Team 44S!

Last night was rough- I was pulled out of bed by a friend who had an “emergency” and needed to be picked up from the airport at the crack of dawn. She also demanded girl time and being a good friend, I agreed without hesitation. I spent the entire day and most of the night with her. I came home exhausted and in dire need of sleep, however, as I walked in I was greeted by Liz, Vince and a picture Liz drew and posted on the fridge. The picture included my face along with hers and Vince’s with a heading that read TEAM 44S! That was enough motivation to get me to hit the books for a few hours before going to bed at 3 am. Well done Liz. This morning I had class at Berkeley Review we covered Periodic Trends in General Chemistry. Pretty cut and dry basic stuff. I learned that the periodic trends are based on:

1). Effective Nuclear Charge: which affects how tightly valence shell electrons are held. Cations are generally smaller than the neutral atom while anions are larger. As the number of protons increase, the atom cotracts due to an increase in electrostatic attraction. As the number of electrons increase, the atom expands due to an increase in repulsive forces. This trend is observed in atoms that are in the same row and increases going from left to right on the periodic table. Effective nuclear charge affects ionization energy (the amount of energy required to lose an electron), electron affinity (the amount of energy released with the gain of an electron), and atomic radius.

2). Valence Shell (principle quantum number- n): which affects the distance between electrons and the nucleus. As distance increases, attraction decreases. Valence shell trend is observed when atoms are in the same period or column of the periodic table. As the table decends (top to bottom) valence shells increase. Electronegativity can be predicted using this trend.

As with everything in life, there are exceptions in these trends. Exceptions are usually observed with half-filled and filled stability. Time for BED!