What explains why electronegativity increases as you move across a period? Does it have something to do with the shielding effect of added electrons?

The electronegativity is the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.

You are watching: Electronegativity increases as the size of the atom increases.

This is because the attraction of bonding electrons by an atom increases with nuclear charge (Atomic Number) and decrease of atomic radius. Both these factors operate as we move to the right in period.

Does it have something to do with the shielding effect of added electrons?

The electron cloud in the inner orbits act as a shield and reduces the nuclear attraction to the outer orbits. Because of the shielding effect, the tendency of nuclear attraction reduces and thus electronegativity reduces.

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answered Nov 25 "13 at 6:15

ashuashu
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ashu"s answer is good, but it does not get to the real reason that electronegativity increases across periods. Electronegativity is dependent on other properties that are more intuitively dependent on position within a period.

The absolute (Mulliken) electronegativity $\chi$ (which correlates with the more familiar, but more abstract, Pauling electronegativity) of an atom is the arithmetic mean of its first ionization energy and its first electron affinity

$$\chi_A = (E_{i,A}+E_{ea,A})/2$$

These values behave in a predictable manner related to the effective nuclear charge idea ashu mentions. Consider the data from the second period (all values in kJ/mol):

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answered Nov 26 "13 at 16:09

Ben NorrisBen Norris
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Across the period, electronegativity increases. This is mainly due to the increase in effective nuclear charge. As the number of core electrons remain constant, the number of protons increases. The protons actually draw those electrons closer to the nucleus.

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answered Feb 9 "16 at 22:42

Matthew LeeMatthew Lee
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Along a period the effective nuclear charge increases thus decreasing the atomic radius. This favours the increase in electronegativity and therefore it increases along a period from left to right.

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answered Jun 3 "16 at 9:47
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Electronegativity means tendency to attract electron,along the period atomic size decreases,atomic size decreases means there is more attraction of nucleus towards electron,more attraction of nucleus means there is more positive charge,and more positive charge means there is more tendency to attract electron.thus electronegativity increases.

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answered Feb 15 "18 at 2:23
Priyanka HazarikaPriyanka Hazarika
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Well the electronegativity increases across the period because the electrons are being added onto the same energy level,this increases the number of electrons of an atom,the increase of electrons of an atom also leads to increase in clear charge,in fact the nuclear charge increases more,this leads to attraction of electrons by the nuclear charge,hence electrons get attracted towards the nuclear charge hence electrons are not easily lost!

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edited May 18 "19 at 8:16
user7951
answered May 18 "19 at 8:14
Hanani MichealHanani Micheal
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