Overview
This lecture covers the 11 families of the periodic table, describing their main properties and examples for each group.
Periodic Table Families
- Elements are grouped into families based on similar chemical behavior and properties.
- The 11 families are: alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, halogens, lanthanides, actinides, non-metals, noble gases, and unknown properties.
Alkali Metals
- Alkali metals are shiny, soft, and highly reactive at standard temperature and pressure.
- They have one outermost electron in an S orbital, leading to similar properties.
- Alkali metals are good conductors, have luster, ductility, and malleability.
Alkaline Earth Metals
- Alkaline earth metals are shiny, silvery-white, and somewhat reactive.
- They have two outer electrons in an S orbital.
- These are good electrical conductors.
Transition Metals
- Transition metals contain 38 elements, the largest family.
- They have typical metal properties: silvery, malleable, ductile, and conduct heat/electricity.
- Transition metals have electrons in a D orbital and form positive ions.
Post-Transition Metals
- Post-transition metals are close to non-metals and are also called poor metals or P block metals.
- They are soft, brittle, have low strength, and low melting and boiling points.
Metalloids
- Metalloids have properties intermediate between metals and non-metals.
- They appear metallic, are brittle, and are moderate conductors.
- No strict definition or full agreement on which elements are metalloids.
Halogens
- Halogens mean "salt formers" due to their ability to form salts with metals.
- Highly reactive as they need one electron to fill their outer shell.
- Get darker down the group; reactivity driven by electron shell completion.
Lanthanides
- Also called rare earth elements, used in metal alloys for strength/hardness.
- Silvery-white, relatively soft, and include 14–15 elements.
Actinides
- Used in nuclear energy and defense (e.g., uranium, plutonium).
- All are radioactive, malleable, ductile, and silvery, and solid at room temperature.
Non-Metals
- Non-metals lack metallic properties, ranging from gases to solids.
- Poor conductors due to limited electron movement.
- Hydrogen is a non-metal and accounts for much of the universe's matter.
Noble Gases
- Noble gases are colorless, odorless, and monatomic under standard conditions.
- Not reactive due to full outer electron shells.
- Each noble gas emits a different color when electrified (except radon).
Elements with Unknown Properties
- Elements with unknown properties are poorly documented due to short half-lives and few atoms available.
- Their group affiliations are unclear.
Key Terms & Definitions
- Family — A group of elements in the periodic table with similar properties.
- S orbital — Region where an electron orbits in a spherical path.
- D orbital — Region in atoms where electrons move, characteristic of transition metals.
- Metalloids — Elements with properties between those of metals and non-metals.
- Anion — Atom or molecule with a non-neutral (negative or positive) electric charge.
- Monatomic — Consisting of single atoms, not molecules.
Action Items / Next Steps
- Review the 11 periodic table families and their characteristic properties.
- Learn the examples and distinctions among families for exams.