Periodic Trends

[EriMizuguchi2K]

Hi,

Besides atomic radius, electron affinity, and ionization energy, what other periodic trends should we know?

[205705413]

You also need to know the trends for the ionic radius. You can always check the outlines on the chem 14 website to see what you need to know.
https://lavelle.chem.ucla.edu/wp-conten ... _World.pdf

[Andrea_Perez_2F]

During the Monday lecture, Professor Lavelle also went over ionic radii, it is pretty similar to atomic radii so make sure to know about that one too

[Sasha Gladkikh 2A]

Hi,

Dr. Lavelle also discussed the ionic radius trend during last Monday's (10/18) lecture.

The ionic radius is the distance between the nucleus and the electron in the outermost shell of an ion.
• When an atom loses an electron to form a cation, the lost electron no longer contributes to shielding the other electrons from the charge of the nucleus; consequently, the other electrons are more strongly attracted to the nucleus, and the radius of the atom gets smaller.
• When an electron is added to an atom, forming an anion, the added electron repels other electrons, resulting in an increase in the size of the atom.

Here is a diagram that illustrates this trend:

(Note: The neutral atoms are colored gray, cations red, and anions blue.)

• As with other types of atomic radii, ionic radii increase upon descending a group and decrease going across a period. Note that this only applies if the elements are the same type of ion, either cations or anions. For example, while neutral lithium is larger than neutral fluorine, the lithium cation is much smaller than the fluorine anion, due to the lithium cation having a different highest energy shell.

Hope this helps!

[Ashley Presnell 1C]

Ionic radius follows a similar trend to atomic radius but has differences when looking at the trend of a cation versus an anion.