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Introduction
Published in Yip-Wah Chung, Monica Kapoor, Introduction to Materials Science and Engineering, 2022
Generally, electronegativity increases as we go across the row of the periodic table from left to right and decreases as we go down the column. Among all naturally occurring elements, the most electronegative elements are fluorine (3.98), oxygen (3.44), chlorine (3.16), and nitrogen (3.04), while the most electropositive elements are francium (0.70), cesium (0.79), rubidium (0.82), and potassium (0.82).
Introduction
Published in Armen S. Casparian, Gergely Sirokman, Ann O. Omollo, Rapid Review of Chemistry for the Life Sciences and Engineering, 2021
Armen S. Casparian, Gergely Sirokman, Ann O. Omollo
Electronegativity: Electronegativity is the ability of an atom in covalently bonded molecule to attract electrons to itself. It is the atom’s pulling power to attract electrons to itself. The difference in pulling power or attracting electrons between the two atoms in a molecule is what determines its charge distribution and polarity. The scale of electronegativities runs from 0.0 to 4.0. Cesium and francium are alkali metals and have the lowest electronegativity values (often <1), while fluorine has the highest (3.98) followed by oxygen (3.44) and chlorine (3.16). The greater the difference in electronegativity values between two atoms bonded in a molecule, the greater the degree of polarity. All three of these quantities play a role in determining bond length, bond energy, and many other chemical and physical properties, and ultimately chemical reactivity.
Orbitals and Bonding
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
Electronegativity is a measure of the attraction that an atom has for the bonding pair of electrons in a covalent bond. A more electronegative atom will attract more electron density toward itself than a less electronegative atom. What is a polar covalent bond?
Experimental study on water-based drilling fluid for horizontal wells
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Zhaohui Wei, Yichao He, Sui Gu, Yanping Shi, Xianyu Yang, Jihua Cai
Among the surfactant combinations, the fluorocarbon surfactant FC-1 played the key role. The fluorine atom has the strongest electronegativity of all elements (electronegativity is 4.0) and the lowest atomic polarizability (polarizability is only 0.56). The fluorocarbon bond energy (485.6 KJ/mo1) is higher than the hydrocarbon bond energy (413 KJ/mol). A less polar fluorocarbon chain has a more hydrophobic interaction than the hydrocarbon chain. The fluorocarbon chain is easier to form a well-arranged and stable hydrophobic layer on the surface of shale (Li et al. 2017; Qin and Liu 2008). The stronger a shale is hydrophobic, the smaller the area of shale in contact with moisture (Yue et al. 2018). If the shale hydration is weaker, the speed and extent of shale pore-pressure transmission will be inhibited to some extent. Besides, the combination with PTEE-1 and OS-1 not only had the strongest hydrophobicity (contact angle of 100.7°), but also had the best effect to slowdown pore-pressure transmission rate in the Shuijingtuo shale.
Strategies for ultrahigh outputs generation in triboelectric energy harvesting technologies: from fundamentals to devices
Published in Science and Technology of Advanced Materials, 2019
At the beginning of the research, most researchers focused on the electronegativity of polymers because it was deeply related with charge-neutrality level. Electronegativity refers to the ability of an atom to attract the electrons shared by atoms in a covalent bond. The higher the value of the electronegativity, the more strongly the atom attracts the electrons. Fluoro group (-F) has the highest tendency to attract electrons, thus, various polymers with the fluoro group such as PTFE, FEP and polyvinylidene fluoride (PVDF) were tested and quite high instantaneous outputs were reported in various-type TENGs [45,49,50]. Recently, the surface of PDMS in an arch-shaped TENG was modified via fluorocarbon (C4F8) plasma treatment (Figure 3(a,b)), the TENG output peak voltage increased sharply from 124 V to 265 V after eight-cycle plasma treatment (Figure 3(c)). The energy volume density of TENG was enhanced by approximately 278%, compared with the TENG fabricated with pristine PDMS layer. The enhancement of the outputs was attributed to the increase of the ionization energy by fluorination and the formation of PDMS micro/nano hierarchical structures by the treatment (Figure 3(d,e)).
Structural modification of aluminum oxides for removing fluoride in water: crystal forms and metal ion doping
Published in Environmental Technology, 2022
Guomin Jiang, Linfeng Jin, Qinglin Pan, Ning Peng, Yun Meng, Lei Huang, Haiying Wang
More importantly, the adsorption capacity of the M-Al2O3 increased as the electronegativity of the doped metals decreased. Fluoride has the highest electronegativity among all elements (3.98) and a small atomic radius. It is considered a ‘hard base’, which can easily to combine with ‘hard acid’ metals (e.g. Al3+, Ca2+) with low electronegativity [48]. The strength of the bonding between ions increases as the difference in their electronegativity increases. La had a high affinity for fluoride because of its relatively low electronegativity. As a result, La-Al2O3 had the highest fluoride removal performance.