Transition elements

Metals in the Middle

  • Groups 3 – 12 = transition elements
  • All metals
  • Change less noticeably across period than representative elements

Iron triad (p448)

  • Period 4 – iron, cobalt, nickel
  • Such similar properties = iron triad
  • Are magnetic
  • Industrial magnets = alloy of nickel, cobalt, aluminum
  • Nickel = used in batteries
  • Iron
  • necessary part of hemoglobin
  • mixed with other metals and carbon to create steel = used in buildings as structures (give strength)

Uses of Transition Elements (p449)

  • Have higher melting points than representative elements
  • Tungsten = used in lightbulbs b/c has highest melting point of any element and doesn’t melt when electric passed thru it.
  • Mercury =
  • lowest melting point = used in thermometers/barometers
  • only metal that is a liquid at room temp.
  • poisonous to humans
  • chromium
  • name from greek word for color, used in paints
  • many transition elements combine with other substances to form brilliant colors
  • ruthenium, rhodium, palladium, osmium, iridium, platinum =
  • platinum group b/c similar properties
  • do not combine easily with other elements = can be used as catalysts
  • nickel, zinc, cobalt can also be used as catalysts
  • catalysts are used to produce electronic and consumer goods, plastics, medicines

Inner Transition Elements (p450)

Lanthanides

  • rare earth (b/c at one time thought to be rare)
  • actually found combined with Oxygen in earth’s crust
  • soft metals – can be cut with knife
  • hard to separate b/c so similar and occur in same ore
  • not rare – cerium occurs more often than lead in earth’s crust
  • Cerium – used in misch metal to make flint (also includes lanthanum, neodymium and iron)

Actinides

  • bottom period
  • all are radioactive – unstable, decay to form other elements
  • Thorium, protactinium, uranium – only actinides found naturally on earth
  • All other actinides are synthetic
  • Plutonium = fuel in nuclear power plants
  • Americium – used in smoke detectors
  • Californium - used to kill cancer

Dentistry and Dental Material (p452)

  • Amalgam = used to fill cavities for 150 years
  • Amalgam = mixture of silver, copper, tin, mercury
  • Ppl are concerned about mercury vapor so now dentist use resins
  • Orthodontists – use nickel and titanium alloys for brace wires
  • Wires heated to lock in shapes
  • If they try to get out of shape, the will try to return to original shape

P451 – Visualizing Synthetic Elements

-Particle accelerator – used to make synthetic elements with atomic number greater than uranium

-Atomic nuclei are collided at high speeds to fuse nuclei together = new heavier isotopes

-May survive for only a moment until breaking apart