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ELECTRONEGATIVITY

ELECTRONEGATIVITY. Arighno , Pranav , Wes. Definition. Electronegativity describes the ability of an atom to attract electrons to itself in a chemical bond. The values range from 0 and 4 The values are representative of the electronegativity, there are no units.

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ELECTRONEGATIVITY

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  1. ELECTRONEGATIVITY Arighno, Pranav, Wes

  2. Definition • Electronegativity describes the ability of an atom to attract electrons to itself in a chemical bond. • The values range from 0 and 4 • The values are representative of the electronegativity, there are no units. • Fluorine has the highest with 3.98 and Cesium has the lowest with 0.7 • Values are unitless, but sometimes are regarded in Pauling Units, when converting electronegativity values from other methods • Linus Pauling created this scale in 1932

  3. Linus Pauling(1901–1994), the Pauling Scale, and other methods to calculate electronegativity • "It has been found possible to assign to the elements numbers representing their power of attraction for the electrons in a covalent bond, by means of which the amount of partial ionic character may be estimated.“ • Pauling Scale(1932) – Obtains electronegativity values through thermochemical methods. • Mulliken Relation(1934) - The numerical average of the ionisation potential and electron affinity • Allred-Rochow Scale(1958) -Defines electronegativity in terms of the effective nuclear charge and covalent radius

  4. Electronegativity Table

  5. Family Trends and Reasoning • Family Trends: The electronegativity decreases as you descend down a family. • Reasons: As you go down a family, the effective nuclear charge decreases because there are more levels of electrons to shield the nuclear charge. Because of this, the ability of the nucleus to attract electrons is decreased. Additionally, the physical distance between the nucleus and the valence electrons increases, also lowering the effective nuclear charge.

  6. Period Trends and Reasons • Period Trends: As you go across the periodic table, the electronegativity increases. • Reason: As you across a period, the effective nuclear charge increases. This happens because the number of protons in the nucleus increases, but the number of energy levels does not. Therefore, the effective nuclear charge increases as you go across. • Ex: Z* for oxygen is +6 compared to the Z* of boron which is +3. • The valence electrons of Oxygen are attracted to the nucleus as if there were no other inner energy levels and there were 6 protons. Lithium, on the other hand, has valence electrons attracted to the nucleus as if there were only 3 protons.

  7. Exceptions Gallium and Germanium have higher electronegativity values than aluminum and silicon. Elements of the fourth period immediately after the first row of the transition metals have unusually small atomic radii because the 3d-electrons are not effective at shielding the increased nuclear charge. Lead has an unusually high electronegativity value, compared to Thallium and Bismuth. Occurrence of data selection

  8. Determining bond type from electronegativity

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