1. Chapter 1 Introduction Adel M. Awadallah Islamic University of Gaza
Organic chemistry for medicine and biology students
Chem 2311
Chapter 1
Introduction
By Prof. Dr.
Adel M. Awadallah
Islamic University of Gaza

2. Ionic Compounds
They are formed by the transfer of one or more valence electrons from one atom to another
Electropositive atoms: give up electrons and form cations.
Electronegative atoms: accept electrons and form anions
Ionic compounds: are composed of positively charged cations and negatively charged cations

3. Covalent compounds
A covalent bond: is formed when two atoms share one or more electron pairs. A molecule consists of two or more atoms joined by covalent bonds
Bond energy: is the energy necessary to break a mole (6.022 x 1023)of covalent bonds.
Bond length: is the average distance between two covalently bonded atoms

4. Valence and bonding in organic compounds

5. Polarity of Bonds: depends on the electronegativity difference

6. Examples:

7. Isomers: different compounds having the same molecular formula

8. Abbreviated structural formulas

9. Formal charge = Valence electrons – bonds – electrons
Formal Charges: are the charges that each atom carries, and can be calculated as follows
Formal charge = Valence electrons – bonds – electrons
Example:
Resonance: arises whenever we can write two or more structures for a molecule with different arrangements of electrons but identical arrangement of atoms

10. Arrows:

11. Classification of organic compounds according to functional groups