CHE2C - Main Group

Group 1 - Alkali Metals

• Common OS = +1

• Highly Reactive

• Reactions with water

  • Metal oxide, H₂

• Reactions with Oxygen

  • Li → Li₂O

  • Na → Na₂O₂

  • K/Rb/Cs —> MO₂

Hydrogen

• Lightest element

• Low IMFS

• Non-metal

• Location on table is debated

  • Could be placed w/ Halogens → same distance from filled shell

  • Could be placed with Carbon → half-filled valance

Group 2 - Alkaline Earth Metals

• Common OS = +2

• Low: density melting/boiling points

• All form basic oxides with oxygen

• Be

  • forms more covalent bonds

  • less reactive, smaller, harder

  • higher melting point

  • higher IE

• Mg/Ca

  • Biological importance

  • Hard water

• Ba

  • Toxic, absorbs X-rays

  • Used for imaging in gastromedicine

• Ra = radioactive

Group 13

• Common OS = +1, +3

• Metals = soft/reactive

• B

  • nonmetal

  • Supports 6 valance electrons max (exception: BH₃)

• Al

  • oxides used to make precious gems

  • determine color when added to transition metals

• Ga

  • Higher density liquid, lower melting point

Group 14

• Common OS = +4, +2 (-4 for nonmetals)

• C

  • 4 bonds

  • pi bonds

  • basis for life

  • Allotropes: Diamond, graphite, fullerenes

• Si

  • Si-O bonds stronger than Si-Si

  • Geology

• Ge

  • rare, semiconductors

• Sn

  • Soft metal, silvery color

  • Allotropes: White, Grey, Brittle

• Pb

  • Soft, Toxic

  • Low melting point

Group 15

• Many OS

• N

  • Can be stable or highly reactive (N₂ vs TNT)

  • forms pi bonds

  • important for DNA, N fixation, atmosphere

• P

  • Larger

  • D-orbitals for electrons and bonding

  • ATP ADP

  • fertilizer

• As

  • Toxic semi-metal

• Bi

  • Heavy, slightly toxic

  • Substitute for lead

Group 16

• Commos OS: -2, -1 (peroxides)

• O

  • O₂ or O₃ (allotropes)

  • O₃ = toxic, important for atmosphere, water treatment

• S

  • Stinky

  • 30+ solid allotropes

  • S₈ = ring structure

• Po

  • Radioactive

  • Lethal, found in tobacco

Group 17 - Halogens

• Common OS: -1

• F

  • Most electronegative element

  • Small

  • Dental care, “forever chemicals”

• At

  • Radioactive

  • Longest lived isotope lasted 8.3 h

Group 18 - Noble Gases

• Common OS: 0

• He

  • Lightest noble gas

  • No compounds

• Ne

  • Used in neon lights

  • No compounds

• Ar

  • Major component of air

  • Forms some compounds

• Kr/Xe

  • Expanded octet → many stable compounds

• Rn

  • Radioactive, many compounds