Overview
This lecture introduces the structure and organization of the periodic table, the classification and naming of elements and compounds, and methods for calculating subatomic particles in atoms and ions.
Periodic Table Basics
- Group 1 (alkali metals): H, Li, Na, K, Rb, Cs; form +1 ions, except hydrogen.
- Group 2 (alkaline earth metals): Be, Mg, Ca, Sr, Ba; form +2 ions.
- Groups 13-18 include boron group, carbon group, nitrogen group, oxygen group (chalcogens), halogens, and noble gases.
- Transition metals are found in groups 3-12, inner transition metals include lanthanides and actinides.
- Metals are left of the metalloid line, non-metals are right, metalloids are on the line (e.g., Si, Ge).
Atoms, Molecules, Elements, and Compounds
- Atoms: Fundamental particles of elements (e.g., Fe, Zn).
- Molecules: Two or more atoms bonded (e.g., O₂, N₂, S₈).
- Pure element: Only one type of atom (can be atom or molecule).
- Compound: Made of two or more different types of atoms.
- Ionic compounds: Formed from metals and non-metals; composed of ions (e.g., NaCl).
- Molecular compounds: Formed from nonmetals (e.g., CO₂).
Determining Metals, Nonmetals, and Metalloids
- Use the periodic table; metals left, nonmetals right, metalloids on dividing line.
- Metalloids have properties between metals and nonmetals.
Naming Compounds
- Molecular compounds: Use prefixes (mono-, di-, tri-, etc.) and suffix "-ide" (e.g., CO₂ = carbon dioxide).
- Ionic compounds: Name metal first, then nonmetal with "-ide"; do not use prefixes (e.g., MgBr₂ = magnesium bromide).
- Polyatomic ions: Memorize common ions like sulfate (SO₄²⁻), nitrate (NO₃⁻), hydroxide (OH⁻), ammonium (NH₄⁺).
Naming Compounds with Transition Metals
- Use Roman numerals for metal charge when multiple oxidation states are possible (e.g., FeCl₂ = iron(II) chloride, FeCl₃ = iron(III) chloride).
Writing Chemical Formulas
- Molecular: Use prefixes for subscripts (e.g., phosphorus pentachloride = PCl₅).
- Ionic: Balance charges between ions; use parentheses for multiple polyatomics (e.g., aluminum sulfate = Al₂(SO₄)₃).
Isotopes and Atomic Structure
- Isotopes: Same element, different mass numbers (e.g., carbon-12 vs carbon-13).
- Protons = atomic number; Neutrons = mass number - atomic number; Electrons = protons - charge.
- Atoms are neutral (protons = electrons); ions have unequal numbers.
Key Terms & Definitions
- Valence Electrons — electrons in the outermost shell of an atom.
- Cation — positively charged ion.
- Anion — negatively charged ion.
- Isotope — atoms of same element with different neutron numbers.
- Polyatomic Ion — an ion made of multiple atoms.
- Molecular Compound — compound of nonmetals.
- Ionic Compound — compound of metal and nonmetal ions.
Action Items / Next Steps
- Print and study a periodic table.
- Memorize names and charges for common elements and polyatomic ions.
- Practice naming and writing formulas for compounds.
- Review calculation of protons, neutrons, and electrons for various atoms and ions.