Overview
This lecture covers the organization of the periodic table, key element groups, and their chemical properties, including valence electrons, charges, and physical states.
Periodic Table Organization
- Group 1A (alkali metals): highly reactive metals with 1 valence electron, form +1 cations.
- Group 2A (alkaline earth metals): reactive metals with 2 valence electrons, form +2 cations.
- Transition metals: central block, variable reactivity and charges, includes Fe (iron), Cu (copper), Zn (zinc), Ag (silver), Au (gold), etc.
- Group 7A/17 (halogens): nonmetals with 7 valence electrons, form -1 anions, highly reactive.
- Group 8A/18 (noble gases): inert gases with full valence shells, very stable, e.g., He, Ne, Ar.
- Group 6A/16 (chalcogens): 6 valence electrons, form -2 anions, includes O, S, Se.
- Group 5A/15: 5 valence electrons, typically form -3 anions (e.g., N, P).
- Group 3A/13: 3 valence electrons, form +3 cations (e.g., B, Al).
- Group 4A/14: 4 valence electrons, charge varies (+2 or +4), e.g., C, Si, Sn, Pb.
- Inner transition metals: lanthanides and actinides.
Metals, Nonmetals & Metalloids
- Metals: left and middle of the table, conduct heat/electricity, malleable, ductile, electropositive.
- Nonmetals: upper right, insulators, gain electrons (electronegative).
- Metalloids: along stair-step line, intermediate properties, semiconductors (e.g., Si, Ge).
- Francium: most electropositive metal; Fluorine: most electronegative nonmetal.
Atomic Structure & Notation
- Atomic number = number of protons.
- Mass number = protons + neutrons.
- Number of neutrons = mass number - atomic number.
- Number of electrons = atomic number - charge (neutral atom: electrons = protons).
- In ions: electrons differ from protons based on charge.
- Most atom mass is in the nucleus (protons and neutrons).
- Electrons orbit the nucleus.
Element Symbols & Naming
- Know the symbols and names for common elements (e.g., H = hydrogen, Na = sodium, Fe = iron, etc.).
- Diatomic elements: H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂.
Physical States at Room Temperature
- Most metals: solid (except Hg, liquid).
- Bromine: red liquid; Iodine: purple solid.
- Gases: H₂, N₂, O₂, F₂, Cl₂, noble gases.
Typical Quiz/Exam Questions
- Classify elements as metals, nonmetals, or metalloids.
- Identify group properties and typical ion charges.
- Determine number of protons, neutrons, electrons from atomic/mass number.
- Recognize physical states of elements at room temperature.
Key Terms & Definitions
- Valence electron — Electron in the outermost shell, involved in bonding.
- Cation — Positively charged ion.
- Anion — Negatively charged ion.
- Atomic number — Number of protons in an atom.
- Atomic mass — Weighted average mass of protons and neutrons.
- Diatomic molecule — Molecule with two atoms of the same element.
- Metalloids — Elements with properties between metals and nonmetals.
Action Items / Next Steps
- Memorize common element names and symbols.
- Practice determining protons, neutrons, and electrons from atomic data.
- Review group properties and ion charges.
- Learn the seven diatomic elements.