Periodicity

Today during class we discussed the trends that have recently appeared in the organization of the Periodic Table. Using the graphs we created the previous day, we looked at Ionization Energy and Atomic Radius in relation to the elements, and their organization in periods and groups.
1. First Ionization Energy (the difficulty of losing one electron--first level)
--As you move top to bottom in groups, it is easier to lose electrons, therefore the first ionization energy decreases. This is because as you move further down, there are more levels of electron orbitals, and they are easier to loose the farther they are from the nucleus
--As you move left to right in periods, it becomes harder to lose electrons, therfore the first ionization energy increases. This is because as you move across left to right the atomic number increases therefore so do the number of protons, which means there is greater pull on the electrons you are trying to lose.

2. Atomic Radius (size)
--As you move top to bottom in groups, the atomic radii increase. This is because there are more levels surrounding the nucleus, therefore larger atoms
--As you move left to right across the periods, the atomic radii decreases. This is because as you move across periods, the atomic numbers increase, and therefore so do the number of protons in the atom. The greater number of protons, the larger pull on the electron orbitals. The greater the pull on the orbitals, the closer they will be pulled into the nucleus, in turn the atoms will be smaller.

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Rachel Mann