Chem Notes week 9
Chem Notes week 9 CHE 106 - M001
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CHE 106 - M001
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This 0 page Class Notes was uploaded by Andrea Scota on Sunday November 1, 2015. The Class Notes belongs to CHE 106 - M001 at Syracuse University taught by R. Doyle in Fall 2015. Since its upload, it has received 56 views. For similar materials see General Chemistry Lecture I in Chemistry at Syracuse University.
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Date Created: 11/01/15
Pink mentioned in class Chem Notes Week 9 TEXTBOOK CHAPTER 7 sections 7174 Periodic Properties of the Elements Development of the Periodic Table 71 Mendeleev and Meyes 1869 published nearly identical classi cation schemes for classifying elements 0 Similar chemical and physical properties recur periodically when elements are arranged by periodic weight 0 Mendeleev insisted that elements with similar properties be in the same column he actually left some spots blank where he though elements may be missing 0 Mostly developed the concept of an atomic number each element has one added more order and clari ed the periodic table 0 Now we recognize that elements in the same column of the periodic table have the same number of electrons in their valence orbitals this similarity leads to similarities among elements of the same group 0 Differences in elements in same groups arise because their valence orbitals are in different shells Effective Nuclear Charge 72 0 Many properties of atoms depend on electron con guration and how strongly their outer electrons in the atoms are attracted to the nucleus 0 Columbus Law tells us the strength of this interaction depends on the magnitude of charges and distances between them 0 Each electron in a many electron atom is screened from the nucleus by the other electrons experiences less new attraction than it would if other electrons weren t there electronelectron repulsion also plays a role in this o Zeff many properties of atoms depends on this is the portion of the nuclear charge that an outer electron experiences after accounting for repulsions by other electrons in an atom o Z is atomic number S is screening constant usually close to number of inner electrons 0 Core electrons are very effective in screening outer electrons from the full charge of the nucleus 0 Electrons in the same shell don t screen each other effectively Because actual nuclear charge increases as we progress through a period the effective valence electrons increase as we move left to right across a period Sizes of Atoms and Ions 73 Can de ne atomic size in several ways based on distances between atoms in various situations Shortest distance separating 2 nuclei of colliding atoms is twice the radii of the atoms called the nonbinding atomic radius or van der Waals radius Atomic radius based on measurement of the distances separating atoms in their chemical compounds Size of an atoms can be gauged by its bonding atomic radius the size of an atom 0 Equal to 12 the bond distance d o Is smaller than the nonbonding atomic radius 0 In general atomic radii increase as we go down a column in the periodic table and decrease as we move left to right across a period Ionic radii can be determined by interatomic distances in ionic compounds Cations are smaller that their parent atoms because electrons are remover from their atomic orbital and the electronelectron repulsions are reduced Anions are larger than their parent atoms For ions carrying the same charge ionic radius increases as we move down a column in the periodic table 0 As the principle quantum number increases of the outermost occupied orbital the radius increases as well Isoelectronic series is a series of ions that has the same number of electrons can list in order of increasing atomic number in which nuclear charge increases and the ionic radius decreases o For such series size decreases with increasing nuclear charge as the electrons are attracted more strongly to the nucleus if 167 190 243 RI 265 C5 293 Metals D F Be 112 g Semimetals Nonmetals 4 2 Mg Cl 145 T9 Ca 5 Ti Cr Fe Co Ni 39Cu Zn Br Kr 194 17 6 166 155 15 2 142 94 38 Ba Sr r Zr Nb Mo Tc u Rh Pd Ag Cd ln Sn I lie r 7 7 1 219 212 2116 1198 191 183 173 113 169 155 155 156 14539 133 123 115 103 La 39 Hf Ta w a Re i 70 Ir Pt 1 Au Hg 1 u Pb Po Rn 35 127 Bi 253 208 200 1 93 183 135 180 W7 174 171 143 1 120 Ionization Energy 74 Ionization energy of an atom or ion is the minimum energy required to remove an electron from its ground state of the isolated gaseous atom or ion essentially forming a cation 0 1St ionization energy is the energy needed to remove the rst electron from a nuclear atom 0 2r101 ionization energy is the energy needed to remove the second electron from a nuclear atom etc Ionization energies show a sharp increase once all the valence electrons have been removed because of the much higher effective nuclear charge experienced by the core electrons First ionization energies show periodic trends that are opposite those seen for atomic radii with smaller atoms having a larger rst ionization energies 0 First ionization energies decrease as we go down a column and increase as we proceed left to right across a row Can write electron con gurations for ions by rst writing the ground state of a neutral atom and them removing or adding the appropriate number of electrons o Cations electrons removed rst from orbitals of neutral atom with the largest value of n If 2 valence orbitals with the same values of n 4s4p then electrons are lost from orbital with higher 1 value rst 0 Anions electrons added to orbitals in reverse order gt 3205 32036 34 Se WAG 52 Te 1 m TELLUHJIM Incmeases smammu 2m 7 as 24 r as Sc V Br Fe 965 50942 SIBBB 55845 5mm WNW IN WWII Iii 38 Ill 42 44 Y Nh Mo Ru 36996 93906 959 EM mm NIDBIJII quotINNEan IIIJ39wl39lEHIEIH 51111 23 TB La39lLiJi39 Ta W WES 095 19184 90233 GSIIIJII ma WNUNIEIJUM 2W Increases
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