The Periodic Table 1 The Periodic Table y Development of the periodic table (8.1) y Periodic classification of the elements (8.2) y Periodic variation in physical properties (8.3) y Ionization energy (8.4) y Electron affinity (8.5) y Variation in chemical properties of the representative elements (8.6) 8.1 and 8.2 Development of the periodic table and periodic classification y In what year was the modern periodic table developed? y How was the periodic table put together? ns1 4f 5f ns2 the Elements Electron Configurationsof Ground State d1 d5 d10 ns2np1 ns2np2 Figure 8.1, p. 255 p. 8.1, Figure ns2np3 ns2np4 ns2np5 ns2np6 8.1 and 8.2 Development of the periodic table and periodic classification y In what year was the modern periodic table developed? y How was the periodic table put together? y In what year were electrons discovered? y In what year were protons discovered? 8.1 and 8.2 Development of the periodic table and periodic classification When the Elements Were Discovered When the Elements Were 8.1 and 8.2 Development of the periodic table and periodic classification Figure 8.2, p. 257 8.1 and 8.2 Development of the periodic table and periodic classification y What are core electrons? y How do these vary by period? He (2 core e-) Ne (10 core e-) Ar (18 core e-) Kr (36 core e-) Xe (54 core e-) 8.1 and 8.2 Development of the periodic table and periodic classification y What are valence electrons? y How do these vary by group? 12 345678 8.1 and 8.2 Development of the periodic table and periodic classification y How are electron configurations of ions determined and written? 8.1 and 8.2 Development of the periodic table and periodic classification Atoms lose Na [Ne]3s1 Na+ [Ne] electrons so that Ca [Ar]4s2 Ca2+ [Ar] cation has a noble- gas outer electron 2 1 3+ Al [Ne]3s 3p Al [Ne] configuration. Atoms gain H 1s1 H- 1s2 or [He] electrons so 2 2 5 - 2 2 6 that anion has F 1s 2s 2p F 1s 2s 2p or [Ne] a noble-gas O 1s22s22p4 O2- 1s22s22p6 or [Ne] outer electron configuration. N 1s22s22p3 N3- 1s22s22p6 or [Ne] Anions of Representative Elements Electron Configurations of Cations and +1 +2 Representative Elements Anions Of Cations and +3 Figure 8.1, p. 255 p. 8.1, Figure -3 -2 -1 8.1 and 8.2 Development of the periodic table and periodic classification When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n –1)d orbitals. Fe: [Ar]4s23d6 Mn: [Ar]4s23d5 Fe2+: [Ar]4s03d6 or [Ar]3d6 Mn2+: [Ar]4s03d5 or [Ar]3d5 of Transition Metals of Transition Fe3+: [Ar]4s03d5 or [Ar]3d5 Electron Configurations of Cations 8.1 and 8.2 Development of the periodic table and periodic classification y How are electron configurations of ions determined and written? y What is isoelectronic? y Which species are isoelectronic? Na K Na+ K+ Ca2+ Ti4+ Ne Al3+ S2– Cl– Cl Ar O2– Sc2+ Kr 8.3 Atomic and Ionic size y Do all electrons feel the same nuclear charge? y What is shielding? y What is effective nuclear charge? 8.3 Atomic and Ionic size Na Mg Al Si P S Cl Z 11121314151617 Core 10 10 10 10 10 10 10 Zeff 1234567 σ 8.8 9.15 9.5 9.85 10.2 10.55 10.9 Zeff 2.2 2.85 3.5 4.15 4.8 5.45 6.1 Effective Nuclear Charge Effective 8.3 Atomic and Ionic size Li Na K Rb Cs Fr Z 3 11 19 37 55 87 Core21018365486 Zeff 111111 σ 1.7 8.8 16.8 33.3 51.3 81.2 Zeff 1.3 2.2 2.2 3.7 3.7 5.8 Effective Nuclear Charge Effective 8.3 Atomic and Ionic size Effective Nuclear Charge (Zeff) increases across a period from left to right ) increases ) increases eff Z Effective Nuclear Charge Effective down a group from top to bottom from a group down Effective Nuclear Charge ( Effective Margin Figure, p. 259 8.3 Atomic and Ionic size y Do all electrons feel the same nuclear charge? y What is shielding? y What is effective nuclear charge? y How does this affect the size of atoms? ◦ How do we determine the size of atoms? 8.3 Atomic and Ionic size Radius = ½ the distance between the centers of the atoms Figure 8.3, p. 260 8.3 Atomic and Ionic size Atomic size decreases across a period from left to right Atomic Size from top to bottom from Atomic size increases down a group a group down Atomic size increases Figure 8.2, p. 257 8.3 Atomic and Ionic size y Do all electrons feel the same nuclear charge? y What is shielding? y What is effective nuclear charge? y How does this affect the size of atoms? ◦ How do we determine the size of atoms? y How does atomic size change when ions form? 8.3 Atomic and Ionic size Cation is always smaller than atom from which it is formed. Anion is always larger than atom from which it is formed. Figure 8.7, p. 262 8.3 Atomic and Ionic size Ionic Size Figure 8.6, p. 262 8.3 Atomic and Ionic size Ionic Size Figure 8.8, p. 263 8.4 Ionization energy y What is ionization energy? y What is the periodic trend for ionization energy? 8.4 Ionization energy Ionization Energy increases across a period from left to right group from top to bottom from group Ionization Energy decreases down a down Ionization Energy decreases Margin Figure, p. 265 8.4 Ionization energy Figure 8.9, p. 266 8.4 Ionization energy y What is ionization energy? y What is the periodic trend for ionization energy? y What is the difference between 1st and successive ionization energies? 8.4 Ionization energy Table 8.2, p. 265 8.5 Electron Affinity y What is electron affinity? y How can this be represented in a thermochemical equation? Table 8.3, p. 268 8.6 Descriptive Chemistry y Read p. 268-278 y You will be tested on only those concepts that you have already been tested and/or taught. For example: ◦ The electron configuration of calcium ◦ The reaction of sodium with water ◦ The metallic character periodic trends (consider group 4) Chapter 8 – Practice.