Chemistry Lecture Notes

Introduction

• Focus: Chemistry
• Useful for beginners or those taking a chemistry course

Periodic Table Overview

• Group 1 (Alkali Metals)
  • H (Hydrogen)
  • Li (Lithium)
  • Na (Sodium)
  • K (Potassium)
  • Rb (Rubidium)
  • Cs (Cesium)
  • Properties: Form ions with a +1 charge, 1 valence electron
• Group 2 (Alkaline Earth Metals)
  • Be (Beryllium)
  • Mg (Magnesium)
  • Ca (Calcium)
  • Sr (Strontium)
  • Ba (Barium)
  • Properties: Form ions with a +2 charge, 2 valence electrons
• Group 13 (Group 3A)
  • B (Boron)
  • Al (Aluminum)
  • Ga (Gallium)
  • In (Indium)
  • Tl (Thallium)
  • Properties: Form ions with a +3 charge
• Group 14 (Group 4A)
  • C (Carbon)
  • Si (Silicon)
  • Ge (Germanium)
  • Sn (Tin)
  • Pb (Lead)
  • Properties: Form ions with +2 or +4 charges
• Group 15 (Group 5A)
  • N (Nitrogen)
  • P (Phosphorus)
  • As (Arsenic)
  • Sb (Antimony)
  • Bi (Bismuth)
  • Properties: Form ions with a -3 charge, 5 valence electrons
• Group 16 (Group 6A)
  • O (Oxygen)
  • S (Sulfur)
  • Se (Selenium)
  • Te (Tellurium)
  • Po (Polonium)
  • Properties: Form ions with a -2 charge, 6 valence electrons
• Group 17 (Group 7A)
  • F (Fluorine)
  • Cl (Chlorine)
  • Br (Bromine)
  • I (Iodine)
  • Properties: Form ions with a -1 charge, 7 valence electrons
• Group 18 (Group 8A)
  • He (Helium)
  • Ne (Neon)
  • Ar (Argon)
  • Kr (Krypton)
  • Xe (Xenon)
  • Properties: Noble gases, chemically inert
• Transition Metals (Groups 3-12) and Inner Transition Metals (Lanthanides and Actinides)
  • Common elements: Ti (Titanium), Cr (Chromium), Mn (Manganese), Fe (Iron), Co (Cobalt), Ni (Nickel), Cu (Copper), Zn (Zinc), Ag (Silver), Cd (Cadmium), Hg (Mercury), Au (Gold), Pt (Platinum), Pd (Palladium)
  • Inner transition metals: Th (Thorium), U (Uranium)

Atoms vs Molecules

• Atoms: Single particles (e.g., Zn, Fe, Al)
• Molecules: Particles consisting of two or more atoms (e.g., H2, N2, O2, Cl2)
• Elements vs Compounds
  • Pure elements: Made of one type of atom (e.g., Zn, H2)
  • Compounds: Made of different types of atoms (e.g., NaCl, H2O)
• Types of Compounds
  • Ionic Compounds: Metals + nonmetals, consists of ions (e.g., NaCl, MgO)
  • Molecular Compounds: Nonmetals bonded together (e.g., CO2)
• Metalloids: Elements with properties of both metals and nonmetals (e.g., B, Si, Ge)

Naming Compounds

• Molecular Compounds
  • Use prefixes to indicate the number of atoms (e.g., CO2: Carbon dioxide)
  • Common prefixes: Mono-, Di-, Tri-, Tetra-, Penta-, Hexa-, Hepta-, Octa-, Nona-, Deca-
• Ionic Compounds
  • Name = Metal + Nonmetal (with -ide suffix) (e.g., KBr: Potassium bromide)
  • Do not use prefixes
  • For transition metals, indicate charge with Roman numerals (e.g., FeCl2: Iron(II) chloride)
• Polyatomic Ions
  • Common ions: SO4^2- (Sulfate), OH^- (Hydroxide), NH4^+ (Ammonium), NO3^- (Nitrate), PO4^3- (Phosphate), CN^- (Cyanide)

Writing Formulas for Compounds

• Molecular Compounds
  • Reverse naming rules (e.g., Phosphorus pentachloride: PCl5)
• Ionic Compounds
  • Balance charges (e.g., Aluminum sulfate: Al2(SO4)3)
  • Use parentheses for multiple polyatomic ions

Isotopes

• Definition: Atoms of the same element with different numbers of neutrons
• Examples
  • Carbon-12 and Carbon-13
  • Isotopes have the same number of protons but different numbers of neutrons
• Atomic Number: Number of protons, identifies the element
• Mass Number: Sum of protons and neutrons, identifies the isotope
• Calculating Particles
  • Protons = Atomic number
  • Neutrons = Mass number - Atomic number
  • Electrons = Protons - charge (for ions)

Practice Problems

• Identifying whether substances are atoms, molecules, elements, or compounds
• Naming various molecular and ionic compounds
• Writing chemical formulas based on compound names
• Calculating the number of protons, neutrons, and electrons in different isotopes and ions
• Examples covered: Sulfur trioxide (SO3), Chlorine gas (Cl2), Magnesium (Mg), Sulfur (S8), Lithium bromide (LiBr), and more