The tendency of an atom in a molecule to attract the shared pair of electron towards itself is called its electronegativity.
Highest value of electronegativity. [for fluorine] is taken as 4.0 and the lowest one[for caesium] as 0.7
Electronegativity. depends on---------
Atomic Size----Greater the size of the atom,the lesser the electronegativity,since the electrons being further away from the nucleus experience a lesser force of attraction.
Nuclear Charge---The greater the nuclear charge,the greater the electronegativity,because increase in nuclear charge causes electrons to be attracted by a greater force,
Trends in Electronegativity
Across a period------ Since the nuclear charge increases due to an increase in atomic number,electronegativity increases from left to right in a period,
For example,in the second period,electronegativity increases from lithium to fluorine,
Down a group----- There is an increase in atomic number down a group, i.e. nuclear charge increases,but due to the addition of extra shells,the atomic size increases.The effect of an increase in the atomic size overcomes the effect of an increase in the nuclear charge,hence electronegativity decreases down a group.
For example,in the first group it progressively decreases from lithium downwards to francium.
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Studied in 10th grade
Saurabh
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Electronegativity is the ability of an atom to attract bonding electrons to itself. Electronegativity increases as you move across and up the Periodic Table to Group 17, making fluorine (F) the most electronegative elemen
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