Periodic Table, Chemical Bond Nature, and Nonclassical Compounds

ABSTRACT

The periodic table of the elements (PTE) is essential to understanding our nature and place in the whole of beings, food, drugs, materials, nanomaterials (NMs), etc. The ideas in the periodic table should be valued by the questions that they generate. A working guide with questions and answers was written to introduce the periodic table in chemical education and provide answers. The periodic table was related to electron configurations. Ql. Without looking at the periodic table but reminding the number of elements in every row (2, 8, 8, 18, 18, 32, 32), which elements have the atomic numbers 9, 10, 11, 17, 19, 35, 37 and 54? Etcetera. A need exists to develop the periodic-table research to understand periodic properties and periodic law (PL). The periodic table is empirical: more important than nomenclature are the facts of chemical behavior depending on the outer-core shells and frontier orbitals. It illustrates chemists’ ability to summarize infonnation in a two-dimensional (2D) representation. The most striking points of the periodic table continue to be: (1) the elements that occupy the same column present similar chemical properties; (2) the opposed behavior between both extreme groups (alkaline elements, halogens).

INTRODUCTION

Setting the scene: the periodic table of the elements (PTE), groups in PTE, working guide and the nature of chemical bonds in the new non-classical compounds and materials.

The PTE is essential to understand our nature and place in the whole of beings, food, drugs, materials, nanomaterials (NMs), etc. The ideas in PTE should be valued by the questions that they generate. A working guide with questions (Q) and answers (A) was written to introduce PTE in chemical education and provide answers. The PTE was related to electron configurations.

Ql. Without looking at PTE but reminding the number of elements in every row (2, 8, 8, 18, 18, 32, 32), which elements have the atomic numbers 9, 10, 11, 17, 19, 35, 37 and 54?

Q2. Can you outline a PTE plan and place from memory the symbols of the first 18 elements and of the remaining alkali metals, halogens, and inert elements?

Q3. Consult the melting and boiling points of the alkali metals in a table. Compare these sequences, vs. the atomic number, with the corresponding ones to halogens and inert elements. Can you suggest an explanation?

Q4. Can you give the names and formulae of four Na compounds?

Etcetera: There is a need to develop PTE research to understand periodic properties and periodic law (PL). The PTE is empirical: more important than nomenclature are the facts of chemical behavior depending on the outer-core shells and frontier orbitals. Nowadays, the most striking points of PTE continue to be: (1) the elements that occupy the same column present similar chemical properties; (2) the opposed behavior between both extreme groups (alkaline elements, halogens).

In this group, Valero-Molina reported PTE and its relationship with daily life [1]. Earlier publications presented empirical didactics [2-4], resonance in interacting induced-dipole polarizing force fields [5], its implementation in chemical education [6], tool for macromolecular- structure interrogation/retrieval [7], reflections on the cultural history of nanominiaturization and quantum simulators (computers) [8], and the nature of PTE [9-13].

GROUPS IN THE PERIODIC TABLE OF THE ELEMENTS (PTE)

Table 6.1 shows the groups in the PTE.

TABLE 6.1 Groups in the Periodic Table of the Elements

WORKING GUIDE

Casanova Freixas and del Barrio Estevez raised questions providing answers [14, 15]. We plan activities, neither objectives nor contents to help teachers stimulate inquiiy-based learning. We propose thinking and answering individually the following questions. Pending problems can be worked in groups.

Ql. Do all electrons in an atom occupy the ls-orbital, which has the least energy?

A1. Pauli exclusion principle. No, the maximum number of electrons that can occupy the same orbital is two.

Q2. A gas mass formed by H atoms, would be an element?

A2. Yes, but such an elementary form based on monoatomic H is difficult to observe as is in the Earth. For people, H is a molecular gas of formula H,.

Q3. What are two gaseous allotropic forms of О molecules?

A3. The О is O, but it also exists ozone О . The O, and O, are allotropic forms of O.

Q4. What is the difference between water and a mixture of H, and O,?

A4. In water, there are only triatomic molecules H-O-H. In H,/6, mixture, molecules H-H and 0-0 exist.

Q5. What is the deprotonation in water of a weak acid, e.g., HF?

A5. HF + H,0OF- + H₃0-.

Q6. Without looking at PTE but reminding the number of elements in every row (2, 8, 8, 18, 18, 32, 32), which elements have the atomic numbers 9, 10, 11, 17, 19, 35, 37 and 54 [16]?

Q7. Can you outline a PTE plan and place from memory the symbols of the first 18 elements and of the remaining alkali metals, halogens, and inert elements?

Q8. Consult the melting and boiling points of the alkali metals in a table. Compare these sequences, vs. the atomic number, with the corresponding ones to halogens and inert elements. Can you suggest an explanation?

Q9. Can you give the names and formulae of four Na compounds?

Q10. Can you compare the properties of HC1 and NaCl?

Qll. What would be observed if a solution containing a great amount of KI be shaken with a small quantity of Cl_2(g)?

Q12. Remembering that in the ordinary chemical reactions the atoms are neither created nor destroyed, can you write the adjusted equations for the following reactions: a) hydrogen and oxygen (O,), to form water; b) sulfuric acid (H₂S0₄) and magnesium, to form hydrogen and magnesium sulfate (MgS0₄); c) reduction of cupric oxide (CuO), with hydrogen, to form copper and water; d) hydrogen release by reaction of potassium with water; e) reaction of carbon dioxide (CO,) with potassium hydroxide, to form potassium carbonate; f) reaction of fluorhydric acid with silica (SiO,), to form silicon tetrafluoride (SiF₄); g) copper burning in fluorine, to form cupric fluoride (CuF,); h) reaction of sodium hydroxide with chlorhydric acid, to form kitchen salt; i) reaction of sodium bromide with sulfuric acid, to form hydrogen bromide; j) carbon-dioxide release from sodium hydrogen carbonate with sulfuric acid?

Q13. From their places in PTE, can you predict some properties of At and Fr?

Q14. What are allotropic forms? What differences can be mentioned between the properties and structure of O, and 0₃?

Q15. Are other elements known, in addition to О and C, which exist in allotropic forms?

Q16. What are the names and chemical formulae of the substances with the following common names: lampblack, quartz, borax, magnesia, limestone, quicklime, slaked lime, gypsum, plaster, barite, emery, ruby, sapphire, and alum?

Q17. Read the list of the names of all the elements. How many are heard about in the ordinary life, apart from the chemistry lessons? Make a list of 10 of the least common elements, and write a sentence establishing some fact on its basis, learned in the ordinary life.

Q18. Make a list of all the generalizations about the variation of the physical and chemical properties with regard to the position in PTE, which could be discovered. During the study of chemistry, remember the generalizations; check these, as well as new ones that could be discovered, in the light of every new studied chemical fact; e.g., What regularity is there in the formulae of the hydrides of group V? Compare with the formulae of the main acids of the elements of group V. Friedel and Maloney raised the following Qs on the subscript in a chemical formula [17].

Q19. How many oxygen atoms are present in a container with 288 g of

o₃?

Datum: molar mass of 0₃ is 48.0 g.

Q20. There are 1.8><10⁵ atoms in a sample of P₄. What is the mass of this sample?

Datum: molar mass of P₄ is 124 g.

Q21. How many atoms of sulfur are in a sample of 963 g of S₆?

Datum: gram atomic weight of S is 32.1 g.

Q22. There are 2.41 xio²⁴ atoms in a sample of S_s. What is the mass of this sample?

Datum: gram atomic weight of S is 32.1 g.

Cervellini et al. raised the following questions [18].

Q23. How do you classify the elements in accordance with their physical and chemical properties?

Q24. Which are the periodic properties?

Q25. Can metallic character be verified in the practical laboratory work?