Page 15 - Reference Guide For Foreign Pharmacy Licensing Exam Theory

www.pharmacyexam.com Krisman

7. Organic/General Chemistry

Organic chemistry is the chemistry of the compound carbon.

The region in space where an electron is likely to be found is called an orbital. There are different kinds of
orbitals. They have different sizes, shapes and electrons occupancies.

The orbital at the lowest energy level is known as “1s” orbital. It is a sphere with the atomic nucleus, and has the
lowest electron density at the center and therefore; it has the most stability.

The next higher energy level orbital is “2s”. It is larger than the “1s” orbital. Following these there are three
orbitals of equal energy called 2p orbitals. They are dumbbell-shaped. They are known as “2px”, “2py” and
“2pz”.

Electron configuration (Pauli Exclusion Principal):

According to Pauli, only two electrons can occupy an atomic orbital at any given time, and they must bear
opposite spins.

Hybrid orbitals Bond Angle Shape Example

0
SP hybridization 180 Linear BeCl 2
0
2
SP hybridization 120 Trigonal BF 3
3
0
SP hybridization 109.5 Tetrahedral CH 4

Polarity of bonds:

Normally, two nuclei share the electrons in covalent bonds; however many times the electron cloud is denser on
the one atom than the other, depending on the electron withdrawal power of the other atom. This makes one
end of the bond relatively negative and the other end of the bond relatively positive. This type of the bond is
said to be polar and possess polarity.

Hydrogen Fluoride

We can expect covalent bonds to possess polarity when joined atoms have different tendencies to attract
electrons. Below is the list of electronegative elements; fluorine (F) possesses the highest whereas the hydrogen
(H) possesses the lowest electronegativity.

F > O > Cl, N > Br > C, H

43