metals - make up 3/4 of the periodic table, in left/middle part
- shiny luster
- malleable (can be pounded into thin sheets)/ductile (can be drawn into wires)
- good conductors of heat/electricity
- tend to form cations (have low ionization energies) in aqueous solutions
- compounds of metals w/ nonmetals tend to be ionic
- most metal oxides are basic (form hydroxides when dissolved in water)
- metal oxides w/ acid form salt
- alkali metals (group 1A) - soft metallic solids
- have the lowest I1 on each row
- hydride ion - H-; bonds w/ alkali metals to form hydrides
- reacts exothermically w/ water
- superoxide - O2-; combines w/ potassium, rubidium, cesium
- emit certain colors when heated by a flame
- alkaline earth metals (group 2A) - denser/harder than alkali metals
- less reactive than alkali metals
- Mg used for lightweight structure alloys because layer of MgO protects it from other chemicals
nonmetals - on right side of periodic table
- no luster, has various appearances
- poor conductors of heat/electricity
- most nonmetal oxides are acids
- tend to form anions/oxyanions in aqueous solutions
- molecular substances - compounds made up only of nonmetals
- hydrogen - doesn't really belong in a particular group
- exists as H2 gas in most conditions
- can be metallic at very high pressures
- has much higher I1 than other alkali metals (lacks any type of nuclear shielding)
- oxygen group (group 6A)
- elements change from nonmetal to metal as you go down the group
- allotrope - different form of same element in same state
- ozone - O3, less stable than O2
- sulfur - exists naturally as S8 rings
- halogens (group 7A) - aka "salt formers"
- melting/boiling points increase as atomic number increases
- very highly negative electron affinities
- Cl - most industrially useful halogen
- forms halide compounds w/ hydrogen
- noble gases (group 8A) - monoatomic nonmetals, gas at room temperature
- have completely filled s and p subshells
- very unreactive
metalloids - have properties intermediate between metals/nonmetals
- have only some metallic properties, but lack others
- many used as electrical semiconductors, integrated circuits