7.2 ionization of energy Flashcards
Ionization Energy = the energy it takes to remove an electron from an gasious atom to form a gasious ion
* doesnt have to be a noble gas just a gas
electrons are products in ionization rxns. Meaning it will take energy to remove that electron away from the nucleus. It attracted to the proton core and doesnt want to be removed, so needs something w/ E to remove it.
These are endothermic rxns
* The system is gaining energy and the environment is losing it (endo = within the system).
The E needed to remove electrons from the nucleus is that you need more energy to remove electrons from smaller atoms
* This makes sense, think about Fr, the biggest atom. Its valence electrons are so shielded from the protons that they’re barley attracted, and it has few protons when compared to valence electrons (has a very low effective nuclear charge, just a +1 for this group 1)
* So this is the easist one to pluck off
Fr is the largest in terms of anatomic radii, however, its the smallest in terms of ionization E
You can see below that as you move from left to right and from down to up you’ll have an increasing ionization energy (because those valence electrons are more attracted to the nucleus)
* however, the ones dipicted in red below are some of the exceptions
For Be, it has a filled S subshell, its configuration ends w/ S^2. That means its stable. So losing an electron when you’re in a stable place means its going to cost a little bit more E (it likes being in that place)
Nitrogen has a half filled P subshell
* P^3
* When you have a half filled subshell, meaning all their spins align, meaning its in a more stable place, meaning it costs slightly more E to detach one of those valence electrons
These two trends continue down the periodic table a couple rows (so the thingsunder Be and N)
* Be is higher than B
* Mg is higher than Al
* Ca is higher than Ga
* N higher than O
* P higher than S
* As higher than Se
Its also true fo a filled D shell (takes more E to ionize the one the left unlike our trend)
* Zn higher than Ga
* Cd higher than In
* Hg higher than Ti
opposite of anatomic radius
the ones in reds are the exceptions, where it takes more E to ionize them than the group to the R (which is opposite our current trend)
Which one has the biggest ionization E, Li, Be, B or C?
C. Its furthest to the R
* meaning its also the smallest anatomic radius listed, which means the nucleus is holding its protons tighter, which is why it takes more E to ionize it (tear off 1 of the valence electrons)
Which has the highest ionization E, Be, B, C, N, O.
So remember, N actually takes more E to ionizae than O because its got that half filled P subshell (which a more stable state, meaning it takes more E to ionize it than the atom to its R)
Nitrogen
Sucessive Ionization Energies
* So this is when you remove more than 1 valence electron
* Before we were just talking about removing the first valence electron, now were removing more
The trend we just learned applies only to the first ionizatin energy (what it takes to remove 1 valence electron)
KNOW: it is much easier to remove a valence electron than a core electron
* B: 1s^2, 2s^2, 2p1
* Boron has 3 valence electrons in its second shell (remember, we just look at the ones w/ that n = 2 number because thats the most outer shell)
* 2 core electrons in the 1s
**The reason the second ionization costs more E than the first is that when an element loses an electron it becomes significantly smaller (the electrons around the nucleus are less repulsed by eachother) so the group in near the core. They’re now more attracted to the nucleus, meaning it takes more E to detach them. **
* When you move passed the valence electrons and into the next orbit (that is even closer to the nucleus) thats where it starts taking loads more E
this is representing the ionization E for when valence electrons become core electrons
If they asked what element it was, youd know it had 3 valence electrons, so its in group 13
Which of the following has the most second ionization E, Na, Mg, Al, Si.
Valence electrons:
* Na = 1
* Mg = 2
* Al = 3
* Si = 4
Dont use that general trend, thats for the first ionization E.
* this is obvisouly Na, because you’re then removing a core electron, not a valence electron, which takes loads more E
* all the rest are just removing valence electrons which are much lower in E
This is talking about first ionization E so we can use our trend of smaller atomic radii = higher ionization E
P
nitrogen due to the exception
n = 1s^2, 2s^2, 3p^3
* its p orbital is half full, meaning it actually takes more E to ionize it becuase its at a lower E state (meaning it takes more E to detach it)
its because its an exception
c
Li only has 1 valence elctron, meaning the second one will be a core electron and take much more E to ionize
* 1s^2, 2s^1
* So essentially we just removed that 1 electron in the 2s^1 orbital and the second would be in that lower orbit (1), meaning it would take exponentially more E
all the others have multiple valence electrons
