2: Atomic and Molecular Orbitals

Atomic orbitals are the regions in space where it is more probable to find an electron. This is somehow synonymous to the definition of molecular orbitals though for the latter, the electrons belong to the entire molecule and not to its individual atoms. Another way to put it is that an electron in an atomic orbital is under the influence of only one nucleus of the atom while an electron in a molecular orbital is under the influence of two or more nuclei, depending upon the number of atoms present in the molecule.

The 1s atomic orbital has no node (region where there is zero probability of finding an electron) and has the lowest energy. The 2s atomic orbital is bigger than 1s and is with one node, thus it has higher energy compared to 1s (as more nodes mean higher energy for the orbital). On the three 2p orbitals, the x, y, or z label indicates along which axis the two lobes are directed. It is also understood that in orbital labels, the number tells the principal energy level while the letter tells the shape. The letter s means a spherical orbital; the letter p means a two-lobed orbital.

All the topics above have already been discussed during our Chem14 days thus it wasn't that hard to understand that part of the lecture. The more complicated orbitals though need a bit more refreshing as they are much harder to visualize. If you want to get a better glimpse of them, click here. :)

1: The Basics

The class started with a brief introduction of our professor, Sir West. That was then followed by our introduction of our chosen partners. As today was our first meeting for Ph Ch 125 lec, the main goal was just to acquaint ourselves with the syllabus and the subject itself. Based on the list of topics covered and on the number of those who have to repeat the subject as well, I can already foresee the looming days of stress and hardship. My lack of background on topics 7 onward may also account for such negativity. I am quite positive on one thing though. Sir West said that organic chemistry allows him to think visually and that is possibly a good thing for visual learners like me.

Organic chemistry is a branch of chemistry that focuses on carbon-containing compounds. Life itself will not be possible without the unique ability of carbon to form multiple chains and rings at low energies. This property of carbon may be attributed to its four valence electrons that readily allow bonding to as many as four other atoms. Though silicon is tetravalent as well, it doesn't tend to form double and triple bonds and its high affinity for oxygen is quite disadvantageous (an example is in the formation of silicon dioxide).

It must be taken into consideration though that not all carbon-containing compounds are organic, with carbon dioxide and carbon monoxide as some examples. As I do not know the reason for this, I have tried to look for answers and according to what I have read, a fine line between organic chemistry and inorganic chemistry doesn't exist though some consider the presence of both carbon and hydrogen as the main determining factor as to whether a compound is organic or not.