Periodic Table

🧭 Metals, Nonmetals, Metalloids

Staircase: separates metals (left) from nonmetals (right); metalloids along the line.
Metals: shiny, malleable, ductile, conduct heat/electricity, lose electrons (cations).
Nonmetals: dull, brittle, poor conductors, gain electrons (anions).
Metalloids: have properties of both; semiconductors (ex: Si, B, As).
Classify: use properties to decide — shiny & conductive = metal; dull & brittle = nonmetal; in-between = metalloid.

🧬 Periodic Table Setup

Families (Groups): columns → same # valence electrons, similar properties.

  • Group 1 = Alkali metals (very reactive)

  • Group 2 = Alkaline earth metals (reactive)

  • Groups 3–12 = Transition metals (hard, shiny, good conductors)

  • Group 17 = Halogens (very reactive nonmetals)

  • Group 18 = Noble gases (unreactive, full shell)

Periods: rows → same # of energy levels.
Difference: family = vertical column; period = horizontal row.

⚡ Periodic Trends

Atomic Radius

  • = distance from nucleus to outermost electron

  • Increases ↓ a group, decreases → across a period

  • Largest atoms = bottom left (Fr)

Ionization Energy

  • = energy to remove an electron

  • Increases → across, decreases ↓

  • Highest = top right (He, F)

Electronegativity

  • = ability to attract electrons in a bond

  • Increases → across, decreases ↓

  • Most electronegative = F (fluorine)