Introduction to Chemistry: Basics and the Periodic Table

Jun 17, 2024

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Chemistry Basics

The Periodic Table

  • Group 1 (Alkaline Metals): H (Hydrogen), Li (Lithium), Na (Sodium), K (Potassium), Rb (Rubidium), Cs (Cesium)
    • Typically form ions with +1 charge
  • Group 2 (Alkaline Earth Metals): Be (Beryllium), Mg (Magnesium), Ca (Calcium), Sr (Strontium), Ba (Barium)
    • Form ions with +2 charge
  • Group 13 (Group 3A): B (Boron), Al (Aluminum), Ga (Gallium), In (Indium), Tl (Thalium)
    • Form +3 charges
  • Group 14 (Group 4A): C (Carbon), Si (Silicon), Ge (Germium), Sn (Tin), Pb (Lead)
    • Form +2 or +4 charges
  • Group 15 (Group 5A): N (Nitrogen), P (Phosphorus), As (Arsenic), Sb (Antimony), Bi (Bismuth)
    • Typically form -3 charges
  • Group 16 (Group 6A): O (Oxygen), S (Sulfur), Se (Selenium), Te (Tellurium)
    • Form -2 charges
    • Known as Chalcogens
  • Group 17 (Group 7A): F (Fluorine), Cl (Chlorine), Br (Bromine), I (Iodine)
    • Form -1 charges
    • Known as Halogens
  • Group 18 (Group 8A): He (Helium), Ne (Neon), Ar (Argon), Kr (Krypton), Xe (Xenon)
    • Known as Noble Gases
    • Chemically inert, very stable
  • Groups 3-12: Transition Metals
    • Examples: 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: Lanthanide and Actinide series
    • Common examples: Th (Thorium) and U (Uranium)

Atoms vs. Molecules

  • Atoms: Single units of elements; e.g. Zn (Zinc), Fe (Iron)
  • Molecules: Particles composed of two or more atoms; e.g. H2 (Hydrogen), O2 (Oxygen)
  • Elements: Pure substances made of one type of atom; e.g. Zn, H2
  • Compounds: Substances composed of different types of atoms; e.g. NaCl (Sodium chloride), H2O (Water)
    • Ionic Compounds: Metal + Non-Metal; form ions; e.g. NaCl, MgO (Magnesium oxide)
    • Molecular Compounds: Non-metals bonded to each other; e.g. CO2 (Carbon dioxide)

Metals, Non-Metals, and Metalloids

  • Metals: Conduct electricity, left side of periodic table
  • Non-Metals: Insulators, right side of periodic table
  • Metalloids: Properties in-between metals and non-metals
    • Examples: B (Boron), Si (Silicon), Ge (Germanium), As (Arsenic), Sb (Antimony), Te (Tellurium)
    • Know Germanium and Silicon

Distinguishing Types of Substances

  • Atoms: Pure elements composed of individual atoms; e.g. Fe
  • Molecules: Pure elements or compounds composed of molecules; e.g. H2, CO2
  • Ionic Compounds: Metals + Non-Metals; e.g. NaCl, KBr (Potassium bromide)
  • Molecular Compounds: Composed of non-metals only; e.g. CO2, NH3 (Ammonia)

Polyatomic Ions

  • Group of atoms that carry a charge
    • Examples: SO4^(2-) (Sulfate), OH^- (Hydroxide), NH4^+ (Ammonium), C2H3O2^- (Acetate), NO3^- (Nitrate), PO4^(3-) (Phosphate), CN^- (Cyanide), MnO4^- (Permanganate), Cr2O7^(2-) (Dichromate)
    • Important to memorize for chemistry courses

Naming Compounds

  • Molecular Compounds: Use prefixes to denote the number of each element
    • Prefixes: Mono (1), Di (2), Tri (3), Tetra (4), Penta (5), Hexa (6), Hepta (7), Octa (8), Nona (9), Deca (10)
    • Examples: CO2 (Carbon dioxide), N2O5 (Dinitrogen pentoxide)
  • Ionic Compounds: Metal + Non-Metal, no prefixes
    • Use suffix 'ide' for the non-metal
    • Examples: Ki (Potassium iodide), MgBr2 (Magnesium bromide)
    • For transition metals: Use Roman numerals to denote charge; e.g. FeCl2 (Iron II Chloride), FeCl3 (Iron III Chloride)
  • Polyatomic Ionic Compounds: Recognize polyatomic ions; e.g. Na2SO4 (Sodium sulfate), KNO3 (Potassium nitrate)
    • Multiple polyatomic ions need parentheses e.g., Al2(SO4)3 (Aluminum sulfate)

Writing Formulas

  • Ionic Compounds: Balance charges
    • Examples: K3PO4 (Potassium phosphate), CaI2 (Calcium iodide)
    • Use parentheses for multiple polyatomic ions
  • Molecular Compounds: Use prefixes to write; reverse of naming
    • Examples: PCl5 (Phosphorus pentachloride), SF4 (Sulfur tetrafluoride)

Isotopes

  • Atoms of the same element with different numbers of neutrons
    • Examples: C-12, C-13
      • C-12 (6 protons, 6 neutrons), C-13 (6 protons, 7 neutrons)
    • Identify using mass number and atomic number
  • Determining Subatomic Particles
    • Protons: Equal to atomic number
    • Neutrons: Mass number - Atomic number
    • Electrons: Atomic number - charge
  • Examples: Calculation
    • N-15: 7 protons, 8 neutrons, 7 electrons
    • Al-27 (3+): 13 protons, 14 neutrons, 10 electrons
    • S-34 (2-): 16 protons, 18 neutrons, 18 electrons