Yes. It's true. Chlorine has the highest electron affinity, then Fluorine, Bromine and Iodine
Generally electron affinity goes up as you go from left to right across the Periodic Table, and decreases as you go down a column. However, fluorine is an exception -- and the element with the highest electron affinity is chlorine (note that the most electronegative element is fluorine however).The reason that the electron affinity is not as high as might otherwise be predicted for fluorine is that it is an extremely small atom, and so it's electron density is very high. Adding an additional electron is therefore not quite as favorable as for an element like chlorine where the electron density is slightly lower (due to electron-electron repulsion between the added electron and the other electrons in the electron cloud).Note that there are a number of other exceptions to the general rule of electron affinity increasing towards the upper right corner -- see the Related Questions links to the left for an explanation of some of those other exceptions.See also the Web Links to the left for more information about electron affinities and the fluorine-chlorine exception.
AnswerElectron affinity is the energy released when we add an electron to the outermost orbit of the atom. Halogens are the higher in electron affinity, and chlorine has the higher electron affinity than rest of the halogens. The irregularity in the electron affinity trend between Cl and F is due to the small size of the F atom. Although F definitely has a higher attraction for an electron than Cl (as evidenced by its high electro negativity value), the small size of the F atom means that adding an electron creates significant repulsion. Since electron affinity is an energy measurement, the total energy associated with electron affinity winds up being the energy that is released by the electron binding to the nucleus, minus the energy involved in overcoming the electrical repulsion in the outer shell.This makes the fluoride anion so formed unstable due to a very high charge/mass ratio. Also, fluorine has no d electrons which limits its atomic size. As a result, fluorine has an electron affinity less than that of chlorine.
The outer electrons in bigger halogens are further from the nucleus and so they feel less attraction and so are easier to remove. Therefore, astatine has the lowest ionisation potential of the halogens.
Generally, electron affinity increases (becomes less negative) in groups/families moving from top to bottom.
Generally electron affinity goes up as you go from left to right across the periodic table, and decreases as you go down a column. However, fluorine is an exception -- and the element with the highest electron affinity is chlorine (note that the most electronegative element is fluorine however).The reason that the electron affinity is not as high as might otherwise be predicted for fluorine is that it is an extremely small atom, and so it's electron density is very high. Adding an additional electron is therefore not quite as favorable as for an element like chlorine where the electron density is slightly lower (due to electron-electron repulsion between the added electron and the other electrons in the electron cloud).Note that there are a number of other exceptions to the general rule of electron affinity increasing towards the upper right corner -- see the Related Questions links to the left for an explanation of some of those other exceptions.See also the Web Links to the left for more information about electron affinities and the fluorine-chlorine exception.
Generally electron affinity goes up as you go from left to right across the Periodic Table, and decreases as you go down a column. However, fluorine is an exception -- and the element with the highest electron affinity is chlorine (note that the most electronegative element is fluorine however).The reason that the electron affinity is not as high as might otherwise be predicted for fluorine is that it is an extremely small atom, and so it's electron density is very high. Adding an additional electron is therefore not quite as favorable as for an element like chlorine where the electron density is slightly lower (due to electron-electron repulsion between the added electron and the other electrons in the electron cloud).Note that there are a number of other exceptions to the general rule of electron affinity increasing towards the upper right corner -- see the Related Questions links to the left for an explanation of some of those other exceptions.See also the Web Links to the left for more information about electron affinities and the fluorine-chlorine exception.
AnswerElectron affinity is the energy released when we add an electron to the outermost orbit of the atom. Halogens are the higher in electron affinity, and chlorine has the higher electron affinity than rest of the halogens. The irregularity in the electron affinity trend between Cl and F is due to the small size of the F atom. Although F definitely has a higher attraction for an electron than Cl (as evidenced by its high electro negativity value), the small size of the F atom means that adding an electron creates significant repulsion. Since electron affinity is an energy measurement, the total energy associated with electron affinity winds up being the energy that is released by the electron binding to the nucleus, minus the energy involved in overcoming the electrical repulsion in the outer shell.This makes the fluoride anion so formed unstable due to a very high charge/mass ratio. Also, fluorine has no d electrons which limits its atomic size. As a result, fluorine has an electron affinity less than that of chlorine.
The outer electrons in bigger halogens are further from the nucleus and so they feel less attraction and so are easier to remove. Therefore, astatine has the lowest ionisation potential of the halogens.
Generally, electron affinity increases (becomes less negative) in groups/families moving from top to bottom.
The reason that the electron affinity is not as high as might otherwise be predicted for fluorine is that it is an extremely small atom, and so it's electron density is very high. Adding an additional electron is therefore not quite as favorable as for an element like chlorine where the electron density is slightly lower (due to electron-electron repulsion between the added electron and the other electrons in the electron cloud).
Generally electron affinity goes up as you go from left to right across the periodic table, and decreases as you go down a column. However, fluorine is an exception -- and the element with the highest electron affinity is chlorine.(Note that the most electronegative element is fluorine however; 'electronegativity' is not exactly the same as 'electron affinity'.)Electronegativity is the ability of an atom in a molecule to draw bonding electrons to itselfElectron affinity is a measure of the energy change when an electron is added to a neutral atom to form a negative ion.The reason that the electron affinity is not as high as might otherwise be predicted for fluorine, is that it is an extremely small atom, and so it's electron density is very high. Adding an additional electron is therefore not quite as favorable as for an element like chlorine where the electron density is slightly lower (due to electron-electron repulsion between the added electron and the other electrons in the electron cloud).
Di-Negative atoms are already electron rich in nature. This causes electron affinity is less. Since energy is needed to introduce another electron into the atom the process is endothermic.
Generally electron affinity goes up as you go from left to right across the periodic table, and decreases as you go down a column. However, fluorine is an exception -- and the element with the highest electron affinity is chlorine (note that the most electronegative element is fluorine however).The reason that the electron affinity is not as high as might otherwise be predicted for fluorine is that it is an extremely small atom, and so it's electron density is very high. Adding an additional electron is therefore not quite as favorable as for an element like chlorine where the electron density is slightly lower (due to electron-electron repulsion between the added electron and the other electrons in the electron cloud).Note that there are a number of other exceptions to the general rule of electron affinity increasing towards the upper right corner -- see the Related Questions links to the left for an explanation of some of those other exceptions.See also the Web Links to the left for more information about electron affinities and the fluorine-chlorine exception.
The energy change that occurs when an electron is added to a neutral atom. This is usually exothermic. Noble Gases are excluded from this. Equation: X(element)+e-(electron)---------> X-1+ energy
There can not be any reason, because the premise is not true: Group 7 elements become less rather than more reactive from fluorine to iodine.
sodium has one electron more(2,8,1) and fluorine has 1 electron less(2,7) But neon has a stable configuration(2,8,8).
Iodine is very less abundant compared to fluorine and chlorine and it is found in seawater also with chlorides,bromides etc and certain forms of marine life also contain Iodine in their systems.Eg Seaweeds