Chemistry
Prediction of Element Properties Based on Periodic Trends
The prediction of element properties based on periodic trends involves using the periodic table to anticipate the behavior and characteristics of elements. This is done by recognizing patterns in the periodic table, such as atomic size, ionization energy, and electronegativity, which can help predict how elements will interact with other substances and their physical and chemical properties.
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eBook - PDFChemistry 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)
The trends in these properties occur in a regular way that would allow us to predict some of them for one element if they were known for the other elements in the group. For example, if the properties of bismuth were unknown, we would have predicted that it would have a silvery white color and a metallic luster based on the appearance of arsenic and antimony. The three elements from group VIIA(17) shown in Figure 3.18 also dem- onstrate some obvious predictable trends in physical properties. Copyright 2022 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. 88 Chapter 3 Trends in properties occur in elements that form periods across the periodic table as well as among those that form vertical groups. We will discuss two of these properties and their trends for representative elements. Our focus will be on the general trends, rec- ognizing that some elements show deviations from these general behaviors. We will also propose explanations for the trends based on the electronic structure of atoms discussed in the chapter. The first property we will consider is the size of the atoms of the representative elements. The size of an atom is considered to be the radius of a sphere extending from the center of the nucleus of the atom to the location of the outermost electrons around the nucleus. The behavior of this property across a period and down a group is shown in Figure 3.19. We see that the size increases from the top to the bottom of each group, and decreases from left to right across a period.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
Similarly, a group will also see a top to bottom decrease in electronegativity due to an increasing distance between valence electrons and the nucleus. Trends of periods Periodic trend for ionization energy. Each period begins at a minimum for the alkali metals, and ends at a maximum for the noble gases. Elements in the same period show trends in atomic radius, ionization energy, electron affinity, and electronegativity. Moving left to right across a period, atomic radius usually decreases. This occurs because each successive element has an added proton and electron which causes the electron to be drawn closer to the nucleus. This decrease in atomic radius also causes the ionization energy to increase when moving from left to right across a period. The more tightly bound an element is, the more energy is required to remove an electron. Similarly, electronegativity will increase in the same manner as ionization energy because of the amount of pull that is exerted on the electrons by the nucleus. Electron affinity also shows a slight trend across a period. Metals (left side of a period) ________________________ WORLD TECHNOLOGIES ________________________ generally have a lower electron affinity than nonmetals (right side of a period) with the exception of the noble gases. History The history of the periodic table reflects over a century of growth in the understanding of chemical properties, and culminates with the publication of the first actual periodic table by Dmitri Mendeleev in 1869. While Mendeleev built upon earlier discoveries by such scientists as Antoine-Laurent de Lavoisier, the Russian scientist is generally given sole credit for development of the actual periodic table itself. The table itself is a visual representation of the periodic law which states that certain properties of elements repeat periodically when arranged by atomic number.
eBook - ePub- Léna Soler, Sjoerd Zwart, Michael Lynch, Vincent Israel-Jost, Léna Soler, Sjoerd Zwart, Michael Lynch, Vincent Israel-Jost(Authors)
- 2014(Publication Date)
- Taylor & Francis(Publisher)
The simultaneous presentation of many such relations facilitates the recognition of higher-order patterns. Categories such as “halide” and “transition metal” emerge and trends in electronegativity, ionization energy, and oxidation states can be rationalized, in part because they become readily identifiable. Patterns of atomic volumes and ionic radii become conspicuous and consequently make a multitude of facts concerning chemical bonding and reactivity comprehensible and predictable (see Figure 4.5). Figure 4.5 Trends for some chemical and physical properties of the elements as organized by the modern periodic table The periodic table’s ability to guide reasoning, and inquiry more generally, flows from this particular way of aggressively projecting order onto its complicated domain. The nature of this guidance is suggestive, however, rather than explicitly inferential. The periodic table displays patterns and implicitly represents them to be far-reaching and robust. The prediction of a new element, for instance, follows from recognition that something is absent from the imposed structure. The table reveals a “hole” and insinuates that something is missing. But there is no formal structure to generate quantitatively precise predictions. It is also significant that much of the reasoning supported by the periodic table is analogical. A category such as “halide” is important within the practice precisely because it allows us to reason, “If compound X displays certain properties, then the related compound Y will display analogous properties”. In a domain such as descriptive chemistry, analogical reasoning is an important tool for gaining control over complexity; a multitude of facts can be managed if they fall into conspicuous patterns rather than remain independent and singular. As I have argued, a tabular format, in particular, carves out such patterns
- Martha Mackin(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
FIVE The periodic table OVERVIEW This chapter gives the history of the development of the periodic table. The properties of the elements are repeated in a regular way, so the elements can be arranged into a periodic table. The horizontal rows in the table are called periods; the vertical columns are called groups. Chapter 4 described how the electronic structure of atoms varies in a regular way with atomic number. This chapter shows the relationship between the periodic repetition of the properties of the elements and the periodic repetition of electronic structure. Each group in the periodic table has similar properties and similar arrangement of outer electrons. Each period is related to the filling of one or more energy levels. Elements may be identified as metals, nonmetals, semimetals, transition elements, inner tran-sition elements, or noble gases by their position in the periodic table. The properties of the elements within a group are similar but vary from each other in a regular way. The properties of elements in a period are different but each period shows similar changes in properties of the elements from left to right in the periodic table. These periodic varia-tions in properties are related to periodic changes in the structure of the atoms. Atomic size increases down a group and decreases from left to right across a period; Ionization potential and electron affinity decrease down a group and increase across a period. Metallic properties are related to low ionization potential, low electron affinity and large atomic size. Nonmetallic properties are related to high ionization potential, high electron affinity and small atomic size. Other periodic arrangements of the elements are described and illustrated. A brief survey of elements by periodic group is included.
eBook - PDFEngineering Chemistry
Fundamentals and Applications
- Shikha Agarwal(Author)
- 2019(Publication Date)
- Cambridge University Press(Publisher)
8.1 Introduction The genesis of classification of elements dates back to early 1800s when the German chemist Johann Dobereiner made the first attempt to systematise the study of properties of elements and gave the Dobereiners law of triads. This was followed by the Newlands law of octaves. The first detailed classification of elements was proposed by Russian chemist Dmitri Mendeleev (1837–1907) and German chemist Lothar Meyer (1830–1895). Both these scientists worked independently and in 1869 proposed that when elements are arranged in the increasing order of their atomic weights, similarities appear in their physical and chemical properties at regular intervals. However, the Mendeleev’s periodic table had certain anomalies, which were addressed in due course of time. Gradual improvement saw the development of the modern periodic law (given by Henry Moseley) in which the elements are arranged in the order of increasing atomic numbers. The elements are arranged in the periodic table in the order of increasing atomic numbers. They are divided into 18 vertical columns called groups and seven horizontal rows termed as periods. According to the IUPAC recommendations, the groups are numbered from 1 to 18, replacing the older notations of groups IA…VIIA, IB…VIIB and zero. The seven periods have 2, 8, 8, 18, 18 and 32 elements, respectively. The seventh period is incomplete and will theoretically consist of 32 elements. The properties of the elements vary periodically due to periodic variation in their electronic configuration. In this chapter, we will study the variations in electronic configurations, atomic and ionic sizes, ionisation energies and other related properties. 8.2 Basic Concepts Before studying the periodicity in properties of elements, it is important to have knowledge of some basic terms and concepts.
eBook - PDF- C N R Rao(Author)
- 2009(Publication Date)
- World Scientific(Publisher)
• have similar properties. • become more metallic in character down the group. In water solution, most ions of transition elements are coloured. Some of these elements exhibit more than one valency (Fe 2+ , Fe 3+ ; Mn 2+ , Mn 3+ , Mn 4+ ,…, Mn 7+ ). Some of the metals and their ions have catalytic properties. Iron, cobalt and nickel are magnetic. These are permanent magnets ( ferromagnetic ). Compounds of these and many other transition elements are attracted by a magnet. They are paramagnetic . Sc scandium Ti titanium V vanadium Cr chromium Mn manganese Fe iron Co cobalt Ni nickel Cu copper Zn zinc Properties of an element in a group can be predicted on the basis of the properties of another element in the same group. Elements and the periodic table 119 Periodicity in the modern periodic table is a function of the electronic configuration. 2.5 Periodic table and properties of elements Physical properties: • Melting point, boiling point and density of elements increase across a period until maximum values are reached. Then they decrease. Noble gases have low values. • Elements become less metallic across a period and more metallic down a group. • The atomic size and ionic size decrease across a period and increase down a group. Physical properties Electronegative and electropositive nature Redox properties Properties of compounds There is PERIODICITY of 120 Understanding Chemistry Electron affinities of a few elements (in electron volts) are given below: F 3.40 I 3.06 Cl 3.61 H 0.75 Br 3.36 O 1.46 H 13.6 C 11.3 Na 5.1 He 24.6 N 14.5 Mg 7.6 Li 5.4 O 13.6 Cl 13.0 Be 9.3 F 17.4 K 4.3 B 8.3 Ne 21.6 Rb 4.2 Electron affinity is the energy change that occurs when an atom accepts an electron. Atoms with high electron affinity readily become negative ions.
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