General Chemistry Lecture 1

Lecture 1 (General Chemistry)

• Lecture presented by Dr. Dina Amin, a lecturer of pharmaceutical organic chemistry
• The lecture is part of a General Chemistry course, likely at BNS University's Faculty of Pharmacy

Lecture Rules

• Attendance is required (time and number)
• Phones must be silenced, except for an emergency call
• Students should be prepared to leave and have questions ready
• Exit the class in case of emergency only twice

Chemistry Fundamentals

• Chemistry studies various substance properties (physical and chemical) and composition
• It examines the structure of substances like ethyl alcohol (CH₃CH₂OH)
• Chemical transformations, such as melting, evaporation, and condensation, are part of chemistry
• Energy changes (absorbed or released) during these reactions are also studied
• Chemistry covers the interactions between atoms and molecules
• Substances can occur naturally or be artificially produced
• These substances contain atoms.

Matter

• Matter is anything that has mass and occupies space
• Pure substances have a definite composition and distinct properties
• Mixtures contain two or more substances, which retain their individual properties
  • Heterogeneous mixtures have a non-uniform composition
  • Homogeneous mixtures have a uniform composition throughout

Classification of Substances

• Examples of substances and their classifications are listed, including:
  • NaCl (compound, homogeneous mixture)
  • Salt Water (homogeneous mixture)
  • Iron (element)
  • Sugar (compound)
  • Air (homogeneous mixture)
  • Helium (element)
  • Water (compound)
  • Salad (heterogeneous mixture)

Element, Compounds & Molecules

• Elements are substances that cannot be broken down into simpler substances by chemical means
• Compounds are made of two or more chemically combined elements in fixed proportions
• Molecules consist of atoms of different elements
• Polyatomic molecules have more than two atoms in a molecule
• Diatomic molecules have two atoms
  • Examples of elements are C, Al, and Ti
  • Examples of polyatomic molecules are S₈ and O₃
  • Examples of diatomic molecules are O₂ and H₂
  • Examples of molecules are H₂O and H₂SO₃

Matter States

• Matter exists in three states: solid, liquid, and gas
• The states differ based on the distance between the molecules

Salts

• Salts are inorganic compounds
• Salts contain acid radicals (anions) and basic radicals (cations)
• Anions are negatively charged ions
• Cations are positively charged ions

Electronegativity

• Electronegativity (EN) is the tendency of an atom to attract electrons
• EN increases across periods (left to right) and decreases down groups (top to bottom)
• Specific EN values are tabulated for different elements
• EN values for Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Beryllium (Be), Carbon (C), Nitrogen (N), Oxygen (O), Fluorine (F), Chlorine (Cl), Bromine (Br), and Iodine (I), are provided .

Chemical Bonds

• Chemical bonds form between atoms to create new compounds.
• Three types of chemical bonds are discussed: Ionic, Covalent Polar, and Covalent Non-Polar
  • Ionic bonds form when the difference in electronegativity (ΔEN) between atoms is greater than 2
  • Covalent Polar bonds form when the difference in electronegativity(ΔEN) is between 0.5 and 2
  • Covalent Non-Polar bonds form when the difference in electronegativity (ΔEN) between atoms is between 0–0.5 . Examples of different atoms and compounds are presented.