ASRJC 2025 H2 Chem Periodic Table Notes

2025 ASRJC The Periodic Table (9729) 1 Illustration extracted from Concept of Chemical Periodicity: from Mendeleev Table to Molecular Hyper–Periodicity Patterns E. V. Babaev* and Ray Hefferlin+*Chemistry Department, Moscow State University, Moscow, 119899, Russia +Physics Department, Southern College, P.O. Box 370, Collegedale, TN 37315, USA ANDERSON SERANGOON JUNIOR COLLEGE 2025 JC2 H2 CHEMISTRY THE PERIODIC TABLE

2025 ASRJC The Periodic Table (9729) 2 LEARNING OBJECTIVES Trends and variations in atomic and physical properties For elements in the third period (sodium to chlorine), and in Group 2 (magnesium to barium) and Group 17 (chlorine to iodine): (a) Recognize variation in the electronic configurations across a Period and down a Group (b) Describe and explain qualitatively the trends and variations in atomic radius, ionic radius, first ionization energy and electronegativity: (i) Across a Period in terms of shielding and nuclear charge (ii) Down a Group in terms of increasing number of electronic shells and nuclear charge (c) Interpret the variation in melting point and in electrical conductivity across a Period in terms of structure and bonding in the elements (metallic, giant molecular, or simple molecular) (d) Describe and explain the trend in volatility of the Group 17 elements in terms of instantaneous dipole–induced dipole attraction Trends and variations in chemical properties For elements in the third period (sodium to chlorine): (e) (i) State and explain the variation in the highest oxidation number of the elements in oxides (for Na2O; MgO; Al2O3; SiO2; P4O10; SO3) and chlorides (for NaCl; MgCl2; AlCl3; SiCl4; PCl5) (ii) State and explain the variation in bonding in oxides and chlorides in terms of electronegativity (with the exception of AlCl3) (iii) Describe the reactions of the oxides with water (for Na 2O; MgO; A l2O3; SiO2; P 4O10; SO3) (iv) Describe and explain the acid/base behaviour of oxides (for Na 2O; MgO; Al2O3; SiO2; P4O10; SO3) and hydroxides (for NaOH; Mg(OH)2; Al(OH)3), including, where relevant, amphoteric behaviour in reaction with sodium hydroxide (only) and acids (v) Describe and explain the reactions of the chlorides with water (for NaCl; MgCl2; AlCl3; SiCl4; PCl5) (vi) Suggest the types of structure and bonding present in the oxides and chlorides from observations of their chemical and physical properties (f) Describe and deduce from E⦵ values the relative reactivity of elements of: (i) Group 2 as reducing reagents (ii) Group 17 as oxidising reagents (g) Describe and explain the trend in thermal stability of: (i) Group 2 carbonates in terms of the charge density of the cation and the polarisability of the large anion (ii) Group 17 hydrides in terms of bond energies In addition, students should be able to: (h) Predict the characteristic properties of an element in a given Group by using knowledge of chemical periodicity (i) Deduce the nature, possible position in the Periodic Table, and identity of unknown elements from given information of physical and chemical properties

2025 ASRJC The Periodic Table (9729) 3 Content Page 1 The Periodic Table 2 Trends of Physical Properties in the Periodic Table (SDL) 2.1 Atomic Radius (SDL) 2.2 Ionic Radius (SDL) 2.3 1st Ionisation Energy (SDL) 2.4 Electronegativity (SDL) 2.5 Melting and Boiling Points (SDL) 2.6 Electrical Conductivity (SDL) 3 Chemical Properties of Period 3 Elements and their Compounds 3.1 Oxides 3.1.1 Reactions with Oxygen (SDL) 3.1.2 General Properties of Oxides 3.1.3 Reactions of Oxides with Water 3.1.4 Reactions of Oxides / Hydroxides with Acids or Bases 3.2 Chlorides 3.2.1 Reaction with Chlorine (SDL) 3.2.2 General Properties of Chlorides 3.2.3 Reactions of Chlorides with Water 4 The Group 2 Elements 4.1 Introduction 4.2 Physical Properties 4.3 Chemical Properties 4.3.1 Reducing Power 4.3.2 Thermal Decomposition of Group 2 Carbonates 5 Real World Applications of Group 2 Compounds (SDL) 6 The Group 17 Elements 6.1 Introduction 6.2 Physical Properties 6.3 Variation in Volatility 6.4 Oxidising Strength of Halogens 7 The Group 17 Hydrides 7.1 Melting and Boiling Points 7.2 Thermal Stability of Group 17 hydrides 8 Uses of Group 17 elements and compounds (SDL) Annex 1 Annex 2 SDL (Watch lecture recording in MS Teams)

2025 ASRJC The Periodic Table (9729) 4 1. THE PERIODIC TABLE Dmitri Mendeleev’s Periodic Table, first published in 1869, which arranged elements according to atomic mass, was widely accepted. It was able to predict the properties of five undiscovered elements and their compounds, which provided proof of his periodic table. The elements had been listed and carefully arranged before Mendeleev did his. They had even been organized by similar properties before. So why is Mend eleev's periodic table the one that has endured? This was because Mendeleev correctly predicted “eka–aluminum”, an element yet to be discovered in his time, until years later. All these simply from where he suspected/expected this new element was to be located on his version of the Periodic Table. Today, there are 118 elements in the Periodic Table. Elements 113, 115, 117 and 118 newly added completing the Periodic Table. These elements were given the names nihonium (Nh), moscovium (Mc), tennessine (Ts) and oganesson (Og) respectively, officially in November 2016 by IUPAC.

2025 ASRJC The Periodic Table (9729) 5 A quick glance at the table shows a trend of elements in their respective groups such as electrical conductivity and reactivity. These trends, or periodicity, is the focus of this whole topic. Definition Periodicity refers to the repeating pattern of chemical and physical properties that is seen at regular intervals Elements are arranged in order of increasing atomic (proton) number. The properties of the elements are a periodic (i.e. repeating after a regular interval ) function of their atomic numbers. The Periodic Table can be segregated into 4 main blocks (s, p, d, f) , named according to the valence orbital of the elements at ground state level (i.e. when the electrons are not excited). Classification of Elements in the Periodic Table: (Refer to the Periodic Table on page 6.) Main group elements o Elements in Groups 1 and 2: s–block elements o Elements in Groups 13 to 18: p–block elements Transition elements o Elements in Groups 3 to 12: d–block elements o Elements with atomic numbers 58 – 71 & 90 – 103: f–block elements. Groups refer to the vertical columns of elements in the Periodic Table. o For Main Group elements, Group number = number of valence electrons (e.g. Group 13 = 3 valence electrons) o For Transition elements, Group number = number of valence electrons in the outermost s and d subshells (e.g. Group 3 = 3 valence electrons in the 3d and 4s subshells) o Elements in the same group have the same outermost electronic configurations in their atoms. o Hence, they have similar chemical properties. Periods refer to the horizontal rows of elements in the Periodic Table. o Period number = principal quantum number (n) of the valence electrons o Elements within the same period have the same number of quantum shells.

2025 ASRJC The Periodic Table (9729) 6 s block p block d block f block (n–1)d1ns2 (n–1)d2ns2 (n–1)d3ns2 (n–1)d5ns1 (n–1)d5ns2 (n–1)d6ns2 (n–1)d7ns2 (n–1)d8ns2 (n–1)d10ns1 (n–1)d10ns2 ns1 ns2 ns2np1 ns2np2 ns2np3 ns2np4 ns2np5 ns2np6

2025 ASRJC The Periodic Table (9729) 7 2. TRENDS OF PHYSICAL PROPERTIES IN THE PERIODIC TABLE (SDL) Recall the topic on ‘Atomic Structure’ how nuclear c