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FAMILIES OF ELEMENTS

FAMILIES OF ELEMENTS. HOW ARE ELEMENTS CLASSIFIED?. By similar physical & chemical properties. ALKALI METALS. group 1 shiny malleable ductile React violently w/ water Very reactive b/c it has only one valence electron Has +1 charge Not found in nature as elements

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FAMILIES OF ELEMENTS

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  1. FAMILIES OF ELEMENTS

  2. HOW ARE ELEMENTS CLASSIFIED? • By similar physical & chemical properties.

  3. ALKALI METALS • group 1 • shiny • malleable • ductile • React violently w/ water • Very reactive b/c it has only one valence electron • Has +1 charge • Not found in nature as elements • Found only in compounds • Ex: salt (NaCl) Lithium • used to treat bipolar disorder

  4. ALKALI EARTH METALS • Group 2 • two valence electrons • +2 charge • shiny • malleable • ductile • Form compounds in stone & human body Calcium (Ca): • Shells of sea animals, coral reefs (limestone), skeletal structure humans … Magnesium (Mg) • Air plane construction • Activates enzymes that speed up processes in humans • brilliant white color in fireworks Medicines • milk of magnesia • Epsom salt

  5. TRANSITION METALS • groups 3-12 • most familiar • found in elemental state Iron • most abundant metal • used in steel Aluminum • making containers, automotive parts, cookware… MERCURY • only metal at room temperature • used in thermostats, thermometers, batteries …

  6. NONMETALS • Some elements found in groups 13-16 & all elements in groups 17-18 • except hydrogen • usually gases or brittle solids at room temperature • poor conductor of heat & electricity • may be solids, liquids, or gases at room temperature.

  7. HALOGENS • Group 17 • very reactive in elemental state Chlorine • greenish yellow gas • Kills bacteria • Elemental chlorine is very poisonous • obtained from seawater Fluorine • Poisonous yellow gas • used in toothpaste Bromine • Dark red liquid • only nonmetal liquid at room temperature • obtained from seawater Iodine • shiny, purple-gray solid • Used as disinfectant • obtained from seawater

  8. NOBLE GASES • group 18 • Exist only as single atoms instead of molecules • Unreactive b/c orbitals are full of electrons Neon • Signs Helium • Less dense than air • Gives lift to blimps & balloons Argon/Krypton • Used in light bulbs

  9. SEMICONDUCTORS • elements that can conduct electricity under certain conditions • Aka metalloids: • Composed of only six elements • Boron, silicon, germanium, arsenic, antimony & tellurium Boron • Extremely hard • Added to steel to increase hardness & strength at high temperatures. Antimony • Used as fire retardants Silicon • Makes up 28% of earths crust • Sand most common compound • Used in electronics

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