Ionization Energy

[Tracy Tran 3L]

What is ionization energy and electron affinity? I am having a hard time understanding these concepts from the online lecture.

[Janice Hu 2L]

Ionization energy = amount of energy needed to remove an electron from an atom (atom becomes cation)
Electron affinity = amount of energy released (or the energy change) when an electron is gained by an atom (atom becomes anion)

If it helps to remember, affinity refers to a strong attraction, so you can think of an atom and electron being strongly attracted to each other for electron affinity (thus the atom gains an electron and electron affinity refers to the energy released from that) :)

[Sristi Palimar 2E]

I agree with the more formal definitions of ionization energy and electron affinity mentioned above. More conceptually, you can think of ionization energy as an atoms willingness to give up electrons, and electron affinity as an atoms willingness to keep electrons.

Ionization energy and electron affinity both increase up and to the right across the periodic table. Atoms with greater ionization energy are less willing to give up electrons, as it requires a significant amount of energy to do so. This can also be attributed to the fact that atoms with high ionization energy must also have a high electron affinity, as they seek to hold onto their electrons

[Alexander Moroz 1B]

Adding on to the previous answers, ionization energy differs based on the stability of atoms. Very stable atoms like Ne with a full electron shell would not want to get rid of an electron, so they would have very high ionization energy. it would take a lot to remove one of its electrons because this would cause it to move from a stable to unstable form. Atoms like K would benefit from losing an electron because it would bring them closer to have a full outer electron shell and being in a more stable state. It would have a lower ionization energy.

[Sharlene Duong 3E]

Ionization energy refers to the energy needed to remove electrons from an atom, while electron affinity is how easily an atom accepts electrons (or the energy released when electrons are added to an atom).

In order to better understand ionization energy, you should think about the trend of atomic radius. Atomic radius decreases from left to right across a period because the increasing molecular charge holds the electrons tighter. Atomic radius increases going down a group because there are more shells. Now if you think back to ionization energy, the farther away an electron is from the nucleus, the easier it is to remove. So, the larger the radius, the easier it is to remove the electron and the less energy you will need. Therefore ionization energy will increase from left to right as the radius decreases and ionization energy will decrease going down a group as radius increases.

In regards to electron affinity, when looking at the periodic table, the elements in the top right of the periodic table have higher electron affinity. These elements are more prone to accepting electrons since they have a negative charge than the elements on the left side of the periodic table that have a positive charge.

[WendyN_L2]

To add on about electron affinity, it tells you the energy change that occurs when you add an electron to the atom. If the electron wants to jump to a more stable state they will release energy from gaining an electron. While if an electron already has full orbitals they will absorb energy, because it takes energy to add an electron. The elements that wants to gain an electron want to fill their shells, such as those in Group 7. For example Cl the configuration Is [Ne]3s^2 3p^5.. it wants one more electron to fill the shell. There's a question regarding this topic on week 2 #30 hw, so maybe this will help.

[Shawn Suen]

Ionization energy is the amount of energy required to remove an electron from an atom in the gaseous state while electron affinity is the amount of energy released when an atom takes in an electron.

[Jacob Bright 1C]

Ionization energy is the energy that is required to remove an electron from an an atom in its gaseous state. The trend for ionization energy is as follows: ionization energy decreases down a group and increases across a period. This is due to the fact that electrons that lie further away from the nucleus are the easiest to remove and as such require the least ionization energy.
Electron affinity on the other hand is the amount of energy that is released when an additional electron is added to an atom in its gaseous state. The trend for electron affinity on the periodic table is less periodic than some other trends such as ionization energy and atomic radius, but there is still a general trend towards elements in the upper right-hand side of the periodic table having the highest electron affinities.
Both quantities can be easily confused since they both refer to a certain amount of energy associated with transferring electrons, but I find it easy to distinguish the two when I remember their differing trends. Hope this helps!

[Anish_Marripati_2F]

Ionization energy is the amount of energy required to remove an electron. Generally, Ionization energy increases across a period and decreases down the group. Electron affinity, on the other hand, is the amount of energy released when you gain an electron. Electron Affinity decreases as you go down a group, but increases across the period.

[Yalit Gonzalez 1A]

Ionization energies decrease down a group and increase across a period.