number ratio Ie. Sugar is C6H12O6 – EF is CH2O Molecular formula (MF): actual formula Sugar – C6H12O6 MF = (EF)n n = MM of MF/MM of EF Hydrates: compound with a definite # of water molecules LOOSELY attached to it … salt • X H2O, ratio is always one (1) salt: x (#) water Lets just get into it! GAS LAWS Boyles Law P1V1 = P2V2 Charles’ Law Daltons’ Law: partial pressures, pressure varies DIRECTLY with # of MOLES of gas particles PTOT = Pa + Pb + Pc NTOT = na + nb + nc Combined Gas Law: ** STP conditions refer ONLY to PRESSURE (101.3KPa) and TEMP (273K) Ideal gas law PV = nRT Lets get right into it – REVIEW QUESTIONS eg. 20 g of H2 and 30 g of N2 are placed in a 2L container at 400K. A) Determine PTOT B) Determine PH2 and PN2 Eg.2Na + 2H20 2NaOH + H2 What volume of H2 @ STP (T=273K, P= 101.3 Kpa) is formed when 10 g of Na is reacted? Do review questions STOICHIOMETRY – 13 LETTER WORD FOR FUN REMINDERS 1. BALANCE THE EQUATION!!! 2. Drop arrows 3. Determine your variables given 4. Find what is asked ? 5. FIND MOLES and use mole ratios. Eg. 2Na + 2H20 2NaOH + H2 What volume of H2 @ STP (T=273K, P= 101.3 Kpa) is formed when 10 g of Na is reacted? Review questions Solution Chemistry • Arrhenius Theory on ‘ions in solution’ • When a salt (any ionic substance) dissolves in water it breaks up into its’ ions • Concentration: • known as MOLARITY (M) • moles/litre … moles/L • moles/L = Molar • Molarity questions follow stoich • Formulae: • M = #moles/V • Dilution formula: MiVi = MfVf • Watch for – diluted TO vs diluted WITH • QUESTIONS Acid / Base Chemistry • Properties of • Acids Bases • Arrhenious Definition of: • Acid: a compound that ionizes (dissociates) IN SOLUTION to form (give) ____________________ • Base: an ionic _____________________ that dissociates IN SOLUTION to produce (give) ______________________ ions • ** presence of H+1/OH-1 ions IN SOLUTION give an Acid/Base its’ properties** • • Man made scale 0 – 14 • 0 -6.9 = 7= 7.1-14 =