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editLead: Discovery of Periodic Trends
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editIn chemistry, periodic trends are specific patterns present in the periodic table that illustrate different aspects of certain elements when grouped by period and/or group. They were discovered by the Russian chemist Dmitri Mendeleev in 1863. Major periodic trends include atomic radius, ionization energy, electron affinity, electronegativity, valency and metallic character. Mendeleev built the foundation of the periodic table.[1] Mendeleev organized the elements based on atomic weight, leaving empty spaces where he believed undiscovered elements would take their places.[2][3] Mendeleev’s discovery of this trend allowed him to predict the existence and properties of three unknown elements, which were later discovered by other chemists and named gallium, scandium, and germanium.[3] English physicist Henry Moseley discovered that organizing the elements by atomic number instead of atomic weight would naturally group elements with similar properties.[2]
Lead: Nucleophilicity and Electrophilicity
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editElectrophilicity is defined as an electron-deficient species, an electrophile, and its affinity for accepting electrons.[4] Nucleophilicity is defined as an electron-rich species, a nucleophile, and its affinity to donate electrons to another species [5] The periodic table has applicable trends to determine an element's nucleophilicity and electrophilicity. Nucleophilicity increases as electronegativity increases, therefore, nucleophilicity increases left-to-right on the periodic table. [6]Electronegativity increases as electronegativity decreases, therefore, electronegativity decreases left-to-right on the periodic table. [6]
Lead: Electron Affinity
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editThe energy released when an electron is added to a neutral gaseous atom to form an anion is known as electron affinity.[7] Trend-wise, as one progresses from left to right across a period, the electron affinity will increase as the nuclear charge increases and the atomic size decreases resulting in a more potent force of attraction of the nucleus and the added electron. However, as one moves down in a group, electron affinity decreases. Similarly to ionization energy, this is caused by the increase in atomic size due to the addition of a valence shell, which weakens the nucleus's attraction to electrons. Although it may seem that fluorine should have the greatest electron affinity, its small size generates enough repulsion among the electrons, resulting in chlorine having the highest electron affinity in the halogen family.[8]
Lead: Nuclear Charge
editLead
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editNuclear charge is defined as the number of protons in the nucleus of the relevant element.[9]
Lead: Atomic Radius
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editReferences
edit- Scerri, E. R.; Worrall, J. Prediction and the Periodic Table. Studies in History and Philosophy of Science Part A 2001, 32 (3), 407–452. https://doi.org/10.1016/s0039-3681(01)00023-1.
- An Appraisal of Mendeleev’s Contribution to the Development of the Periodic Table. Studies in History and Philosophy of Science Part A 2004, 35 (2), 271–282. https://doi.org/10.1016/j.shpsa.2003.12.014.
- Uggerud, E. Nucleophilicity—Periodic Trends and Connection to Basicity. Chemistry - A European Journal 2006, 12 (4), 1127–1136. https://doi.org/10.1002/chem.200500639.
- Rahm, M., Erhart, P., & Cammi, R. (2021). Relating atomic energy, radius and electronegativity through compression. Chemical science, 12(7), 2397–2403. https://doi.org/10.1039/d0sc06675c
- Edwards, P. P., Egdell, R. G., Fenske, D., & Yao, B. (2020). The periodic law of the chemical elements: 'The new system of atomic weights which renders evident the analogies which exist between bodies' [1]. Philosophical transactions. Series A, Mathematical, physical, and engineering sciences, 378(2180), 20190537. https://doi.org/10.1098/rsta.2019.0537
- ^ Edwards, Peter P.; Egdell, Russell G.; Fenske, Dieter; Yao, Benzhen (2020-09-18). "The periodic law of the chemical elements: ' The new system of atomic weights which renders evident the analogies which exist between bodies ' []". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 378 (2180): 20190537. doi:10.1098/rsta.2019.0537. ISSN 1364-503X. PMC 7435142. PMID 32811357.
{{cite journal}}: CS1 maint: PMC format (link) - ^ a b Egdell, Russell G.; Bruton, Elizabeth (2020-09-18). "Henry Moseley, X-ray spectroscopy and the periodic table". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 378 (2180): 20190302. doi:10.1098/rsta.2019.0302. ISSN 1364-503X.
- ^ a b Sztejnberg, Aleksander (2018). "Dmitri Ivanovich Mendeleev (1834 – 1907), Prominent Russian Scientist. References to His Great Scientific Achievements in the Literature between 1871 and 1917" (PDF). Revista CENIC. 49 (1) – via Redalyc.
{{cite journal}}: line feed character in|title=at position 42 (help) - ^ Nazmul, Islam; Ghosh, Dulal C (February 17, 2012). "On the Electrophilic Character of Molecules Through Its Relation with Electronegativity and Chemical Hardness". International Journal of Molecular Sciences. 13 (2): 2160-2175. doi:10.3390/ijms13022160. Retrieved November 1, 2024.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Savin, Kenneth A. (2015). Writing Reaction Mechanisms in Organic Chemistry (3 ed.). Academic Press. p. 1-53. Retrieved November 1, 2024.
- ^ a b Department of Research and Publication, Kampala International University, Uganda; Alum, Benedict Nnachi (2024-06-08). "Exploring the Trends and Patterns in Periodicity of Elements: from Mendeleev to Modern Periodic Table". NEWPORT INTERNATIONAL JOURNAL OF SCIENTIFIC AND EXPERIMENTAL SCIENCES. 5 (2): 1–6. doi:10.59298/NIJSES/2024/10.5.26216.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Gooch, Jan W., ed. (2007), "Electron affinity", Encyclopedic Dictionary of Polymers, New York, NY: Springer, p. 350, doi:10.1007/978-0-387-30160-0_4245, ISBN 978-0-387-30160-0, retrieved 2022-07-02
- ^ "Electron Affinity Trend | Science Trends". sciencetrends.com. 2018-05-14. Retrieved 2022-07-02.
- ^ L'Annunziata, Michael F. (2016-01-01), L'Annunziata, Michael F. (ed.), "Chapter 2 - Basic Concepts and Definitions", Radioactivity (Second Edition), Boston: Elsevier, pp. 67–78, doi:10.1016/b978-0-444-63489-4.00002-2, ISBN 978-0-444-63489-4, retrieved 2024-11-04
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