Lecture 1 General Chemistry PDF

By:- Dr Dina Amin LECTURE 1 (Lecturer of Pharmaceutic al Organic (GENERAL CHEMISTRY) Chemistry) 1  CHEMISTRY Lecture rules. ...

By:- Dr Dina Amin LECTURE 1 (Lecturer of Pharmaceutic al Organic (GENERAL CHEMISTRY) Chemistry) 1  CHEMISTRY Lecture rules.  Attendance (time, number)  Phone (silent, one emergency call)  System (be quit, have questions)  Exit (emergency case, two times ) 2  CHEMISTRY  Chemistry is the science that deals with the properties ( physical and chemical properties), composition e.g C2H5OH or C2H8 , and structure of substance e.g Ethyl alcohol (CH3CH2OH) , the transformations they undergo (melting, evaporation , and condensation), and the energy that is released or absorbed during these processes..  Every substance, whether naturally occurring or artificially produced consist of one or more of the hundred-odd species of atoms.  Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. 3 MATTER 4 MATTER 5 : MATTER 6  MATTER STATE : 7  SALTS : 8  SALTS : 9 : ELECTRONEGATIVITY * Electronegativity (EN): it is the tendency or the ability of an atom to attract electrons. EN increases in the same period with the increase in the atomic number while decrease in the same group increase in the atomic number. e.g.: H (2.2) Li (1.0) Be (1.6) B (2.0) C (2.6) N (3.0) O (3.4) F (4.0) Na (0.9) Cl (3.2) K (0.8) Br (3.0) I (2.7) 10 : CHEMICAL BONDS * Types of Chemical Bonds: According to the difference in EN between the bonded atoms, the chemical bonds are classified into: 1- Ionic Bonds: It occurs when the difference ΔEN > 2. Here, the atoms carry complete charges and are dissociated into separate ions in solution (cations and anions). e.g. Sodium Chloride: Na+Cl- (ΔEN = 2.3). 11 : CHEMICAL BONDS 2 - Covalent Polar Bonds: It occurs when the difference 2 > ΔEN > 0.5. Here, the more electronegative atom carries partial negative charge (-δ) and the less electronegative atom carries partial positive charge (+δ). They are not dissociated to separate ions in solution. e.g. Methyl Chloride: H3C+δ-Cl-δ (ΔEN = 0.6). Methyl Lithium: H3C-δ-Li+δ (ΔEN = 1.6). 12 : CHEMICAL BONDS 3 - Covalent Non-Polar Bonds: bond that is formed when electrons are shared equally between two atoms (atoms with same EN). It occurs when the difference ΔEN = 0 to 0.5. Here, bonded atoms don't carry charges. e.g. Bromine: Br-Br, Ethane: H3C-CH3 (ΔEN = 0). 13 : CHEMICAL BONDS 14 : CHEMICAL REACTIONS Thank You With my best wishes Dr. Dina Amin 15