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The Periodic Table of the Elements

The Periodic Table of the Elements. Ch 15 Representative and Transition Elements. Development of the Periodic Table. In 1830, 55 different elements had been isolated and named-the list is still growing. Development of the Periodic Table.

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The Periodic Table of the Elements

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  1. The Periodic Table of the Elements Ch 15 Representative and Transition Elements

  2. Development of the Periodic Table • In 1830, 55 different elements had been isolated and named-the list is still growing www.brainybetty.com

  3. Development of the Periodic Table • Dmitri Mendeleev- Russian Chemist published the first version of the Periodic Table in 1869 • Arranged the elements by their atomic mass • Recognized patterns-elements with similar properties fell into groups • Left gaps for missing elements • Made predictions for the properties of missing elements www.brainybetty.com

  4. Today’s Periodic Table www.brainybetty.com

  5. Columns of elements are called groups or families. Elements in each family have similar but not identical physical and chemical properties. For example, lithium (Li), sodium (Na), potassium (K), and other members of family IA are all soft, white, shiny metals. All elements in a family have the same number of valence electrons. Each horizontal row of elements is called a period. The elements in a period are not alike in properties. In fact, the properties change gradually and predictably across even given row. The first element in a period is always an extremely active solid. The last element in a period, is always an inactive gas. Families Periods www.brainybetty.com

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  9. Properties of Metals • good conductors of heat and electricity. • shiny. • ductile (can be stretched into thin wires). • malleable (can be pounded into thin sheets). • A chemical property of metal is its reaction with water which results in corrosion. www.brainybetty.com

  10. Properties of Non-Metals • Poor conductors of heat and electricity. • Not ductile or malleable. • Solid non-metals are brittle and break easily. • Dull • Many are gases. Sulfur www.brainybetty.com

  11. Properties of Metalloids • Metalloids (metal-like) have properties of both metals and non-metals. • Solids that can be shiny or dull. • Conduct heat and electricity better than non-metals but not as well as metals. • Ductile and malleable. Silicon www.brainybetty.com

  12. The most abundant element in the earth’s crust is oxygen. www.brainybetty.com

  13. Key to the Periodic Table • Elements are organized on the table according to their atomic number, usually found near the top of the square. • The atomic number refers to how many protons an atom of that element has. • For instance, hydrogen has 1 proton, so it’s atomic number is 1. • The atomic number is unique to that element. No two elements have the same atomic number. www.brainybetty.com

  14. What’s in a square? • Different periodic tables can include various bits of information, but usually: • atomic number • symbol • atomic mass • number of valence electrons • state of matter at room temperature. www.brainybetty.com

  15. Symbols • All elements have their own unique symbol. • It can consist of a single capital letter, or a capital letter and one or two lower case letters. C Carbon Cu Copper www.brainybetty.com

  16. Atomic Mass and Isotopes • While most atoms have the same number of protons and neutrons, some don’t. • Some atoms have more or less neutrons than protons. These are called isotopes. • An atomic mass number with a decimal is the total of the number of protons plus the average number of neutrons. www.brainybetty.com

  17. Atomic Mass Unit (AMU) • The unit of measurement for an atom is an AMU. It stands for atomic mass unit. • One AMU is equal to the mass of one proton. www.brainybetty.com

  18. Atomic Mass Unit (AMU) • There are 6 X 1023 or 600,000,000,000,000,000,000,000 amus in one gram. • (Remember that electrons are 2000 times smaller than one amu). www.brainybetty.com

  19. Groups 1 and 2 • Always found in nature combined with other elements • Active metals • Readiness to form new substances • All metals except hydrogen www.brainybetty.com

  20. Group 1-Alkali Metals • Silvery solids • Low densities • Low melting points • Increase in reactivity as you move from top to bottom • Most reactive is Francium(Fr) www.brainybetty.com

  21. What does it mean to be reactive? • We will be describing elements according to their reactivity. • Elements that are reactive bond easily with other elements to make compounds. • Some elements are only found in nature bonded with other elements. • What makes an element reactive? • An incomplete valence electron level. • All atoms (except hydrogen) want to have 8 electrons in their very outermost energy level (This is called the rule of octet.) • Atoms bond until this level is complete. Atoms with few valence electrons lose them during bonding. Atoms with 6, 7, or 8 valence electrons gain electrons during bonding. www.brainybetty.com

  22. Alkali Metals • Uses: • Lithium(Li)—batteries • Sodium(Na)—table salt • Sodium(Na) and Potassium(K)—dietary requirements www.brainybetty.com

  23. Group 2-Alkaline Earth Metals • Each is denser, harder, and has a higher melting point than the alkali metal in same period • Reactive, but not as reactive as alkali metals www.brainybetty.com

  24. Alkaline Earth Metals • Uses: • Beryllium(Be)—found in gems emerald and aquamarine • Magnesium(Mg)—found in chlorophyll of green plants www.brainybetty.com

  25. Groups 13 thru 18 • Not all solid metals • A single group can contain metals, nonmetals, and metalloids • A single group can also have members that are solids, liquids, and gases www.brainybetty.com

  26. Group 13—Boron Family • All metals except boron(B) (brittle, black metalloid) • Used to make a variety of products • Cookware—boron(B) • Soft-drink cans—aluminum(Al) • Computer chips--gallium(Ga) www.brainybetty.com

  27. Group 14—Carbon Group • Carbon(C)—nonmetal • Diamond and graphite • Found in all living things • Silicon(Si) & Germanium(Ge)—metalloid • Semiconductors • Computer chips • Tin(Sn) & Lead(Pb)-metal • Two heaviest elements in group • Lead—x-ray aprons, car batteries • Tin—pewter, toothpaste, coating for steel cans www.brainybetty.com

  28. Group 15—The Nitrogen Group • Nitrogen(N) & Phosphorus(P) • Nonmetals • Required by living things • Part of DNA • Nitrogen(N) • 80% of air you breathe • Get nitrogen for body from eating plants • Phosphorus(P) • White phosphorus—can’t be exposed to air—it will explode !! • Red phosphorus—used for head of matches • Also needed for healthy teeth and bones www.brainybetty.com

  29. Group 16—the Oxygen Family • Oxygen(O) • 20% of Earth’s atmosphere • Required for combustion • Ozone shields organisms from radiation • Sulfur(S) • Solid, yellow nonmetal • Used to make sulfuric acid • Paint, fertilizer, detergent, rubber • Selenium(Se) • Conducts electricity when exposed to light • Used in solar cells, photographic materials www.brainybetty.com

  30. Group 17—The Halogen Group • All non-metals except for astatine (radioactive metalloid) • Means “salt-former” • Example, table salt—sodium chloride • Most reactive is fluorine • Least reactive is iodine • Chlorine(Cl)kills bacteria in water www.brainybetty.com

  31. Group 18—The Noble Gases • Rarely combine with other elements • Great for signs • Each glows a different color light when electricity is passed through • Helium(He) • Less dense than air • Great for balloons • Argon(Ar) • Most abundant • Krypton(Kr) • Used to illuminate landing strips • Radon(Rn) • Radioactive; produced naturally • Harmful; can cause lung cancer www.brainybetty.com

  32. Transition Elements • Groups 3-12 • All metals • Most found combined with other elements in ores • Few found as pure elements gold(Au) and silver(Ag) www.brainybetty.com

  33. Iron Triad • Elements in period 4 • Iron, cobalt, nickel • Have magnetic properties • Industrial magnets—alloy of nickel, cobalt, aluminum • Nickel used in batteries • Iron is necessary in hemoglobin to transport oxygen in body • Iron also combined with other metals to produce steel www.brainybetty.com

  34. Uses of Transition Elements • Tungsten(W)—highest melting point of any metal • Used as filament in light bulbs • Mercury(Hg)—lowest melting point • Used in thermometers and barometers • Only metal liquid at room temperature • Poisonous to living things www.brainybetty.com

  35. Uses of Transition Elements • Chromium(Cr)—comes from Greek word for color, chroma • Used in paints • Platinum(Pt) group • Ruthenium, rhodium, palladium, osmium, iridium, and platinum • Can be used as catalysts • Used to produce electronics www.brainybetty.com

  36. Inner Transition Metals • Lanthanide Series • Actinide Series www.brainybetty.com

  37. Lanthanides #58-71 • Also called rare earth elements • Usually found in combination with oxygen in Earth’s crust • Soft metals that can be cut with a knife www.brainybetty.com

  38. Actinides # 90-103 • All radioactive • Thorium(Th), protactinium(Pa), uranium(U) are only ones found naturally on Earth • Plutonium(Pu)—used to fuel nuclear power plants • Americium(Am)—used in smoke detectors • Californium-252(Cf)—used to kill cancer cells • Synthetic-Not occur in nature www.brainybetty.com

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