Slide 1

THE PERIODIC TABLE & ELECTRON CONFIGURATION Chapters 4 & 5 Slide 2 Slide 3 The Element Song Slide 4 Dimitri Mendeleev Invented periodic table Organized elements by properties Arranged elements by atomic mass Predicted existence of several unknown elements Element 101 Slide 5 Mendeleevs Early Periodic Table GRUPPE I GRUPPE II GRUPPE III GRUPPE IV GRUPPE V GRUPPE VI GRUPPE VII GRUPPE VIII ___ ___ ___ ___ RH 4 RH 3 RH 2 RH R 2 O RO R 2 O 3 RO 2 R 2 O 5 RO 3 R 2 O 7 RO 4 REIHEN 1 2 3 4 5 6 7 8 9 10 11 12 Annalen der Chemie und Pharmacie From Annalen der Chemie und Pharmacie, VIII, Supplementary Volume for 1872, p. 151. H = 1 Li = 7 Be = 9.4 B = 11 C = 12 N = 14 O = 16 F = 19 Na = 23 Mg = 24 Al = 27.3 Si = 28 P = 31 S = 32 Cl = 35.5 K = 39 Ca = 40 ? = 44 Ti = 48 V = 51 Cr = 52 Mn = 55 Fe = 56, Co = 59, Ni = 59, Cu = 63 (Cu = 63) Zn = 65 ? = 68 ? = 72 As = 75 Se = 78 Br = 80 Rb = 85 Sr = 87 ? Yt = 88 Zr = 90 Nb = 94 Mo = 96 __ = 100 Ru = 104, Rh = 104, Pd = 106, Ag = 108 (Ag = 108) Cd = 112 In = 113 Sn = 118 Sb = 122 Te = 125 J = 127 Cs = 133 Ba = 137 ? Di = 138 ?Ce = 140 __ __ __ __ __ __ __ ( __ ) __ __ __ __ __ __ __ __ ? Er = 178 ? La = 180 Ta = 182 W = 184 __ Os = 195, Ir = 197, Pt = 198, Au = 199 (Au = 199) Hg = 200 Tl= 204 Pb = 207 Bi = 208 __ __ __ __ __ Th = 231 __ U = 240 __ __ __ __ __ TABELLE II Slide 6 Examples of Mendeleevs Slide 7 Modern Periodic Table Henry G.J. Moseley Determined the atomic numbers of elements from their X -ray spectra (1914) Arranged elements by increasing atomic number Slide 8 Modern Periodic Table Elements are arranged in seven horizontal rows, in order of increasing atomic number from left to right and from top to bottom Rows are called periods Elements with similar chemical properties form vertical columns, called groups, Groups 1, 2, and 13 through 18 are the main group elements transition elements: groups 3 through 12 are in the middle of the periodic table Inner transition elements: The two rows of 14 elements at the bottom of the periodic are the lanthanides and actinides Slide 9 Groups to Know Group 1 = Alkali Metals Group 2 = Alkaline Earth Metals Group 17 = Halogens Group 18 = Noble Gases Slide 10 World of Chemistry Slide 11 IONS Positive and negative ions form when electrons are transferred between atoms Cation: an ion with a + charge Example: Na + Ca 2+ Anion: an ion with a charge Example: O 2- F - Slide 12 ELECTRONEGATIVITY Electronegativity describes how electrons are shared in a compound The high number means the element has a greater pull on electrons Fluorine is the most electronegative element Slide 13 SUMMARY OF PERIODIC TRENDS Figure 6.22 Slide 14 Light, Energy, and Electrons e-s are arranged in energy levels (e.l.s), at different distances from nucleus Close to nucleus = low energy Far from nucleus = high energy Slide 15 Rules for placing e-s in energy levels e-s in highest occupied level are valence e-s Only so many e-s can fit in a particular e.l. e-s fill lower e.l.s before being located in higher e.l.s* Ground state is the lowest energy arrangement of e-s. * There are exceptions we will learn later!) Slide 16 Light, Energy, and Electrons e-s can jump to higher energy levels if they absorb energy. They cant keep the energy so they lose it and fall back to lower levels. When they do this, they release the energy they absorbed in the form of light. Slide 17 Light, Energy, and Electrons (See p 129 of text ChemI/IH) Electron energy levels are like rungs of a ladder. Ladder To climb to a higher level, you cant put your foot at any level, you must place it on a rung Electron energy levels e-s must also move to higher or lower e.l.s in specific intervals Slide 18 Bohr Model of the Atom (dont copy this slide) Interactive Bohr Model Interactive Bohr Model Slide 19 Light, Energy, and Electrons Quantum-the amount of energy required to move an electron from one E.L. to another. Slide 20 Atomic Emission Spectrum (A.E.S) Each element emits a color when its excited e- s fall back. Pass this light thru a prism, it separates into specific lines of color. You can identify an element by its emission spectrum! (no 2 elements have the same AES) Slide 21 Emission Spectra of H, He, Ne (dont copy this slide) Slide 22 Use of e- waves (dont copy this slide) Electron microscope magnifies tiny objects b/c e- wavelength much smaller than visible light snowflake Slide 23 Heisenburg Uncertainty Principle Def: if you want to locate something, you can shine light on it When you do this to an electron, the photons send the e- off in an unpredictable direction (def):Therefore, you can never know BOTH the position and velocity of an e- at the same time Slide 24 Electron Sublevels Each electron has an address, where it can be considered to be located in the atom. Main energy level (principal quantum #) = hotel Sublevel = floor Orbital = room Regions of space outside the nucleus All orbitals in a sublevel have the same energy 2 electrons max can fit in an orbital Slide 25 Sublevels in Atoms See Fig 7.5 on p 235 Main energy level Types of sublevels # of orbitals# of electrons 1s1 2spsp 1 3 (4 total) 3spdspd 1 3 5 (9 total) 4-7spdfspdf 1 3 5 7 (16 total) Slide 26 Orbitals s orbitals are spherical There is only 1 orbital p orbitals are dumbbell shaped There are 3 orbitals, all with = energy Each is oriented on either x, y, or z axis They overlap d orbitals have varying shapes There are 5 orbitals, all with = energy f orbitals have varying shapes There are 7 orbitals, all with = energy Slide 27 Electron Configurations (dont have to copy. Info in prior slide) Electrons are always arranged in the most stable (lowest energy) way This is calledelectron configuration or ground state Slide 28 The Periodic Table & Atomic Structure Shape of p. table is based on the order in which sublevels are filled REGIONS OF THE P. TABLE (see p 244 of book) s REGION (block) - Groups 1 & 2 p REGION (block) - Groups 13-18 d REGION (block)- Groups 3-12 (Transition Elements) f REGION (block)- (Inner Transition Elements) Slide 29 Regions or Blocks of the P. Table (dont need to copy) Slide 30 Writing e- Configurations for Elements Using the P. Table 1. Always start with Period 1-go from L to R. 2. Go to Period 2-from L to R 3. Go to Period 3- from L to R 4. Continue w/Periods #4-7, L to R, until you arrive at the element you are writing e- configuration for. Exception: elements in d block are 1 main E.L lower than the period where they are located Exception: elements in f block are 2 main E.L.s lower than the period where they are located Slide 31 Correct Order of Sublevels (lowest to highest energy) 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p Slide 32 e- configurations 1. Use the P. Table to write the sublevels in increasing order. 2. Add a superscript next to each sublevel that shows how many e-s are in the sublevel 3. Ex: Hydrogen: 1s 1 Helium: 1s 2 Lithium: 1s 2 2s 1 Oxygen: 1s 2 2s 2 2p 4 Slide 33 Identifying Valence e-s Valence e-s are the electrons in the highest occupied main energy level. (dont copy. In prior slide) Identify them by finding the biggest big number in your e- configuration. Ex: Oxygen: 1s 2 2s 2 2p 4 There are 6 valence e-s in the 2nd main energy level (valence level) Slide 34 Why are d & f block elements sublevels out of order? When you get to the higher main E.L.s, the sublevels begin to overlap. Slide 35 Exceptions: Some Transition Elements (dont need to copy) Titanium - 22 electronsNORMAL 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 Vanadium - 23 electronsNORMAL 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 3 Chromium - 24 electronsEXCEPTION 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 4 is expected But this is wrong!! Slide 36 Chromium is actually (copy this!) 1s 2 2s 2 2p 6 3s 2 3p 6 3d 5 4s 1 3d 5 4s 1 Instead of 4s 2 3d 4 There is less repulsion (lower energy) in the 2 nd arrangement 4s3d Slide 37 Noble Gas Notation Short-cut way of showing e- configuration A Noble Gas is a Group 18 element. 1.Identify the noble gas in the period above your element of interest. Write this symbol in brackets. 2.Write the e- configuration for any additional e-s that your element of interest has, but the noble gas doesnt have. Ex: Nitrogen: 1s 2 2s 2 2p 5 becomes [He] 2s 2 2p 5 Slide 38 Arrow Orbital Diagram- Used to show e- configuration. SYMBOLS: A box represents an orbital Label each box with the sublevel: 1s 2s 2p 2p 2p An arrow represents an electron 2 arrows (e-s) in the same orbital face opposite directions. Example: oxygen, see above Slide 39 Arrow Orbital Diagram- Used to show e- configuration, cont. INSTRUCTIONS: Fill electrons from lowest to highest sublevel. Never place 2 e-s in the same orbital of a sublevel until you have placed one in each of the orbitals (Hunds Rule)