quick question about electron affinity

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evo

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so far i have 2 contradicting ideas: ek audio osmosis says it gets more positive when you go left to right and up the periodic table, which means fluorine has the most positive ea, but gold standard practice exam 1 says it gets more positive as it goes right to left and down the periodic table.

im not sure which one i should believe, this positive and negative thing confuses me.

any help will be appreciated

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For electronegativity, it increases as you go from left to right and decreases as you go from top to bottom. "Electropositivity" is just the reverse order.

So, Fluorine is the most electronegative element in the periodic table.
 
For electronegativity, it increases as you go from left to right and decreases as you go from top to bottom. "Electropositivity" is just the reverse order.

So, Fluorine is the most electronegative element in the periodic table.

i thought electron affinity is the energy change when an atom receives an electron, which is a bit different from electropositivity
 
so far i have 2 contradicting ideas: ek audio osmosis says it gets more positive when you go left to right and up the periodic table, which means fluorine has the most positive ea, but gold standard practice exam 1 says it gets more positive as it goes right to left and down the periodic table.

im not sure which one i should believe, this positive and negative thing confuses me.

any help will be appreciated

I've always been taught that when energy is released from a system, the sign is negative, and when a system gains energy, the sign is positive.

Since we're dealing with electron affinity here, the larger the negative value, the more favorable the reaction. Therefore, the more electronegative an atom, the more potential energy it releases when it gains another electron. In regards to Fluorine, the EA should be a relatively large negative value.

TBR says that "an element releases more energy upon gaining an electron as you move left to right in the periodic table." And that "an element also releases more energy upon gaining an electron as you ascend a column in the periodic table."

Personally, I think you should listen to Gold Standard on this one.
 
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I've always been taught that when energy is released from a system, the sign is negative, and when a system gains energy, the sign is positive.

Since we're dealing with electron affinity here, the larger the negative value, the more favorable the reaction. Therefore, the more electronegative an atom, the more potential energy it releases when it gains another electron. In regards to Fluorine, the EA should be a relatively large negative value.

TBR says that "an element releases more energy upon gaining an electron as you move left to right in the periodic table." And that "an element also releases more energy upon gaining an electron as you ascend a column in the periodic table."

Personally, I think you should listen to Gold Standard on this one.

thanks for the clarification :), the ek chem book actually agrees with gold standard's definition but audio osmosis says the exact opposite for some reason :confused:
 
Sorry, I didn't answer your question :D I was feeding on the strength of electron affinity. More electronegativity means more attractive pull of the nucleus for electrons. As to why they are different probably because of the sign conventions they use for their materials. Positive electron affinity happens when an electron is added vs. Negative electron affinity indicates the release of energy. (Both saying the same thing) (Akarat already mentions this). However, understanding the how and why probably is not a bad idea when someone uses positive or negative for his/her convention.
 
Electron affinity is defined as how much energy is released when an electron is added. More energy is released going up and to the right.

X + e- ---> X-
delta E of this reaction < 0

That means delta E of the reaction is more negative as more energy is released. So delta E is more positive going to the left and down.

For the MCAT, assume electron affinity is defined as how much energy is released (eg how negative is delta E of the reaction or the absolute value of delta E) unless told otherwise.
 
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