The Elements Chapter 7

Properties of s-Block Elements Representative Elements ▫The lower the ionization energy, the more reactive the metal  Metal groups – reactivity increases as the atomic number increases ▫The higher the ionization energy, the more reactive the nonmetal  Nonmetal groups – reactivity decreases as the atomic number increases

Hydrogen ▫Placed in group 1A only b/c it has 1 valence electron ▫Has metallic and nonmetallic properties, so is not considered part of any group Group 1A: Alkali Metals ▫Lose 1 valence electron and form a 1+ ion ▫Soft ▫Lithium  Least reactive alkali metal  Long-lasting batteries  Drug to treat bipolar disorders ▫Sodium and potassium  Fireworks  Fertilizers

Group 2A: Alkaline Earth Metals ▫Form compounds with oxygen (oxides) ▫Shiny solids that are harder than alkali metals ▫Lose 2 valence electrons to form 2+ ions ▫Calcium  Healthy bones and teeth  Calcium carbonate  Main ingredient in limestone, chalk, and marble  Antacid tablets  Abrasives, such as toothpaste ▫Magnesium – alloys of Mg w/ Al and Zn are strong as steel but lighter ▫Barium – used in paints, glass; used as diagnostic tool for internal medicine

Properties of p-Block Elements Group 3A: The Boron Group ▫Boron  Borosilicate glass for cookware  Borax - cleanser  Boric acid – disinfectant ▫Aluminum – most abundant metal  Aluminum sulfate in anti-perspirants ▫Gallium  Thermometers  Blue lasers

Group 4A: The Carbon Group ▫Carbon  Organic chemistry studies C-containing compounds  Inorganic chemistry studies all others  Mineral – inorganic element found in crystals  Ore – material from which minerals can be removed  Diamond and graphite are allotropes of C  Allotropes – forms of an element in the same physical state that have different structures and properties ▫Silicon  Semi-conductors  Sand and glass

Group 5A: The Nitrogen Group ▫Nitrogen – 78% of earth’s atmosphere  Ammonia  TNT, nitroglycerine ▫Phosphorus  Matchbox striking surface  Fertilizers  Fertilizers containing phosphates harm environment ▫Arsenic – toxin used in poisons ▫Bismuth – main ingredient in Pepto Bismol

Group 6A: The Oxygen Group ▫Oxygen – most abundant element in earth’s crust  Bonds with most elements ▫Sulfur  SO 2 – reacts w/water vapor to form acid rain ▫Selenium  Vitamins  Solar panels  Photocopiers

Group 7A: The Halogens ▫Form compounds w/ almost all metals (salts) ▫Fluorine – most electronegative element, so greatest tendency to attract electrons  Toothpaste  Drinking water ▫Chlorine  Disinfectant  Bleach  HCl in stomach used to digest food  PVC ▫Iodine  Maintains healthy thyroid gland  Kills bacteria

Properties of d-Block and f-Block Elements Transition Metals ▫Silver is best conductor ▫Iron and titanium are used as structural materials b/c of their strength ▫Chromium is hardest  6 unpaired electrons ▫Magnetism – ability of a substance to be affected by a magnetic field  Moving electron creates magnetic field; b/c paired electrons move in opposite directions, their magnetic fields tend to cancel ▫Sources of transition metals  U.S. imports more than 60 materials that are classified as “strategic and critical”

Inner Transition Metals ▫Lanthanide series – silvery metals w/ relatively high melting points ▫Actinide series  Radioactive  Transuranium element – atomic number >92  Plutonium is used as fuel in nuclear power plants  Americium – used in smoke detectors