Overview
This lecture explains the structure and organization of the periodic table, highlighting its groups, periods, element families, and the properties distinguishing metals, nonmetals, and metalloids.
Structure of the Periodic Table
- The periodic table arranges elements into rows (periods/series) and columns (groups/families) based on repeating properties.
- Early periodic tables arranged elements by atomic mass, but this caused confusion due to similar masses.
- The modern periodic table is organized by increasing atomic number.
Periodic Law and Organization
- Periodic law states that arranging elements by increasing atomic number produces periodic repetition of physical and chemical properties.
- A section of elements (inner transition metals) is placed below the main table for compactness.
- Metals are found on the left of the staircase, non-metals on the right, and metalloids along the staircase.
Properties of Metals, Nonmetals, and Metalloids
- Metals: good conductors, high luster, mostly solid at room temp (except mercury), ductile, and malleable.
- Non-metals: poor conductors (except carbon), brittle, usually found as gases or brittle solids.
- Metalloids: share properties of both metals and non-metals; example: silicon is a poor conductor and can be made into thin sheets.
Important Element Families
- Group 1: Alkali metals—explosive in water, form cations.
- Group 2: Alkaline earth metals—form cations as well.
- Group 17: Halogens—form anions.
- Group 18: Noble gases (inert gases)—rarely react with other elements unless under extreme conditions.
Regions of the Periodic Table
- Representative elements: commonly used elements, found on the sides of the table.
- Transition metals: block in the middle of the table.
- Inner transition metals: usually displayed below the transition metals.
Key Terms & Definitions
- Period — a horizontal row on the periodic table.
- Group/Family — a vertical column on the periodic table.
- Periodic Law — the principle that elemental properties recur periodically when arranged by atomic number.
- Metal — an element with high conductivity, luster, and malleability.
- Nonmetal — an element that is brittle and a poor conductor of heat/electricity.
- Metalloid — an element with properties between metals and nonmetals.
- Cation — a positively charged ion.
- Anion — a negatively charged ion.
Action Items / Next Steps
- Review the layout and key groups of the periodic table.
- Memorize the properties of metals, nonmetals, and metalloids.
- Study the location and characteristics of alkali metals, alkaline earth metals, halogens, and noble gases.