Structure of Periodic Table

10 Key excerpts on "Structure of Periodic Table"

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  eBook - ePub

  General Chemistry for Engineers

  • Jeffrey Gaffney, Nancy Marley(Authors)
  • 2017(Publication Date)
  • Elsevier

    (Publisher)

  Chapter 2

  The Periodic Table of the Elements

  Abstract

  This chapter covers the names and symbols of the elements. The basic structure of the atom is reviewed including an explanation of isotopes. A discussion of the shell model of the atom describes electronic shells, subshells, their quantum numbers, orbital shapes, electron filling order, and the determination of the complete electron configuration of the elements. The development of the Periodic Table of the Elements and Periodic Law is described from a historical point of view followed by a general description of the modern periodic table. As valence electrons control the chemistry of the elements, particular emphasis is given to the use of the periodic table to predict the valence electron configurations and so to predict the chemical properties of the elements. The periodic trends in atomic radius, ionization energy, electron affinity, electronegativity, and metallic properties are described and explained according to the position of the elements in the periodic table.

  Keywords

  Atomic structure; Subatomic particles; Atomic mass; Isotopes; Electronic configuration; Quantum numbers; Orbital shapes; Periodic table; Valence electrons; Periodic trends

  Chapter Outline

  2.1  

  Atomic Structure

  2.2  

  The Shell Model of the Atom

  2.3  

  Electron Assignments

  2.4  

  The Periodic Table of the Elements

  2.5  

  Periodic Trends

  Important Terms

  Study Questions

  Problems

  2.1 Atomic Structure

  As we saw in Chapter 1 , chemists have over the years identified the 98 naturally occurring elements that make up all of the molecules and materials that we find on our planet. Each of these elements is defined by its distinctive chemical and physical properties, which set it apart from all the other elements. Each element was named as it was discovered. Some of the names of the elements were derived from their observed properties or their method of discovery. For example, the element hydrogen was discovered by Henry Cavendish in 1766. He noted that it generated water when reacted with oxygen and named it from the Greek words for water (hydros ) and generator (genes ). Helium was named from the Greek word for sun (Helios ) as it was originally discovered in 1895 through studies of the solar emission spectrum. Other elements were named for their discoverers or their place of discovery. Europium, discovered by a French chemist Eugène-Anatole Demarcay in 1896, was named for the European continent where it was discovered while americium was named for America, the continent where it was discovered. Similar histories can be found for all of the elements. Only one element has been named for a chemist while he was still alive. This element is Seaborgium, named for Dr. Glenn Seaborg who led the discovery of a number of short-lived elements that were artificially generated using nuclear reactions at the University of California, Berkeley. We will discuss these elements and their radioactivity in Chapter 14

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  Foundations of College Chemistry

  • Morris Hein, Susan Arena, Cary Willard(Authors)
  • 2021(Publication Date)
  • Wiley

    (Publisher)

  We have seen how the electrons are assigned for the atoms of elements 1–18. How do the electron structures of these atoms relate to their position on the periodic table? To answer this question, we need to look at the periodic table more closely. 218 CHAPTER 10 Modern Atomic Theory and the Periodic Table The periodic table represents the efforts of chemists to organize the elements logically. Chemists of the early nineteenth century had sufficient knowledge of the properties of ele- ments to recognize similarities among groups of elements. In 1869, Dimitri Mendeleev (1834– 1907) of Russia and Lothar Meyer (1830–1895) of Germany independently published periodic arrangements of the elements based on increasing atomic masses. Mendeleev’s arrangement is the precursor to the modern periodic table, and his name is associated with it. The modern periodic table is shown on the inside front cover of this book. Each horizontal row in the periodic table is called a period, as shown in Figure 10.14. There are seven periods of elements. The number of each period corresponds to the outermost 1 2 3 4 5 6 7 Period 3B 4B 5B 6B 7B 8B 1B 2B 3A 4A 5A 6A 7A 1 2 3 4 5 6 7 11 12 13 14 15 16 17 Group number Atomic number Symbol 36 Kr 18 Ar 10 Ne He 54 Xe 86 Rn 118 Og 35 Br 17 Cl 9 F 53 I 85 At 117 Ts 32 Ge 14 Si 6 C 50 Sn 82 Pb 33 As 15 51 Sb 83 Bi 34 Se 16 S 8 O 52 Te 84 Po 114 Fl 115 Mc 116 Lv 30 Zn 48 Cd 80 Hg 31 Ga 13 Al 5 B 49 In 81 Tl 112 Cn 113 Nh 19 20 21 22 23 24 25 26 27 28 29 K 37 Ca 38 Sc 39 Ti 40 V 41 Cr 42 Mn 43 Fe 44 Co 45 Ni 46 Cu 47 Rb 55 Cs Sr 56 Ba Y 57–71 La–Lu Zr 72 Hf Nb 73 Ta Mo 74 W Tc 75 Re Ru 76 Os Rh 77 Ir Pd 78 Pt Ag 79 Au 87 Fr 88 Ra 89–103 Ac–Lr 104 Rf 105 Db 106 Sg 107 Bh 108 Hs 109 Mt 110 Ds 111 Rg H Li 11 Na 4 Be 12 Mg P 7 N 1A 2A 9 F 2 1 3 8 9 10 Noble gases 18 8A FIGURE 10.14 The periodic table of the elements. Chemistry in Action Collecting the Elements Theodore Gray loves collecting samples of elements.

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  Collected Papers On The Philosophy Of Chemistry

  • Eric R Scerri(Author)
  • 2008(Publication Date)
  • ICP

    (Publisher)

  Section B The Periodic Table, Electronic Configurations and the Nature of the Elements This page intentionally left blank This page intentionally left blank ERIC R. SCERRI HAS THE PERIODIC TABLE BEEN SUCCESSFULLY AXTOMATIZED? ABSTRACT. Although the periodic system of elements is central to the study of chemistry and has been influential in the development of quantum theory and quantum mechanics, its study has been largely neglected in philosophy of science. The present article is a detailed criticism of one notable exception, an attempt by Hettema and Kuipers to axiomatize the periodic table and to discuss the reduction of chemistry in this context. 1. HISTORICAL PRELUDE AND THE TREATMENT OF THE PERIODIC SYSTEM AND TABLE IN THE PHILOSOPHICAL LITERATURE The Periodic Table of the elements has had a profound influence on the development of modem chemistry and physics. In chemistry its influence is well known and undeniable. The periodic system functions as a unifying principle which continues to guide the day-to-day research of chemists in many specialized areas. The influence of the periodic table on the develop- ment of physics and in particular quantum mechanics is not so well known but equally undeniable. Shortly after the turn of the century, J. J. Thomson, the discoverer of the electron, regarded the question of trying to explain the periodic table through atomic physics as one of the major unsolved problems. In 1904 he tried to account for the periodicity of the elements in terms of the arrangement of electrons in rings. Thomson proposed a detailed set of atomic configurations as part of his plumb pudding model in which electrons were embedded in the main body of the atoms and were held to circulate in concentric rings (Thomson, 1904).

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  Chemistry

  Principles and Reactions

  • William Masterton, Cecile Hurley(Authors)
  • 2020(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 148 CHAPTER 6 Electronic Structure and the Periodic Table ▼ SOLUTION Fe electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 Cation with 1 2 charge subtract 2 electrons Highest n 4 with only one sublevel Fe 2 1 electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 2 2 3d 6 5 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 Br electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 Anion with 2 1 charge add 1 electron Highest n 4 with 2 sublevels (s and p) Highest ø in n p Br 2 electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 1 1 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 END POINT The electron configuration for Br 2 is the same as that for the noble gas closest to it, krypton. 6-8 Periodic Trends in the Properties of Atoms One of the most fundamental principles of chemistry is the periodic law, which states that The chemical and physical properties of elements are a periodic function of atomic number. This is, of course, the principle behind the structure of the periodic table. Elements within a given vertical group resemble one another chemically because chemical properties repeat themselves at regular intervals of 2, 8, 18, or 32 elements. In this section we will consider how the periodic table can be used to correlate properties on an atomic scale. In particular, we will see how atomic radius, ionic radius, ionization energy, and electronegativity vary horizontally and vertically in the periodic table. Atomic Radius Strictly speaking, the “size” of an atom is a rather nebulous concept. The electron cloud surrounding the nucleus does not have a sharp boundary.

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  Chemistry: Atoms First

  • William R. Robinson, Edward J. Neth, Paul Flowers, Klaus Theopold, Richard Langley(Authors)
  • 2016(Publication Date)
  • Openstax

    (Publisher)

  There is no simple method to predict the exceptions for atoms where the magnitude of the repulsions between electrons is greater than the small differences in energy between subshells. Electron Configurations and the Periodic Table As described earlier, the periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their electron configurations are added to the table (Figure 3.30), we also see a periodic recurrence of similar electron configurations in the outer shells of these elements. Because they are in the outer shells of an atom, valence electrons play the most important role in chemical reactions. The outer electrons have the highest energy of the electrons in an atom and are more easily lost or shared than the core electrons. Valence electrons are also the determining factor in some physical properties of the elements. Elements in any one group (or column) have the same number of valence electrons; the alkali metals lithium and sodium each have only one valence electron, the alkaline earth metals beryllium and magnesium each have two, and the halogens fluorine and chlorine each have seven valence electrons. The similarity in chemical properties among Chapter 3 | Electronic Structure and Periodic Properties of Elements 155 elements of the same group occurs because they have the same number of valence electrons. It is the loss, gain, or sharing of valence electrons that defines how elements react. It is important to remember that the periodic table was developed on the basis of the chemical behavior of the elements, well before any idea of their atomic structure was available. Now we can understand why the periodic table has the arrangement it has—the arrangement puts elements whose atoms have the same number of valence electrons in the same group.

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  Foundations of College Chemistry

  • Morris Hein, Susan Arena, Cary Willard(Authors)
  • 2016(Publication Date)
  • Wiley

    (Publisher)

  In Period 3, electrons are found in levels 1, 2, 3, and so on. Elements that behave in a similar manner are found in groups or families. These form the vertical columns on the periodic table. Two systems exist for numbering the groups. In one system, the columns are numbered from left to right using the numbers 1–18. The A groups are known as the representative elements. The B groups are called the transition elements. In this book we will focus on the representative elements. The groups (columns) of the periodic table often have family names. For example, the group on the far right side of the periodic table (He, Ne, Ar, Kr, Xe, and Rn) is called the noble gases. Group 1A(1) is called the alkali metals, Group 2A(2) the alkaline earth metals, and Group 7A(17) the halogens. How is the structure of the periodic table related to the atomic structures of the elements? We’ve just seen that the periods of the periodic table are associated with the energy level of the outermost electrons of the atoms in that period. Look at the valence electron configurations of the elements we have just examined (FIGURE 10.15). Do you see a pattern? The valence electron configuration for the elements in each column is the same. The chemical behavior and properties of elements in a particular family must therefore be associated with the electron configuration of the elements. The number for the principal energy level is different. This is expected since each new period is associ- ated with a different energy level for the valence electrons. The electron configurations for elements beyond these first 18 become long and tedious to write. We often abbreviate the electron configuration using the following notation: Na [Ne]3s 1 Look carefully at Figure 10.15 and you will see that the p orbitals are full at the noble gases.

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  Chemistry for Today

  General, Organic, and Biochemistry

  • Spencer Seager, Michael Slabaugh, Maren Hansen, , Spencer Seager, Spencer Seager, Michael Slabaugh, Maren Hansen(Authors)
  • 2021(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Scientists looked for order in these facts, with the hope of providing a systematic approach to the study of chemistry. Two scientists independently, and almost simultaneously, made the same important contribution to this end. Julius Lothar Meyer, a German, and Dimitri Mendeleev (see Figure 3.1), a Russian, each produced classification schemes separately for the elements in 1869. Both schemes were based on the periodic law, which in its present form is stated as follows: When all the elements are arranged in order of increasing atomic numbers, elements with similar chemical properties will occur at regular (periodic) intervals. A convenient way to compactly represent such behavior is to use tables. The arrange- ment of the elements in a table based on the periodic law is called a periodic table. In modern periodic table, such as the one inside the front cover of this book, elements with similar chemical properties are found in vertical columns called groups or families. In this book, the groups are designated in two ways. In the U.S. system, a Roman numeral and letter, such as IIA, is used. In the International Union of Pure and Applied Chemistry sys- tem, a simple number, such as 2, is used. Both designations appear on the periodic table inside the front cover of this book, with the IUPAC number in parentheses. We will generally refer to groups in the text by using both the U.S. system and the IUPAC system. Thus, a reference to the second group would be given as group IIA(2), where we have put the IUPAC number in parentheses. The horizontal rows in the table are called periods and are numbered from top to bottom. Thus, each element belongs to both a period and a group of the periodic table. periodic law A statement about the behavior of the elements when they are arranged in a specific order.

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  Chemistry 2e

  • Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
  • 2019(Publication Date)
  • Openstax

    (Publisher)

  However, there are also other patterns in chemical properties on the periodic table. For example, as we move down a group, the metallic character of the atoms increases. Oxygen, at the top of group 16 (6A), is a colorless gas; in the middle of the group, selenium is a semiconducting solid; and, toward the bottom, polonium is a silver-grey solid that conducts electricity. As we go across a period from left to right, we add a proton to the nucleus and an electron to the valence shell with each successive element. As we go down the elements in a group, the number of electrons in the valence shell remains constant, but the principal quantum number increases by one each time. An understanding of the electronic structure of the elements allows us to examine some of the properties that govern their chemical behavior. These properties vary periodically as the electronic structure of the elements changes. They are (1) size (radius) of atoms and ions, (2) ionization energies, and (3) electron affinities. LINK TO LEARNING Explore visualizations (http://openstax.org/l/16pertrends) of the periodic trends discussed in this section (and many more trends). With just a few clicks, you can create three-dimensional versions of the periodic table showing atomic size or graphs of ionization energies from all measured elements. 6.5 • Periodic Variations in Element Properties 295 Variation in Covalent Radius The quantum mechanical picture makes it difficult to establish a definite size of an atom. However, there are several practical ways to define the radius of atoms and, thus, to determine their relative sizes that give roughly similar values. We will use the covalent radius ( Figure 6.30), which is defined as one-half the distance between the nuclei of two identical atoms when they are joined by a covalent bond (this measurement is possible because atoms within molecules still retain much of their atomic identity).

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  Chemistry

  An Atoms First Approach

  • Steven Zumdahl, Susan Zumdahl, Donald J. DeCoste, , Steven Zumdahl, Steven Zumdahl, Susan Zumdahl, Donald J. DeCoste(Authors)
  • 2020(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  It is the number and type of valence electrons that primarily determine an atom’s chemistry. 2. One of the most valuable types of information available from the periodic table is the electron configuration of any representative element. If you understand the organization of the table, you will not need to memorize electron configura- tions for these elements. Although the predicted electron configurations for transition metals are sometimes incorrect, this is not a serious problem. You should, however, memorize the configurations of two exceptions, chromium and copper, since these 3d transition elements are found in many important compounds. 3. Certain groups in the periodic table have special names. These are summarized in Fig. 2.34. Groups are often referred to by these names, so you should learn them. INTERACTIVE EXAMPLE 2.10 92 CHAPTER 2 Atomic Structure and Periodicity Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 4. The most basic division of the elements in the periodic table is into metals and nonmetals. The most important chemical property of a metal atom is the ten- dency to give up one or more electrons to form a positive ion; metals tend to have low ionization energies. The metallic elements are found on the left side of the table, as shown in Fig. 2.34 . The most chemically reactive metals are found on the lower-left portion of the table, where the ionization energies are smallest. The most distinctive chemical property of a nonmetal atom is the ability to gain one or more electrons to form an anion when reacting with a metal.

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  Chemistry: Atoms First 2e

  • Edward J. Neth, Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
  • 2019(Publication Date)
  • Openstax

    (Publisher)

  The discoveries of gallium (1875) and germanium (1886) provided great support for Mendeleev’s work. Although Mendeleev and Meyer had a long dispute over priority, Mendeleev’s contributions to the development of the periodic table are now more widely recognized ( Figure 3.36). FIGURE 3.36 (a) Dimitri Mendeleev is widely credited with creating (b) the first periodic table of the elements. (credit a: modification of work by Serge Lachinov; credit b: modification of work by “Den fjättrade ankan”/Wikimedia Commons) By the twentieth century, it became apparent that the periodic relationship involved atomic numbers rather than atomic masses. The modern statement of this relationship, the periodic law, is as follows: the properties of the elements are periodic functions of their atomic numbers. A modern periodic table arranges the elements in increasing order of their atomic numbers and groups atoms with similar properties in the same vertical column ( Figure 3.37). Each box represents an element and contains its atomic number, symbol, average atomic mass, and (sometimes) name. The elements are arranged in seven horizontal rows, called periods or series, and 18 vertical columns, called groups. Groups are labeled at the top of each column. In the United States, the labels traditionally were numerals with capital letters. However, IUPAC recommends that the numbers 1 through 18 be used, and these labels are more common. For the table to fit on a single page, parts of two of the rows, a total of 14 columns, are usually written below the main body of the table. 150 3 • Electronic Structure and Periodic Properties of Elements Access for free at openstax.org FIGURE 3.37 Elements in the periodic table are organized according to their properties. Even after the periodic nature of elements and the table itself were widely accepted, gaps remained. Mendeleev had predicted, and others including Henry Moseley had later confirmed, that there should be elements below Manganese in Group 7.

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