C8: The periodic table

  1. Arrangement of elements

  • Groups and periods

    • elements are arranged in order of increasing atomic number

    • Groups: vertical columns

    • Periods: Horizontal rows

  • Metals and non-metals

    • Non-metals: top right

    • Metals: top left

    • Transition metalloids: middle

  • Group trends

    • Metals: more reactive going down

    • Non-metals: less reactive going down

    • Density and m.p increasing down the group

    • Atoms getting larger = more metallic

  1. Group 1 properties: Alkali metals

  • Highly reactive (reactivity increase going down) → stored in oil

  • Have a light grey, silvery surface when cut but tarnishes and dulls

  • Melting/boiling points decrease down the group

  • Metals get softer down the group

  • Densities increase down the group

  1. Group 7 properties

  • Most reactive non-metals

  • Exist as diatomic molecules

  • Going down:

    • Reactivity decreases

    • B.p, density decreases

    • gas → solid

    • pale → dark

  1. Transition elements

  • Features:

    • Hard and strong

    • High density

    • High m.p/b.p

  • Distinctive properties:

    • Colored compounds

    • Catalysts

  1. Noble gases

  • Most stable

  • Properties

    • Stable electronic configurations

    • Do not readily react with other atoms → exist as single atoms