So do you think noble gases would have a high positive electron affinity, a low positive, or negative electron affinity?
那么,你认为稀有气体的电子亲和能,应该是一个高的正值,一个低的正值,还是一个负值?
- So most of you recognize, if we switch back to the notes, that they do have a negative electron affinity.
看来大部人都想到了,如果你翻翻讲义的话,它们的电子亲和能确实是负的。
The negative ions, these are electron-rich.
二负离子,它们有富裕的电子。
So, what we're looking at here is the force when we have two charged particles, one positive one negative -- here, the nucleus and an electron.
我们现在研究的是,一正一负俩个带电粒子之间的,作用力-在这里。
So this is not going to be a favorable process, we're going to find that the electron affinity is actually a negative 7 kilojoules per mole for nitrogen.
因此这并不是一个容易发生的过程,我们会发现氮的电子亲和能,应该是负的,7,千焦每摩尔。
So for example, that might have a formal charge of negative 1, because to some extent it has gained that much electron density that it now has a formal charge that's negative.
比如,可能它的形式电荷为负一,因为在一定程度上它得到了这么多的共用电子密度,那么它现在就有了负的形式电荷。
And shielding is a little bit of a misnomer because it's not actually that's the electron's blocking the charge from another electron, it's more like you're canceling out a positive attractive force with a negative repulsive force.
屏蔽有一点点用词不当,因为它事实上不是,电子阻挡了来自另一个电子的电荷,它更像你在用一个负排斥力,抵消一个正吸引力,但是屏蔽是考虑这个问题,的很好的方式。
Electron affinity, however, can be either negative or it can be positive.
但是,电子亲和能既可以是负的,也可以是正的。
We have the minus because we're adding a negative charge from the electron.
有这个负号的原因是,我们得到一个电子后增加了一个单位负电荷。
So, an electron has a charge of negative e, we've written here and the nucleus has a charge of positive e.
我们写在这,原子核带正e的电荷,我们看到作用力。
So you don't want to put in a negative energy, that's not going to help you out, you need to put in positive energy to get an electron out of the system. So that's why you'll find binding energies are always negative, and ionization energies are always going to be positive, or you could look at the equation and see it from there as well.
因为这对电离没有帮助,你需要一个正的能量,使得电子脱离这个系统,这就是为什么你会发现,结合能总是负的而电离能总是正的,或者你们看这个方程也可以发现这一点。
So, we were talking, however, about energy in terms of electron affinity, so we can actually relate electron affinity to any reaction by saying if we have this reaction written as here where we're gaining an electron, we say that electron affinity is just equal to the negative of that change in energy.
但是,我们现在讨论的能量,是电子亲和能,因,此我们可以将电子亲和能,与任何反应联系起来,只要我们将反应写成这种得到电子的形式,我们说电子亲和能就等于,反应前后能量变化的负值。
We're going to get to more complicated atoms eventually where we're going to have more than one electron in it, but when we're talking about a single electron atom, we know that the binding energy is equal to the negative of the Rydberg constant over n squared, so it's only depends on n.
我们以后会讲到,更加复杂的情况,那时候,不只有一个原子,但当我们讲,单个原子的时候,我们知道结合能,等于,负的Rydberg常数,除以n平方,所以它仅仅由n决定的。
And what we say when we talk about the delta energy is I E 2 that this is going to be equal to i e 2, or the second ionization energy, or we could say the negative of the binding energy of a 2 s electron in b plus.
那么我们说,Δ,E,应该等于,或者说第二电离能,也就是正一价硼中,2,s,电子的,束缚能的负值。
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