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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: wakka on May 02, 2006, 09:26:58 PM

Title: Electron affinity..
Post by: wakka on May 02, 2006, 09:26:58 PM
How can an atom RELEASE energy if it's ATTRACTING an electron... wouldn't it release energy if it was releasing an electron, ionization-style? also how do EA and IE relate when talking about electrons moving from one atom to another.
Title: Re: Electron affinity..
Post by: Yggdrasil on May 02, 2006, 10:42:58 PM
Consider a falling object.  A falling object is attracted by the Earth, and as it falls, the object loses potential energy and releases it as kinetic energy.  On the other hand, an object traveling upwards must be given an initial kinetic energy to escape the Earth's gravitational pull.

In the same manner, an electron being attracted by a nucleus loses potential energy and releases energy in the form of heat (kinetic energy) or light.  Similarly, an electron moving away from a nucleus, must absorb energy in order to escape the attraction of the nucleus.

[this is of course, a very simplified analogy because the sittuation isn't as simple as the electron being attracted by the nucleus, but it illustrates the concept well enough]
Title: Re: Electron affinity..
Post by: wakka on May 03, 2006, 10:51:36 PM
Consider a falling object.  A falling object is attracted by the Earth, and as it falls, the object loses potential energy and releases it as kinetic energy.  On the other hand, an object traveling upwards must be given an initial kinetic energy to escape the Earth's gravitational pull.

In the same manner, an electron being attracted by a nucleus loses potential energy and releases energy in the form of heat (kinetic energy) or light.  Similarly, an electron moving away from a nucleus, must absorb energy in order to escape the attraction of the nucleus.

[this is of course, a very simplified analogy because the sittuation isn't as simple as the electron being attracted by the nucleus, but it illustrates the concept well enough]

losing potential energy = gaining kinetic energy it sounds like... like if it were graphed it would be a parabola and the P.E would decrease as it got close to it's peak right?

something i don't understand about your analogy is that, if a space ship is leaving from earth isn't that kind of like.. giving off energy in a way, like it's PUSHING it away. and if an object fell and hit the earth's surface wouldn't the impact go INTO the ground... doesn't sound like the ground is releasing energy.. maybe i missed something